TREATMENT OF STAGE II POSTERIOR TIBIAL TENDON RUPTURE WITH FLEXOR DIGITORUM LONGUS TENDON TRANSFER AND CALCANEAL OSTEOTOMY
January 1st, 2003
Mark S. Myerson, MD; Athanasios Badekas, MD; and Lew Schon, MD
ABSTRACT
Background. To assess the efficacy of surgical correction of stage II tibial tendon rupture with medial translational calcaneus osteotomy and flexor digitorum longus tendon transfer to the navicular, we retrospectively reviewed our results of treatment of stage II posterior tibial tendon rupture in 129 patients for whom surgery was performed between 1990 and 1997.
Methods. The 129 patients (117 female, twelve male) with an average age of fifty-three years (range, thirty-four to seventy-five years) had been symptomatic for an average of 2.8 years (range, 0.5 to 7.0 years). The indication for surgery was the presence of foot pain that was refractory to shoe modifications, orthoses, and brace support. All patients had a painful flexible flatfoot without a fixed forefoot supination deformity (stage II). The surgery performed included a medial translational osteotomy of the calcaneus and transfer of the flexor digitorum longus tendon into the navicular. Additional surgeries were performed in forty-nine patients. The 129 patients were examined, radiographs were obtained, and isokinetic evaluation of both feet and lower limbs were performed at a mean of 5.2 years after surgery (range, 3.0 to 8.0 years). The AOFAS hindfoot scale was used to evaluate each patient, but because this was not a prospective study, and due to the time elapsed from the initiation of treatment, preoperative AOFAS scores were not retrospectively determined.
Results. The mean AOFAS score at the time of the follow-up examination was 79 points (range, 54 to 93). There were seven significant complications in six patients, including progressive hindfoot valgus deformity in one patient who was treated with a triple arthrodesis, overcorrection of the hindfoot in two patients necessitating revision with a lateral closing wedge calcaneus osteotomy, symptomatic sural neuritis in three patients, and weakness of the gastrocnemius resulting from overlengthening of the Achilles tendon in one patient. Isokinetic inversion and plantar flexion power and strength was compared with the contralateral limb for 121 patients and was noted to be symmetric in ninety-five, mildly weak in eighteen, and moderately weak in eight patients. Of the 129 patients, motion of the subtalar joint was normal in 56 (44 percent), slightly decreased in 66 (51 percent), and moderately decreased in 7 patients (5 percent). Anteroposterior and lateral radiographs were evaluated for the talonavicular coverage angle, talus first metatarsal angle, talocalcaneal angle, and the height of the medial cuneiform to the floor. For four of these five parameters evaluated, the correction obtained was statistically significant (p < 0.05). Of the 129 patients, 118 were entirely satisfied, seven were partially satisfied, and four were dissatisfied with the outcome of the procedure. Of the patients, 125 (97 percent) experienced pain relief, 121 (94 percent) showed improvement of function, 112 (87 percent) experienced improvement in the arch of the foot, and 108 (84 percent) were able to wear shoes comfortably without resorting to shoe modifications or orthotic arch support.
Conclusions. The surgical correction of stage II posterior tibial tendon rupture with medial translational calcaneus osteotomy and flexor digitorum longus tendon transfer to the navicular yielded excellent results with minimal complications and a high patient satisfaction rate.
INTRODUCTION
In the adult, loss of function of the posterior tibial tendon results in a progressive collapse of the medial longitudinal arch of the foot and therefore causes adult acquired flatfoot deformity. The principal function of the posterior tibial muscle is to invert the subtalar joint, which helps to stiffen or stabilize the transverse tarsal joint during heel rise. When the posterior tibial tendon ruptures, the transverse tarsal joint is not stable during heel rise, leading to prolonged calcaneal eversion and forefoot pronation. Tension on the medial-plantar side of the transverse tarsal joint is transferred to additional soft tissue supports, including the talonavicular capsule and spring ligament, and a flatfoot deformity occurs. This is followed by progressive valgus deformity of the calcaneus, plantarflexion of the talus, abduction of the fore part of the foot, and pronation deformity of the foot.
Staging of rupture of the posterior tibial tendon has been classified according to Johnson and Strom[20] and modified by Myerson[31]. The treatment of posterior tibial tendon tenosynovitis or stage I is generally nonsurgical. If conservative treatment measures fail, then tenosynovectomy is recommended, particularly for patients with a seronegative spondylarthropathy[30]. In stage II, the posterior tibial tendon is torn, the midfoot pronates, the forefoot abducts at the transverse tarsal joint, and there is valgus angulation of the heel. In this stage, however, the subtalar joint remains flexible, and arthrodesis of the hindfoot can be avoided. Various surgical treatment options are available for correction of stage II deformity, including tenodesis of the posterior tibial tendon to the flexor digitorum longus[17,29,43], flexor digitorum longus transfer to the navicular[26], subtalar arthrodesis[10,18,21], and flexor hallucis transfer to the navicular[8,38]. We and others had noted that although patients reported pain relief and improved function following correction of stage II rupture with a tendon transfer, the foot remained deformed and the results of treatment deteriorated with time[4,5,17,19,24,26]. The failure of tendon transfer or tenodesis alone may be due to persistent muscle imbalance of the hindfoot, since the Achilles tendon remains lateral to the axis of the subtalar joint and continues to be a valgus deforming force on the hindfoot[2,34]. Medial translation osteotomy of the calcaneus shifts the Achilles tendon medial to the axis of the subtalar joint, providing added support to the tendon transfer medially[27,31,35] [7,23].
We have previously reported on the short-term outcome and radiographic appearance of the foot following flexor digitorum longus tendon transfer combined with medial translational calcaneal osteotomy[32,33]. In this study we present our longer term results of treatment of stage II posterior tibial tendon rupture with flexor digitorum longus tendon transfer combined with medial translational calcaneal osteotomy after failed nonsurgical methods of treatment.
MATERIAL AND METHODS
Patient Population
Over an eight-year period (1990 to 1997), we treated 412 patients with posterior tibial tendon rupture. This group included patients with all four stages of posterior tibial tendon rupture[31], of whom 163 had a stage II deformity. Of these 163 patients, nonsurgical treatment was initiated for 148 patients and surgery was performed more promptly for fifteen patients who had already received sufficient nonsurgical care. Of the 148 patients, twenty-nine improved with nonsurgical treatment, leaving 134 patients who formed the basis for this retrospective review (fifteen patients were initially treated with surgery and 119 with subsequent surgery). Although we treated patients with rheumatoid arthritis who had deformities suggestive of posterior tibial tendon rupture, they were excluded from this study because of the variable presentation of associated foot pathology.
Nonsurgical Treatments
A total of fifty-two patients had received various combinations of nonsurgical treatments before referral, including a 6-mm medial heel and sole wedge (twenty-five patients), a rigid orthotic arch support (twenty-nine patients), a firm accommodative orthotic arch support (ten patients), a hinged polypropylene AFO ankle foot orthosis (sixteen patients), and a stirrup brace (twenty patients). Before referral to our institution, these patients had received conservative treatment for a mean duration of seven months (range, two to twenty-three months). For fifteen of these patients, the nonsurgical treatment was felt to have been adequate, no further nonsurgical treatment was provided, and surgery was recommended.
We recommended nonsurgical treatments for a total of 119 patients, including thirty seven of those who had received some prior treatment as noted above. We recommended activity modification for each patient, in addition to shoe wear and orthotic treatments. Nonsteroidal antiinflammatory medication was prescribed for forty-eight patients with tenosynovitis (swelling, warmth, and edema around the tendon) who could tolerate this medication. Patients modified their activities by limiting the number of hours that they were standing and ambulatory and by curtailing any athletic activities. We recommended an orthotic or brace support for all ambulatory activities, but no casts were used. Physical therapy was prescribed for twenty-three patients and focused on plantar flexion and inversion strengthening exercises and modalities (ultrasound and electrical stimulation) to attempt to decrease the inflammation. We did not use oral or locally injected corticosteroids, although eighteen patients had received prior treatment with corticosteroid injection, including seven patients with two or more injections. The mean duration of the conservative treatments that we initiated for 119 patients was 4.5 months (range, 1.0 to 13.0 months).
The nonsurgical treatments resulted in some improvement for ninety-five of the 119 patients, although symptoms persisted to some extent for all 119 patients. Nine patients treated with an AFO were markedly improved; however, symptoms returned immediately once the brace was discontinued, and each of these patients preferred the option of surgery to continued brace immobilization. In addition to the fifteen patients for whom surgery was performed more promptly, the remaining 119 patients did not improve sufficiently with nonsurgical treatments, and reconstruction was performed with flexor digitorum longus tendon transfer combined with medial translational calcaneal osteotomy.
Of these 134 patients who were treated with surgery, we obtained adequate follow-up for 129 patients. One patient was deceased, two were unwilling to participate in this study, and we were unable to contact the remaining two patients. These 129 patients (117 female, twelve male) with an average age of fifty-three years (range, thirty-four to seventy-five years) had been symptomatic for an average of 2.8 years (range, 0.5 to 7.0 years) before surgery. The duration of symptoms in these patients was similar to the duration of symptoms in the fifteen patients treated promptly with surgery and differed from results with patients who were treated with further nonsurgical treatments. Thirty-seven patients were under fifty years of age, sixty-three were between fifty and sixty years old, twenty-three were aged sixty to seventy, and six patients were older than seventy years of age. The average body weight at the time of the surgery was 183 pounds (range, 105 to 246 pounds). The average height at the time of the last clinical study examination was five feet four inches, and the average body mass index height/weight was 64/183 = 0.350.
For 117 of the 129 patients, the etiology of the tendon rupture was considered to be nonspecific idiopathic primary degenerative tendinosis. Ten patients had a seronegative inflammatory disease, one had Marfan syndrome, and one had Ehlers-Danlos syndrome. The mean age of these twelve patients was forty-one (range, thirty-four to fifty-one) and ten of twelve were women, while the mean age of the patients with degenerative tendinosis was fifty-five (range, thirty-nine to seventy-five).
Patients were considered suitable candidates for surgery if they met the following five criteria: 1) persistent pain and tenderness along the posterior tibial tendon refractory to shoe modifications, foot orthoses, and AFO support; 2) weakness of the posterior tibial tendon as demonstrated by inability to perform a single heel rise on the affected side; 3) at the least a grade IV/V weakness noted by manual inversion resistance testing; 4) pronation and abduction at the transverse tarsal joint and valgus angulation of the heel; and 5) a flexible subtalar joint with less than 15 degrees of fixed forefoot varus deformity. Testing for weakness in manual inversion resistance was performed by asking patients to hold their foot in plantar flexion and then having them invert in the plantar flexed position against the examiner’s hand, which was held medially by the distal end of the first metatarsal. Clinically forefoot varus was identified by holding the subtalar joint reduced with the calcaneus held in a neutral position of varus/valgus, placing the ankle in neutral dorsiflexion/plantar flexion, and measuring the plane established by the metatarsal heads relative to the axis of the medial border of the tibia. Before the operation, the patients were examined for Achilles tendon contracture with the subtalar joint in a neutral position and with the knee first in extension and then in flexion. We noted any additional foot and ankle pathology.
Operative Procedure
The patient is placed in the lateral decubitus position on a beanbag. The incision begins superior to the calcaneus and posterior to the peroneal tendons and sural nerve. The incision curves gently in a distal and inferior direction, ending at the plantar edge of the calcaneus. The lateral aspect of the calcaneus is exposed, and an oblique calcaneal osteotomy is performed with an oscillating saw blade in line with the skin incision. Care is taken to remain at least 1 cm posterior to the posterior process of the talus to avoid injury to the posterior articular surface of the subtalar joint.
The osteotomy is at a right angle to the lateral border of the calcaneus and is inclined posteriorly approximately 45 degrees to the plantar surface of the hindfoot. No wedge is removed from the calcaneus, and no attempt is made to tilt the tuberosity into varus. A toothless lamina spreader is placed in the osteotomy site, and the medial soft tissue attachments to the calcaneus are released with tension placed on the lamina spreader. The lamina spreader is withdrawn, and the posterior calcaneal tuberosity is then translated medially by a minimum of
10 mm as measured by a ruler and fixed with one 6.5-mm or 7.3-mm cancellous lag screw. Care is taken to prevent the posterior tuberosity from sliding proximally. The screw is inserted from posterior, medial, and inferior to anterior, lateral, and superior. An intraoperative fluoroscopic lateral image of the foot is obtained to confirm position of the screw. The prominent ledge of bone on the supero-lateral calcaneus is then removed with an osteotome or compacted into a smooth contour using a bone tamp and mallet. The lateral incision is then closed, the beanbag is deflated, and the patient is turned into a supine position.
The tendon transfer is performed through a posteromedial incision in the line of the posterior tibial tendon. The flexor retinaculum is opened, and the ruptured posterior tibial tendon is inspected. The proximal posterior tibial tendon is used for a side-to-side tenodesis to the flexor digitorum longus tendon if there is elasticity of the tendon. If the tendon has no excursion, it is transected and left free behind the medial malleolus. The tendon sheath of the flexor digitorum longus tendon is then opened and exposed beneath the arch of the foot where it crosses superficial to the flexor hallucis longus tendon at the level of the naviculocuneiform joint. Plantar retraction of the abductor hallucis brevis muscle belly improves exposure. Care is taken to avoid injury to the plantar vessels and medial plantar nerve that are in close proximity. Since the flexor digitorum longus is transected proximal to the interconnection of the flexor digitorum longus and the flexor hallucis longus tendon, tenodesis of the stump of the flexor digitorum longus to the flexor hallucis longus was not performed. A 4.5-mm drill hole is made in the navicular 1 cm lateral to its medial border, and the tendon is passed through the drill hole from plantar to dorsal using a suction tip catheter[28]. Before suture of the tendon transfer, with the foot held inverted and slightly plantarflexed, the capsule of the talonavicular joint, if torn, is plicated by excising a vertical ellipse approximately 6 mm in diameter. The flexor digitorum longus tendon is then sutured in this position to the adjacent periosteum. If the stump is long enough, additional strength of repair is achieved by suturing the tendon back on itself. The tendon is sutured under maximum tension with the foot/ankle in plantarflexion of 15 degrees and inversion of 15 degrees.
Additional surgeries were performed in forty-nine patients, including repair of a tear of the spring ligament, talonavicular capsule, or deltoid ligament (forty-six patients), lengthening of the Achilles tendon (twenty-six patients), correction of hallux valgus deformity (five patients), and arthrodesis of the first tarsometatarsal joint (four patients). The indication for lengthening of the Achilles tendon was specifically for patients who had an equinus contracture of 10 degrees or more while the subtalar joint was held in the neutral position. If the lengthening needed to be performed, first we proceeded with the tendon Achilles lengthening and we continued with the main course of the operative procedure. The tendon Achilles lengthening was performed using the triple hemisection step cut technique of Hoke as previously described[13,14].
The operative findings varied. The ten patients who had seronegative inflammatory disease had a proliferative synovial membrane that adhered to the tendon. In these patients, the tendon was found to be attenuated and to contain longitudinal fissures, and a chronic nonspecific infiltrate was noted histologically. In the remaining 119 patients who had degenerative rupture of the tendon, the tendon sheath was edematous and thickened. Fibrous adhesions usually were present and often extended posteriorly from the inner (medial) aspect of the tendon. The degenerative tear was commonly present 1 cm distal to the medial malleolus, with partial or complete rupture of the tendon occurring approximately 2 cm proximal to the tubercle of the navicular. In most cases, the scarred tendon was adhered to the tendon sheath. Longitudinal fissures commonly were found in the posterior aspect of the tendon that lies in proximity to the deeper soft tissues and tendon sheath.
Of the 129 patients, forty-eight had complete disruption of the posterior tibial tendon without any visible presence of the tendon either proximally or distally; thirty-nine had complete rupture of the tendon with visible tendon ends but no excursion of the proximal tendon when pulling distally; twenty-three had complete rupture of the tendon but with maintenance of some proximal excursion; eleven had grossly visible longitudinal fissuring and attritional intrasubstance tears but without any proximal excursion; and, in addition to edema and tenosynovitis, eight had intratendinous degeneration on the deep aspect of the tendon, but the tendon maintained full excursion when it was pulled in a distal direction. We noted additional surgical pathology in the adjacent supportive structures, including eighteen tears of the spring ligament, twenty-one isolated tears of the talonavicular capsule, and seven tears of the deltoid ligament. In those patients where a tear of the spring ligament was present, there was continuity with and extension of the tear into the talonavicular capsule.
Postoperative Treatments
During the first four years of this series, fifty-two patients were immobilized in equinus and varus for four weeks, and then a more plantigrade position was assumed in a cast or removable boot over the subsequent four weeks. Bearing of weight was not permitted for six weeks, followed by weightbearing as tolerated. During the latter part of this series and continuing until the present, the remaining seventy-seven patients were allowed to commence range of motion exercises at two weeks, a cast was not used, and weightbearing was permitted commencing at two weeks in a walker boot with the foot positioned in slight inversion and 10 degrees of equinus. A medial longitudinal arch felt pad was inserted into the boot, and the hinge on the boot was set at 10 degrees of equinus. At eight to twelve weeks, the boot is discontinued, and all patients wore a stirrup ankle brace for an additional four weeks, during which time patients perform strengthening exercises either in a supervised physical therapy program or at home. Walking, cycling, and other strengthening exercises are commenced at three months, and other sports activities are permitted by four months, provided the patients are able to perform repetitive heel rises without pain.
Each of the 129 patients in this study was examined in a systematic manner as part of normal follow-up by one of the authors [A.B.] at a mean of 5.2 years after surgery (range, three to eight years), with objective and subjective criteria used for determining the outcome of treatment. This careful follow-up was considered necessary by the authors because the surgical procedures were relatively new, and detailed evaluation of patient outcomes was required.
The AOFAS hindfoot scale and the Short Form Health Survey SF-36 was used to evaluate patient satisfaction and hindfoot function of each patient, although scores were not assigned retrospectively. Although preoperative scores were available for a limited number of patients, it has been demonstrated that AOFAS scores assigned to patients retrospectively are not valid[42]. We determined patients' level of satisfaction; we also determined functional status using a questionnaire and clinical examination and assessed work habits, recreational ability, level and intensity of postoperative pain, walking endurance, and, if any supportive devices were used, the functioning of braces or orthoses.
Radiographic assessment was performed using standardized weightbearing anteroposterior and lateral radiographs for all patients, which included their preoperative radiographs as well as the postoperative radiographs noted below. On the anteroposterior view, the parameters studied were the talus first metatarsal angle and the talonavicular coverage angle. On the lateral radiograph, the talus first metatarsal angle and the height of the plantar cortex of the medial cuneiform to the floor were measured and compared with the preoperative radiographs. In addition, we compared the postoperative radiographs taken at 6 months with those taken at the final follow-up examination to determine if there was loss of correction over time.
The isokinetic strength of 121 patients was evaluated using a dynamometer designed for torque measurements of concentric and eccentric muscle action (Kinetic Communicator, Chattanooga Group, Inc., Chattanooga, TN). The isokinetic inversion and plantar flexion power and strength was compared with the contralateral limb to measure inversion and plantarflexion, concentric and eccentric muscle power, and strength. The power and strength was determined to be either normal or symmetric with the opposite limb, mildly weak (<25% loss of strength) or moderately weak (>50% loss of strength).
RESULTS
Of the 129 patients in the study, 118 (92 percent) were entirely satisfied with the outcome of the surgical treatment and indicated that they would undergo a similar procedure again. Seven patients were partially satisfied, and four were dissatisfied with the outcome of the procedure. Of the eleven patients who were not satisfied, five had ruptures associated with systemic disorders (three with seronegative, one with Marfan, and one with Ehlers-Danlos disorder), and four of these five patients had more than 30 percent radiographic uncovering of the talonavicular joint preoperatively. Of the remaining six patients who were not satisfied, four had similar increased abduction of the forefoot radiographically.
Walking and Activities
With respect to prolonged walking and activities, 107 patients experienced no pain or discomfort and were not in any way limited; eleven experienced mild pain or discomfort on an intermittent basis that did not limit their activities, seven noted similar limitations with activities they had experienced before surgery, and four felt that they were worse off with respect to activities and ambulation than they had been before surgery. Nine patients resumed recreational jogging, including three patients who returned to competitive long-distance running, one of whom completed the marathon distance. Of the 129 patients, 125 (97 percent) experienced pain relief and 112 (87 percent) had improvement of function. When we evaluated pain relief and return to function, 121 (94 percent) patients reported a noticeable improvement at a mean of seven months (range, three to nine months) after surgery and continued improvement for a mean of an additional five months (range, two to eleven months). Fourteen months was the mean duration of improvement noted subjectively by the patients until they reached a functional plateau after surgery (range, nine to eighteen months). Recreational interests and activities improved dramatically in 115 patients (89 percent), remained the same for ten patients (8 percent), and worsened in four patients (3 percent). Although we attempted to note a change in work status, this was not easy to define because most these patients had fairly sedentary work styles before surgery. Of the 129 patients, seventy-three (56 percent) had a full-time or part-time job. Employment and work activities remained the same for forty-eight of these patients (65 percent), five patients (7 percent) noted a marked improvement in their ability to work, and twenty patients (28 percent) noted a decrease in their work activities. We did not correlate the decrease in work activities for these twenty patients with satisfaction with the outcome of treatment or with decrease in pain and discomfort.
Shoe Wear
Shoe wear was not limited nor restricted in any manner for 109 patients (84 percent), and these patients did not require any shoe modification; thirteen patients (10 percent) felt more comfortable in a stiff-soled shoe, and five patients (4 percent) routinely used a more rigid supportive shoe. Twenty-seven patients used a soft accommodative orthotic arch support, and nine patients used more rigid orthotic support for routine activities. Two patients continued to wear a hinged foot and ankle orthosis, and eventually both of them were treated with triple arthrodesis.
AOFAS Score
The AOFAS hindfoot scale was used to evaluate each patient, although preoperative scores were not assigned retrospectively. The mean AOFAS score at the time of the follow-up examination was 79 points (range, 54 to 93). In this examination, we paid particular attention to the patient’s ability to stand unsupported on one foot and repetitively perform a single heel rise, noting that 114 patients (88 percent) were able to perform this function. Each patient was evaluated in follow-up by a single examiner, and the patients were asked to perform the repetitive heel rise five times while balancing with the outstretched finger of the examiner’s hand. Seven patients were able to perform a single heel rise although not repetitively, and eight were unable to perform a single heel rise.
SF-36 Health Survey
In our study we used also the Short Form Health Survey SF-36 as an outcome assessment method to determine the effectiveness of this particular surgical procedure in terms of patients' physical status and general satisfaction. We used the Physical and Mental Component Summary scales (PCS, MCS) that this survey includes. We identified 118 patients who had completed the SF-36 forms preoperatively, and these patients completed another short form health survey SF-36 postoperatively together with completing the other evaluations according to the standard protocol of this study. The preoperative patient population was stratified into three groups. The mean was PCS 32 +/- (standard deviation, 9.4). We noted a low-function group (PCS < 19), a middle-function group (20 < PCS < 38), and a high-function group (PCS > 39) based on the three levels of limitation defined on the SF-36 survey form. According to the preoperative and postoperative SF-36 survey results, we had marked improvement in Physical Scales after surgery. The low-functioning and middle-functioning groups had dramatic improvement of physical health after the operation. In the high-functioning group, the operation was less effective at improving physical health, possibly reflecting overall findings such as the increased effectiveness of the operation for those over 45 years old. In the low-functioning and middle-functioning groups, 54 percent (47 of 87 patients) of the patient population was over the age of 45, whereas 74 percent (23 of 31 patients) of the high-functioning group was under the age of 45. This procedure appears to be more effective in improving the quality of life of patients with PCS scores < 39 in the SF-36 Health survey.
Radiographic Measurements
Of the 129 patients, 125 (97 percent) demonstrated radiographic improvement in the parameters measured at six months postoperatively, and 118 (92 percent) retained this improvement in this follow-up study. The radiographic measurements we studied were on the anteroposterior projection (the talonavicular coverage and the talo-metatarsal angles) and on the lateral projection (the talus-first metatarsal angle and the height of the medial cuneiform to the floor). On the anteroposterior projection, there was improvement in the talonavicular coverage and the talo-metatarsal angles. Statistical analysis was performed using an analysis of variance (p = 0.017). The anteroposterior talometatarsal angle improved from a preoperative mean value of 25 degrees (range, 0 degrees to 49 degrees) to a postoperative mean value of 6 degrees (range, –11 degrees to 28 degrees), a mean improvement of 21 degrees (p = 0.018). The mean anteroposterior talonavicular coverage angle was 37 degrees preoperatively (range, 7 degrees to 57 degrees), with a mean postoperative improvement of 16 degrees (range, 0 degrees to 45 degrees) in this parameter. Five patients showed a slight deterioration of the anteroposterior talonavicular coverage angle. These were patients who had a markedly deformed foot, severe valgus, and external rotation deformity of the foot. We noticed in the latest radiographs of the long-term study a mean deterioration of the anteroposterior talonavicular coverage angle of 6 degrees (range, 4 degrees to 9 degrees) in a mean 5.8 years follow-up time of these patients. On the lateral projection, the mean talus-first metatarsal angle of –27 degrees preoperatively (range, –45 degrees to –9 degrees) improved to a mean value of –12 degrees (range, –33 degrees to 0 degrees) postoperatively, a mean improvement of 12 degrees. The height of the medial cuneiform to the floor increased from a mean preoperative value of 7 mm (range, 0 to 16 mm) to a mean postoperative value of 19 mm (range, 12 to 30 mm). The five patients whose preoperative deformities were the most severe showed no improvement in the medial cuneiform to floor distance and had maximum deformity also at the naviculocuneiform joint. Six patients demonstrated deterioration of the height of the medial cuneiform to floor distance of a mean of 8 mm (range, 12 to 5 mm) in a mean follow-up time of 5.2 years. Of these six patients, four weighed over 270 pounds, and two had underlying systemic pathology. Eight of the eleven patients who did not demonstrate an improvement in radiographic parameters at final follow-up had a worse subjective outcome, including dissatisfaction with the procedure and lower AOFAS scores. On an individual basis, the value that showed a consistent and grossly noticeable improvement after the surgery was the height of the medial arch as judged from the distance of the medial cuneiform to the floor.
Isokinetic Function
Using the KinCom apparatus, we examined the eccentric and the concentric muscle power and strength of the invertors and plantarflexors of both feet in 121 patients. The remaining eight patients either could not comply with the instructions for use of the apparatus or could not be scheduled for the examination. Isokinetic inversion strength was noted to be symmetric with the opposite limb in 91 patients, mildly weak in 21, and moderately weak in 9. Plantarflexion isokinetic power was noted to be symmetric with the opposite limb in 95 patients, mildly weak in 18, and moderately weak in 8.
Subtalar Joint Motion
The subtalar motion was examined subjectively by one investigator [A.B.], by holding the ankle in the neutral position and passively supinating and pronating the rest of the foot with the other hand. The motion was defined as either normal, slightly decreased (0-25 percent), or moderately decreased (25-50 percent). Motion of the subtalar joint was normal in 56 patients (44 percent), slightly decreased in 66 patients (51 percent), and moderately decreased in 7 patients (5 percent). There was no patient with absent subtalar motion.
Complications
There were seven severe complications in six patients. One patient developed progressive hindfoot valgus deformity one year after surgery and was treated with a triple arthrodesis. The deformity in two patients was overcorrected, resulting in heel varus with lateral foot pain and a sense of ankle instability. It likely that the varus position of the heel was due to a malunion of the calcaneal osteotomy in conjunction with overtightening of the flexor digitorum longus tendon transfer. These two patients were treated at eighteen and twenty-two months with a lateral closing wedge calcaneus osteotomy. Three patients experienced symptomatic sural neuritis; of these, one underwent transection of the neuroma and burial of the stump in the peroneus brevis muscle, and the remaining two were treated with local desensitization physical therapy modalities that were successful in alleviating the sensitivity, although the numbness persisted. One patient had weakness and severe calf muscle atrophy resulting from overlengthening of the Achilles tendon, which resolved only partially with physical therapy and strengthening exercises. There were five patients who experienced numbness (three transient, two permanent) in the distribution of the medial plantar nerve. Four patients initially experienced lateral foot pain under the fifth metatarsal and cuboid; however, these symptoms abated seven to eleven months after the operation for all four patients. No patients developed deep wound infections, but after surgery, five were treated for superficial cellulites, which resolved with oral antibiotic therapy and topical wound care.
DISCUSSION
The acquired flatfoot deformity that develops as a result of a tear of the tibialis posterior tendon highlights the important function of this muscle as a dynamic stabilizer of the medial arch of the foot. The synergistic function of the tibialis posterior and gastrocnemius-soleus muscles deserves special emphasis, since rupture of the posterior tibial tendon is followed by a change in the axis of the Achilles tendon, leading to a progressively worsening flatfoot deformity. In patients with rupture of the posterior tibial tendon followed by pes planovalgus deformity, the Achilles tendon shifts laterally with the calcaneus, ultimately moving lateral to the axis of the subtalar joint. As a result of dynamic muscle forces, the deformity slowly worsens, compounded by passive elongation of the capsuloligamentous support about the talonavicular joint.
We focused in this study on a specific treatment for stage II rupture of the posterior tibial tendon, which should be reviewed comparison with alternative procedures for correction of similar deformity. Some procedures rely upon joint stabilization with arthrodesis, and some emphasize correction using tendon transfer augmented with osteotomy of the hindfoot. Lengthening osteotomy through the calcaneus between the anterior and middle facets (the Evans procedure) has been reported with good short-term results in several series of patients. This procedure seems to be effective, especially when combined with tendon reconstruction medially.[6,12,37,39,41] [1]. A subtalar arthrodesis has been performed with acceptable results, although clearly the benefits of stabilization are achieved at the expense of hindfoot motion[19,21,25]. Furthermore, reports indicate limited correction of deformity, and approximately half of the patients had some continued pain[21]. Other isolated fusions of the hindfoot joints have been performed, including the talonavicular fusion and the calcaneocuboid fusion[3,11]. Malunion, the need for additional procedures including a bone graft, calcaneocuboid nonunions[1], and injury to the sural nerve are additional problems following calcaneocuboid arthrodesis. Clinical and biomechanical studies have shown that approximately 50 percent of the subtalar motion is lost with this fusion[35]. A final option for the stage II posterior tibial tendon is triple arthrodesis, which removes any remaining hindfoot motion but provides stability with a very low risk of malunion or nonunion[9,16,36,40,44].
The above procedures relied upon arthrodesis of one sort or another to gain and maintain stability of the hindfoot. As an alternative, investigators have attempted to balance the abnormal muscle forces by tendon transfer, replacing the torn posterior tibial tendon with either the flexor hallucis longus [8] or the flexor digitorum longus tendons [26]. The rationale behind these tendon substitutions was to use a muscle that was in-phase to substitute for the dysfunctional posterior tibial tendon and to provide a reasonable antagonist to the eversion force of the peroneus brevis muscle. These authors noted symptomatic improvement for the majority of their patients, although little correction of the arch of the foot was noted.
Tendon substitution is important, but the strength of the flexor digitorum longus tendon is far less than that of the posterior tibial tendon, and it was partly with this in mind that we initially began using the medial translational calcaneal osteotomy with the tendon transfer. It seemed logical to us to combine the satisfactory early results reported for transfer of the flexor digitorum longus or the flexor hallucis longus into the navicular with those of medial translation of the calcaneus. The potential for correction of the valgus position of the calcaneus, and indirectly the lateralized axis of the Achilles tendon with calcaneal osteotomy has been recognized by numerous authors. [7,22,23]. The improvement of the arch does not occur as a result of tightening of the plantar fascia, because both medial calcaneal osteotomy and lateral column lengthening relax the plantar fascia[15]. The correction of the arch with the medial calcaneal osteotomy is the result of a medial shift of the Achilles tendon, which then acts as an invertor on the subtalar joint. This effectively has the effect of a double tendon transfer medially, with further improvement of the arch as a result of ground reaction forces.[34] The amount of medial shift of the calcaneus required to produce this effect is not known, although the decision initially to use 1cm was based upon the average width of the calcaneus and the need for a stable osteotomy that was easy to secure with internal fixation. Two patients developed a varus deformity of the hindfoot, presumably from overcorrection of the osteotomy. Axial radiographs of the hindfoot demonstrated a 1-cm shift for these patients, but in both there was in addition slight varus tilting of the tuberosity of the calcaneus. It is worth repeating that eight of the eleven patients who did not demonstrate an improvement in radiographic parameters at final follow-up had a worse subjective outcome, including dissatisfaction with the procedure and lower AOFAS scores. This an important finding, since one would assume that if the subjective outcome of these eight patients were similar to those with improved radiographic indices of the arch, that a tendon transfer alone would reliably be sufficient to improve patient function and satisfaction with the outcome of treatment.
This procedure is ideally suited for the patient with a flexible flatfoot, insignificant fixed forefoot supination, and less than 30% uncovering of the talonavicular joint. We have experienced problems with the described procedure in patients with more extensive uncovering of the talonavicular joint. For these patients, correction of the deformity postoperatively has not been as successful as for the majority of patients described in this series. These feet are typically flexible, and the deformity is passively correctable as for other patients with stage II deformity. However, for these patients something more than a medial translational osteotomy is required to obtain satisfactory correction. Correction can be obtained with a triple arthrodesis but this is excessive, and correction is ideally obtained with lengthening of the lateral column either through the neck of the calcaneus or as an arthrodesis of the calcaneocuboid joint.
An interesting related issue is whether the Achilles tendon should be routinely lengthened if an equinus contracture is present. With examination of the acquired flatfoot, we note a marked eversion force on the talonavicular joint when attempting to passively dorsiflex the foot in the presence of a equinus contracture. Our concern is therefore the likelihood of recurrent deformity after surgical correction if the Achilles tendon is not lengthened. We did not analyze our results separately for patients who were treated with or without an Achilles tendon lengthening. We did experience one severe complication as a result of lengthening of the Achilles tendon, and clearly weakness of plantarflexion must exist after lengthening for a period of time, perhaps permanently. However, the strength in plantarflexion and in inversion was noted to be symmetric with the opposite limb in 95 of the 121 patients examined using isokinetic testing, although we did not note whether there was weakness or deformity in the opposite limb at the time of strength testing. It would have been useful to know whether or not patients with greater strength postoperatively had a partial and not a complete rupture of the tendon at the time of surgery. In patients with partial rupture but no scarring of the remaining proximal tendon, a side-to-side tenodesis of the flexor digitorum longus to the posterior tibial tendon is performed provided that mobility of the remaining posterior tibial tendon is present proximally. Unfortunately, this was not evaluated in this series of patients.
The improvement in the talus-first metatarsal angle, the talonavicular coverage, and the medial cuneiform height is likely the result of the dynamic muscle as well as ground reaction forces on the hindfoot. In our series, we had improvement of the anteroposterior and lateral talus-first metatarsal angles by 21 and 12 degrees, respectively. The talonavicular coverage angle improved 16 degrees, and the medial cuneiform-floor height improved by 19 mm. Most importantly, there was no loss of correction over time. We compared the radiographic results at final follow-up examination with those obtained at six months after surgery, and we noted that if correction of deformity was present at six months, then this was maintained at final follow-up. This is important finding, since if failure occurs, it would seem to do so early and not as a result of a later attritional process. Of the 129 patients, 125 (97 percent) demonstrated radiographic improvement in one or more of the parameters measured at six months postoperatively, and 118 (92 percent) retained this improvement at final follow-up. The cause for early failure of correction is not entirely clear. As noted above, this procedure may not be ideal for patients with more extensive deformity including greater uncovering of the talonavicular joint. As a result of the increased abduction of the forefoot in these patients, there is more extensive tearing of the secondary supportive ligaments, including the spring ligament and the talonavicular capsule. When we examined the group of patients who did not do as well as the majority in this series, it was apparent that these patients had a level of deformity beyond the scope of this procedure despite their having met the clinical inclusion criteria. This clinical and radiographic failure occurred despite repair of the talonavicular capsule and the spring ligament in those patients in whom a tear was identified. Forty-six patients required a repair of the spring ligament, talonavicular capsule, or deltoid ligament, and eight of the eleven patients who were dissatisfied with the outcome of treatment were in this group.
This is the first long-term series examining the results of medial displacement calcaneus osteotomy in addition to flexor digitorum longus tendon transfer for correction of flexible flatfoot deformity as a result of posterior tibial tendon rupture. It is a relatively simple procedure that offers static and dynamic stabilization of the medial arch of the foot and has resulted in long- term overall improvement in the radiographic parameters studied, which has not been the experience with the tendon transfer alone. Surgical correction of the stage II posterior tibial tendon rupture should attempt to maintain flexibility of the foot, to restore motor function, to reduce the deforming forces, to give pain relief, and to improve the medial longitudinal arch of the foot. The combined procedure of flexor digitorum longus tendon transfer and translational osteotomy of the calcaneus can well achieve these objectives without diminution of correction over time.
REFERENCES
1. Chi, T. D.; Toolan,B.C.; Sangeorzan,B.J.; and Hansen,S.T., Jr.: The lateral column lengthening and medial column stabilization procedures. Clin. Orthop., 365:81-90, 1999.
2. Chu, I.-T.; Myerson,M.S.; Nyska,M.; and Parks,B.G.: Experimental flatfoot model: the contribution of dynamic loading. Foot Ankle Int., 22:220-225, 2001.
3. Clain, M. R., and Baxter,D.E.: Simultaneous calcaneocuboid and talonavicular fusion. Long-term follow-up study. J. Bone Joint Surg., 76B:133-136, 1994.
4. Conti, S.; Michelson,J.; and Jahss,M.: Clinical significance of magnetic resonance imaging in preoperative planning for reconstruction of posterior tibial tendon ruptures. Foot Ankle, 13:208-214, 1992.
5. Funk, D. A.; Cass,J.R.; and Johnson,K.A.: Acquired adult flat foot secondary to posterior tibial-tendon pathology. J. Bone Joint Surg., 68A:95-102, 1986.
6. Ginsburg, W. W., and Cohen,M.D.: Peripheral arthritis in ankylosing spondylitis. A review of 209 patients followed up for more than 20 years. Mayo Clin. Proc., 58:593-596, 1983.
7. Gleich, A.: Beitrag zur operativen plattfussbehandlung. Arch Klin Chir, 46:358-362, 1893.
8. Goldner, J. L.; Keats,P.K.; Bassett,F.H., III; and Clippinger,F.W.: Progressive talipes equinovalgus due to trauma or degeneration of the posterior tibial tendon and medial plantar ligaments. Orthop. Clin. North Am., 5:39-51, 1974.
9. Graves, S. C.; Mann,R.A.; and Graves,K.O.: Triple arthrodesis in older adults. Results after long-term follow-up. J. Bone Joint Surg., 75A:355-362, 1993.
10. Graves, S. C., and Stephenson,K.: The use of subtalar and triple arthrodesis in the treatment of posterior tibial tendon dysfunction. Foot Ankle Clin., 2:319-328, 1997.
11. Harper, M. C., and Tisdel,C.L.: Talonavicular arthrodesis for the painful adult acquired flatfoot. Foot Ankle Int., 17:658-661, 1996.
12. Hintermann, B.; Valderrabano,V.; and Kundert,H.P.: Lengthening of the lateral column and reconstruction of the medial soft tissue for treatment of acquired flatfoot deformity associated with insufficiency of the posterior tibial tendon. Foot Ankle Int., 20:622-629, 1999.
13. Hoke, M.: An operation for stabilizing paralytic feet. J. Orthop. Surg., 3:494-505, 1921.
14. Hoke, M.: An operation for the correction of extremely relaxed flat feet. J. Bone Joint Surg., 13:773-783, 1931.
15. Horton, G. A.; Myerson,M.S.; Parks,B.G.; and Park,Y.-W.: Effect of calcaneal osteotomy and lateral column lengthening on the plantar fascia: a biomechanical investigation. Foot Ankle Int., 19:370-373, 1998.
16. Horton, G. A., and Olney,B.W.: Triple arthrodesis with lateral column lengthening for treatment of severe planovalgus deformity. Foot Ankle Int., 16:395-400, 1995.
17. Jahss, M. H.: Spontaneous rupture of the tibialis posterior tendon: clinical findings, tenographic studies, and a new technique of repair. Foot Ankle, 3:158-166, 1982.
18. Johnson, J. E.; Cohen,B.E.; Digiovanni,B.F.; and Lamdan,R.: Subtalar arthrodesis with flexor digitorum longus transfer and spring ligament repair for treatment of posterior tibial tendon insufficiency. Foot Ankle Int., 21:722-729, 2000.
19. Johnson, K. A.: Tibialis posterior tendon rupture. Clin. Orthop., 177:140-147, 1983.
20. Johnson, K. A., and Strom,D.E.: Tibialis posterior tendon dysfunction. Clin. Orthop., 239:196-206, 1989.
21. Kitaoka, H. B., and Patzer,G.L.: Subtalar arthrodesis for posterior tibial tendon dysfunction and pes planus. Clin. Orthop., 345:187-194, 1997.
22. Koutsogiannis, E.: Treatment of mobile flat foot by displacement osteotomy of the calcaneus. J. Bone Joint Surg., 53B:96-100, 1971.
23. Lord, J. P.: Correction of extreme flatfoot. Value of osteotomy of os calcis and inward displacement of posterior fragment (Gleich operation). JAMA, 81:1502-1507, 1923.
24. Mann, R. A.: Acquired flatfoot in adults. Clin. Orthop., 181:46-51, 1983.
25. Mann, R. A.; Beaman,D.N.; and Horton,G.A.: Isolated subtalar arthrodesis. Foot Ankle Int., 19:511-519, 1998.
26. Mann, R. A., and Thompson,F.M.: Rupture of the posterior tibial tendon causing flat foot. Surgical treatment. J. Bone Joint Surg., 67A:556-561, 1985.
27. Marks, R. M.: Posterior tibial tendon reconstruction with medial displacement calcaneal osteotomy. Foot Ankle Clin., 1:295-313, 1996.
28. Melamed, E. A.; Myerson,M.S.; and Schon,L.C.: A review of tendon passing techniques and introduction of a new method using a suction tip. Foot Ankle Int., 21:693-696, 2000.
29. Michelson, J.; Conti,S.; and Jahss,M.: Survivorship analysis of tendon transfer surgery for posterior tibial tendon rupture. Orthop. Trans., 16:30, 1992.
30. Myerson, M.; Solomon,G.; and Shereff,M.: Posterior tibial tendon dysfunction: its association with seronegative inflammatory disease. Foot Ankle, 9:219-225, 1989.
31. Myerson, M. S.: Adult acquired flatfoot deformity. Treatment of dysfunction of the posterior tibial tendon. J. Bone Joint Surg., 78A:780-792, 1996.
32. Myerson, M. S., and Corrigan,J.: Treatment of posterior tibial tendon dysfunction with flexor digitorum longus tendon transfer and calcaneal osteotomy. Orthopedics, 19:383-388, 1996.
33. Myerson, M. S.; Corrigan,J.; Thompson,F.; and Schon,L.C.: Tendon transfer combined with calcaneal osteotomy for the treatment of posterior tibial tendon insufficiency: a radiological investigation. Foot Ankle Int., 16:712-718, 1995.
34. Nyska, M.; Parks,B.G.; Chu,I.-T.; and Myerson,M.S.: The contribution of the medial calcaneal osteotomy to the correction of flatfoot deformities. Foot Ankle Int., 22:278-282, 2001.
35. Otis, J. C.; Deland,J.T.; Kenneally,S.; and Chang,V.: Medial arch strain after medial displacement calcaneal osteotomy: an in vitro study. Foot Ankle Int., 20:222-226, 1999.
36. Pell, R. F.; Myerson,M.S.; and Schon,L.C.: Clinical outcome after primary triple arthrodesis. J. Bone Joint Surg. Am., 82:47-57, 2000.
37. Phillips, G. E.: A review of elongation of os calcis for flat feet. J. Bone Joint Surg., 65B:15-18, 1983.
38. Sammarco, G. J., and Hockenbury,R.T.: Treatment of stage II posterior tibial tendon dysfunction with flexor hallucis longus transfer and medial displacement calcaneal osteotomy. Foot Ankle Int, 22:305-312, 2001.
39. Sangeorzan, B. J.; Mosca,V.; and Hansen,S.T., Jr.: Effect of calcaneal lengthening on relationships among the hindfoot, midfoot, and forefoot. Foot Ankle, 14:136-141, 1993.
40. Sangeorzan, B. J.; Smith,D.; Veith,R.; and Hansen,S.T., Jr.: Triple arthrodesis using internal fixation in treatment of adult foot disorders. Clin. Orthop., 294:299-307, 1993.
41. Sangeorzan, B. J.; Wagner,U.A.; Harrington,R.M.; and Tencer,A.F.: Contact characteristics of the subtalar joint: the effect of talar neck misalignment. J. Orthop. Res., 10:544-551, 1992.
42. Toolan, B. C.; Wright,Q., V; Cunningham,B.J.; and Brage,M.E.: An evaluation of the use of retrospectively acquired preoperative AOFAS clinical rating scores to assess surgical outcome after elective foot and ankle surgery. Foot Ankle Int, 22:775-778, 2001.
43. Turan, I., and Lindgren,U.: Metatarsal osteotomy using internal fixation with compression screws. J. Foot Surg., 28:116-119, 1989.
44. Wetmore, R. S., and Drennan,J.C.: Long-term results of triple arthrodesis in Charcot-Marie-Tooth disease. J. Bone Joint Surg., 71A:417-422, 1989.
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