Radiographic Analysis of the Lateral Column Lengthening Procedure in Stage II Adult Acquired Flatfoot Deformity

Adult acquired flat foot deformity (AAFD) is a progressive, tri-planar deformity involving collapse of the medial longitudinal arch, valgus deformity of the rear foot, and abduction of the mid-foot on the rear foot. There are a wide variety of surgical treatment options for this deformity, including lateral column lengthening (LCL) which results in tri-planar correction of AAFD. We retrospectively reviewed weightbearing preoperative radiographs and weight-bearing 6-week postoperative radiographs of 34 patients with stage II AAFD who underwent LCL (with and without concurrent procedures) with a minimum of 1-year of follow up. Outcomes, including complications and postoperative differences in 6 types of angle measurements were evaluated. Radiographic evaluation showed statistically significant differences in preoperative and postoperative measures in the following angles: calcaneal inclination, Meary's, Simmons, talocalcaneal, and metatarsus adductus (each p ≤ .05). Postoperative Engel's angle difference did not reach statistical significance (p = .07). Paired t tests showed TN coverage angles increased greater with LCL plus a Cotton osteotomy as compared to isolated LCL. Additionally, there was no significant difference in TN coverage angle based on LCL graft size (p = .20). Furthermore, the distance of the osteotomy from the calcaneocuboid joint on anteroposterior and lateral radiographs did not significantly predict TN coverage angle change. Our study suggests that LCL corrects AAFD in three planes while decreasing the metatarsus adductus angle. LCL appears to be more effective when performed with a Cotton osteotomy. Wedge size (6 mm, 8 mm, 10 mm) and osteotomy location did not demonstrate a relationship with postoperative TN coverage angle or incidence of lateral column overload.

A Modified Extra-articular Lateral Column Lengthening Procedure for Adult Acquired Flatfoot Deformity

BACKGROUND

Lateral column lengthening (LCL), originally described by Evans, is an established procedure to correct stage II adult acquired flatfoot deformity (AAFD). However, the relative position between the facets is violated, and other problems may include nonunion, malunion, and calcaneocuboid (CC) joint subluxation. Herein, we report a modified extra-articular technique of LCL with hockey-stick osteotomy, which preserves the subtalar joint as a whole, increases bony apposition to enhance healing ability, and preserves the insertion of the calcaneofibular ligament to stabilize the posterior fragment to promote adduction of the forefoot.

METHODS

We retrospectively recruited 24 patients (26 feet) with stage II AAFD who underwent extra-articular LCL. The mean age was 55.7 ± 15.7 years, and the mean follow-up period was 33.4 ± 12.1 months. Associated procedures of spring ligament repair/reconstruction and posterior tibial tendon plication or flexor digitorum longus transfer were routinely performed and may also include a Cotton osteotomy, heel cord lengthening, or hallux valgus correction. Clinical and radiographic outcomes at the final follow-up were compared with the preoperative assessments.

RESULTS

All patients achieved calcaneus union within 3 months of operation. The VAS pain score improved from 5.3 ± 0.75 preoperatively to 1.2 ± 0.79 at the final follow-up (P < .001), and the AOFAS Ankle-Hindfoot Scale from 63.5 ± 8.5 to 85.8 ± 4.8 points (P < .001). The radiographic measurements significantly improved in terms of the preoperative vs final angles of 8.9 ± 5.3 vs 15.2 ± 3.6 degrees for calcaneal pitch (P < .001), 20.5 ± 9.2 vs 4.9 ± 4.8 degrees for Meary angle (P < .001), 46.5 ± 5.2 vs 41.9 ± 3.2 degrees for lateral talocalcaneal angle (P < .001), 23.9 ± 8.5 vs 3.9 ± 3.1 degrees for talonavicular coverage angle (P < .001), and 18.2 ± 9.2 vs 7.3 ± 5.0 degrees for talus-first metatarsal angle (P = .002). The CC joint subluxation percentage was 7.0% ± 5.4% preoperatively compared with 8.5% ± 2.4% at the final follow-up (P = .101). No case showed progression of CC joint arthritis or CC joint subluxation (>15% CC joint subluxation percentage). One case showed transient sural nerve territory paresthesia, and 1 had pin tract infection. Three cases had lateral foot pain, which could be relieved by custom insoles.

CONCLUSION

Modified extra-articular LCL as part of AAFD correction is a feasible alternative technique without subtalar joint invasion and may be associated with less CC joint subluxation compared with the Evans osteotomy.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

The Plantar Fascia Talar Head Correlation: A Radiographic Parameter With a Distinct Threshold to Validate Flatfoot Deformity and Its Corrective Surgery on Conventional Weightbearing Radiographs

BACKGROUND

Corrective surgery for flexible flatfoot deformity (FD) remains controversial, and one of the main reasons for this is the lack of standardized radiographic measurements to define an FD. Previously published radiographic parameters to differentiate between a foot with and without an FD do not have a commonly accepted and distinct threshold.

METHODS

The plantar fascia-talar head correlation (PTC) with its defined threshold was assessed by measuring the distance between the medial border of the plantar fascia and the center of the talar head (DPT) on conventional dorsoplantar and lateral weightbearing radiographs; the authors were blinded to the clinical diagnosis of the 189 patients' first visits. Feet were sorted into groups with and without an FD based on their clinical examination. The effect of operative corrections of FD on the PTC was retrospectively evaluated on an additional 38 patients.

RESULTS

The sensitivity of the PTC was 0.98 (95% CI: 0.9-1) and specificity 0.96 (95% CI: 0.92-0.98), respectively, to identify an FD, consistent with the clinical examination. Thirty-five of 38 surgeries sufficiently corrected the FD and the PTC comparable to that in subjects without an FD. Three corrections with a residual FD did not adequately correct the PTC.

CONCLUSION

The PTC is a reliable radiographic parameter with a distinct threshold that is sensitive and specific for the differentiation of feet with and without an FD including feet with and without residual FD after corrective surgery. The PTC is applicable to monitor the needed intraoperative amount of correction using simulated weightbearing fluoroscopy.

LEVEL OF EVIDENCE

Level III, diagnostic.

Biomechanical Evaluation of a Cadaveric Flatfoot Model and Lateral Column Lengthening Technique

Patients with adult acquired flatfoot have progressive worsening of bony alignment with many being unable to perform a heel rise. Following reconstruction, pathologic skeletal alignment is corrected and the ability to perform a heel rise is often restored. The purpose of this study was to evaluate the relationship between forefoot liftoff forces and skeletal alignment in a cadaveric flatfoot model by assessing the effect of sequential lengthening of the lateral column using an Evans-type calcaneal osteotomy. Bony alignment was measured in 8 cadaveric specimens with the use of a 3-dimensional digitizing system. Transection of the spring ligament, pie-crusting of the plantar fascia, and cyclic axial loading of the foot was performed to create an anatomic and functional flatfoot model. An Evans-type calcaneal osteotomy using 6, 8, 10, and 12 mm wedges was performed. Specimens were mounted to a custom jig that applies tensile loads to the Achilles, peroneus brevis, peroneus longus, and tibialis posterior tendons. Creation of a flatfoot reduced the lateral talo-first metatarsal angle (Meary's angle) by 13° (23.6° ± 2.8° vs 10.6° ± 3.8°, p < .05) and forefoot force by 7% (199.3 N ± 7.3 N vs 185.4 N ± 9 N, p < .05). Sequential lengthening of the lateral column restored skeletal alignment and force transfer to the forefoot (12 mm wedge: Meary's angle 22.7° ± 3.9°, liftoff force 206.8 N ± 7.5 N). The cadaveric flatfoot model demonstrated decreased forefoot forces that were restored with an Evans-type calcaneal osteotomy wedge. This highlights the importance of restoring skeletal alignment when correcting advanced adult acquired flatfoot.

Posterior Tibial Tendon Allograft Reconstruction for Stage II Adult Acquired Flatfoot: A Case Series

Surgical treatment for a stage II adult acquired flatfoot has consisted of reconstruction of the diseased posterior tibial tendon with flexor digitorum longus tendon transfer, combined with osteotomies to address the underlying deformity. This case series presents an alternative to tendon transfer using allograft tendon for posterior tibial tendon reconstruction. Four patients who underwent stage II flatfoot reconstruction with posterior tibial tendon allograft transplantation were included. All patients had preoperative radiographs demonstrating flatfoot deformity and magnetic resonance imaging showing advanced tendinopathy of the posterior tibial tendon. Allograft tendon transplant was considered in patients demonstrating adequate posterior tibial tendon excursion during intraoperative assessment. Additional procedures were performed as necessary depending on patient pathology. Postoperatively, all patients remained non-weightbearing in a short leg cast for 6 weeks. Radiographs performed during the postoperative course demonstrated well-maintained and improved alignment. No complications were encountered. Each patient demonstrated grade 5 muscle strength and were able to perform a single-limb heel rise at the time of final follow-up. The average follow-up duration was 19.0 months. Flexor digitorum longus transfer has been studied extensively for stage II adult acquired flatfoot. However, the flexor digitorum longus has been shown to be much weaker relative to the posterior tibial tendon, and concern remains regarding its ability to recreate the force of the posterior tibial tendon. Our results demonstrate that posterior tibial tendon allograft reconstruction combined with flatfoot reconstruction is a reasonable option. This alternative has the advantage of preserving the stronger muscle without disturbing regional anatomy.

Outcomes of the Extended Z-Cut Osteotomy for Correction of Adult Acquired Flatfoot Deformity

BACKGROUND

Medial displacement calcaneus tuberosity osteotomy and anterior process lengthening calcaneus osteotomy are traditional single-plane osteotomy techniques used in adult acquired flatfoot deformity reconstruction. More recently, 3-plane step-cut osteotomies were described for each of these and shown to offer improved rotational stability via the horizontal limb. However, a major technical challenge is achieving a sufficiently long horizontal limb to correct deformity through lengthening without losing bony apposition. Combining the anterior process and tuberosity step-cuts using an elongated horizontal limb alleviates this technical challenge, creates a very large surface area for bony healing, and utilizes a single incision. We hypothesized that the Z-cut osteotomy would achieve clinical and radiographic flatfoot deformity correction with a high union rate.

METHODS

This was an institutional review board-approved retrospective study of 16 patients who underwent Z-cut osteotomy for the treatment of moderate to severe symptomatic adult acquired flatfoot deformity, stage IIA/B. The mean radiographic follow-up was 8.8 months, while the mean clinical follow-up was 2.36 years. Radiographic correction was assessed via weightbearing radiographs taken preoperatively and at a mean of 26 ± 2 weeks postoperatively. Measurements included Meary's angle (talo-first metatarsal angle), talonavicular (TN) joint uncoverage percentage, TN incongruency angle, medial cuneiform to fifth metatarsal height, and calcaneal pitch. Union rates and clinical outcomes via the Foot Function Index (FFI) score were assessed preoperatively and at a mean of 29 months following surgery. Paired t test was used to compare both clinical and radiographic outcomes with statistical significance set at P < .05.

RESULTS

Fifteen of 16 patients returned an FFI questionnaire with a mean improvement of 52.1 to 10.3 (P = .002). The calcaneal pitch improved from 12.7 to 15.2 degrees (P = .002), the medial cuneiform-fifth metatarsal distance improved from 12.8 to 18.5 mm (P = .002), the TN coverage angle improved from 21.3 to 9.1 degrees (P < .001), the TN uncoverage percentage improved from 32.9% to 20.3% (P < .001), and the TN incongruency angle improved from 41.4 to 19.9 degrees (P < .001). Deformity correction was well maintained in 13 of 16 patients at final follow-up. The union rate of the osteotomy was 100%. Three patients had symptomatic hardware initially; 1 patient required removal of hardware. One patient developed a superficial infection that cleared. Another patient developed peroneal tendonitis, which resolved with corticosteroid injection.

CONCLUSION

The Z-cut osteotomy is a novel, technically simplified, single-incision, single-osteotomy alternative to the previously described double calcaneus osteotomy techniques for reconstructing flexible moderate to severe adult acquired flatfoot deformity that offers comparable short-term clinical and radiographic outcomes with acceptably low complications.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Repair of the Deltoid Ligament Using Posterior Tibial Tendon Autograft:A Novel Technique

Posterior tibial tendon dysfunction (PTTD) is a progressive disorder secondary to advanced degeneration of the posterior tibial tendon, leading to the abduction of the forefoot, valgus rotation of the hindfoot, and collapse of the medial longitudinal arch. Eventually, the disease becomes so advanced that it begins to affect the deltoid ligament over time. This attenuation and eventual tear of the deltoid ligament leads to valgus deformity of the ankle. Surgical correction of PTTD is performed to protect the ankle joint at all costs. Generally, this is performed using osteotomies of the calcaneus and repair or augmentation of the deltoid ligament. Unfortunately, there has been no universal procedure adapted by foot and ankle surgeons for repair or augmentation of the deltoid ligament. Articles have discussed the use of suture and suture anchors, suture tape, nonanatomic allograft repair, nonanatomic autograft repair with plantaris, peroneal and extensor halluces longus tendons to repair and augment the deltoid ligament. There is very little literature, however, in regard to using the posterior tibial tendon to augment the deltoid ligament in accordance with hindfoot fusion for end-stage PTTD deformity. In general, the posterior tibial tendon in triple and medial double arthrodesis is generally removed because it is thought to be a pain generator. This article presents a case study and novel technique using the posterior tibial tendon to augment and repair the laxity of the deltoid ligament in an advanced flatfoot deformity.

Subtalar Arthroereisis Implant Removal in Adults: A Prospective Study of 100 Patients

Subtalar joint arthroereisis (STA) can be used in the management of adult acquired flatfoot deformity (AAFD), including posterior tibial tendon dysfunction. The procedure is quick and normally causes little morbidity; however, the implant used for STA often needs to be removed because of sinus tarsi pain. The present study evaluated the rate and risk factors for removal of the implant used for STA in adults treated for AAFD/posterior tibial tendon dysfunction, including patient age, implant size, and the use of endoscopic gastrocnemius recession. Patients undergoing STA for adult acquired flatfoot were prospectively studied from 1996 to 2012. The inclusion criteria were an arthroereisis procedure for AAFD/posterior tibial tendon dysfunction, age >18 years, and a follow-up period of ≥2 years. The exclusion criteria were hindfoot arthritis, age <18 years, and a follow-up period of <2 years. A total of 100 patients (average age 53 years) underwent 104 STA procedures. The mean follow-up period was 6.5 (range 2 to 17) years. The overall incidence of implant removal was 22.1%. Patient age was not a risk factor for implant removal (p = .09). However, implant size was a factor for removal, with 11-mm implants removed significantly more frequently (p = .02). Endoscopic gastrocnemius recession did not exert any influence on the rate of implant removal (p = .19). After STA for AAFD, 22% of the implants were removed. No significant difference was found in the incidence of removal according to patient age or endoscopic gastrocnemius recession. However, a significant difference was found for implant size, with 11-mm implants explanted most frequently.

Imaging of adult flatfoot: correlation of radiographic measurements with MRI

OBJECTIVE. The purpose of this study is to determine whether radiographic foot measurements can predict injury of the posterior tibial tendon (PTT) and the supporting structures of the medial longitudinal arch as diagnosed on MRI. MATERIALS AND METHODS. After institutional review board approval, 100 consecutive patients with radiographic and MRI examinations performed within a 2-month period were enrolled. Thirty-one patients had PTT dysfunction clinically, and 69 patients had other causes of ankle pain. Talonavicular uncoverage angle, incongruency angle, calcaneal pitch angle, Meary angle, cuneiform-to-fifth metatarsal height, and talar tilt were calculated on standing foot or ankle radiographs. MRI was used to assess for abnormalities of the PTT (tenosynovitis, tendinosis, and tear) and supporting structures of the medial longitudinal arch (spring ligament, deltoid ligament, and sinus tarsi). Statistical analysis was performed using the chi-square and Fisher exact tests for categoric variables; the Student t test was used for continuous variables. RESULTS. There was a statistically significant association of PTT tear with abnormal talonavicular uncoverage angle, calcaneal pitch angle, Meary angle, and cuneiform-to-fifth metatarsal height. PTT tendinosis and isolated tenosynovitis had a poor association with most radiologic measurements. If both calcaneal pitch and Meary angles were normal, no PTT tear was present. An abnormal calcaneal pitch angle had the best association with injury to the supporting medial longitudinal arch structures. CONCLUSION. Radiographic measurements, especially calcaneal pitch and Meary angles, can be useful in detecting PTT tears. Calcaneal pitch angle provides the best assessment of injury to the supporting structures of the medial longitudinal arch.

Posterior tibial tendon insufficiency results at different stages

The results of surgical treatment of posterior tibial tendon insufficiency (PTTI) may be different at different stages of the disease. No single study has compared the results at different stages. This comparison can be helpful to the patient and physician if the patient asks "What if I wait and the disease progresses, how will my results be different?" A preliminary study comparing results for stage IIa, stage IIb (advanced stage II), and stage III was performed followed by a larger study comparing IIa and IIb with 26 and 22 patients, respectively. American Orthopaedic Foot and Ankle Society (AOFAS) outcome scores as well as radiographs and functional questions were used. Nearly all patients, regardless of stage, felt they were helped by surgical treatment. However, the lowest AOFAS score was in stage III, the most advanced stage investigated in this study. In comparing stage IIa and IIb patients, stage IIb patients had a statistically higher incidence of lateral discomfort. Although statistically significant differences were not found in all comparisons, this study suggests that the results of surgical treatment for PTTI declines with increasing stage or severity of disease.