Finite Element Modeling of Planus and Rectus Foot Types for the Study of First Metatarsophalangeal and First Metatarsocuneiform Joint Contact Mechanics.

The foot is a highly complex biomechanical system for which finite element (FE) modeling has been used to evaluate its loading environment. However, there is limited knowledge of first metatarsophalangeal (MTP) and first metatarsocuneiform (MTC) joint contact mechanics. Our goal was to develop a framework for FE modeling of the medial forefoot which could accurately predict experimental measurements of first MTP and first MTC joint loading. Simulations of planus and rectus foot types were conducted for midstance of gait. A custom-built force-controlled cadaveric test-rig was used to derive intracapsular pressure sensor measurements of contact pressure, force, and area during quasi-static loading. The FE model was driven under the same boundary and loading conditions as the cadaver. Mesh sensitivity analyses and best-fit calibrations of moduli for first MTP and first MTC joint cartilage were performed. Consistent with previous experimental research, a lower compressive modulus was best-fit to the first MTP compared to first MTC joint at 10 MPa and 20 MPa, respectively. Mean errors in contact pressures, forces, and areas were 24%, 4%, and 40% at the first MTP joint and 23%, 12%, and 19% at the first MTC joint, respectively. The present developmental framework may provide a basis for future modeling of first MTP and first MTC joint contact mechanics. This study acts as a precursor to validation of realistic physiological loading across gait to investigate joint loading, foot type biomechanics, and surgical interventions of the medial forefoot.

Accuracy of patient-specific instrumentation in total ankle arthroplasty: A comparative study.

BACKGROUND: Patient-specific instrumentation (PSI) for TAA is a novel technology with several potential benefits. The primary goal of this study was to compare the use of PSI with the standard referencing guide (SRG) in regards to accuracy of tibial implant positioning. Operative time, fluoroscopy time and accuracy of PSI preoperative reports were also evaluated. METHODS: A retrospective analysis of 99 patients who underwent a primary TAA with the INFINITY prosthesis (Wright Medical, Memphis, TN) was performed. Patients were divided in two groups based on the type of instrumentation used during the TAA (75 in the PSI group vs 24 in the SRG group). There was no significant difference between groups in regards to age at the time of surgery (P=0.122), sex (P=0.138), number of concomitant procedures performed during surgery (P=0.567) and etiology (P=0.841). However, preoperative deformity was significantly smaller in the PSI group (P=0.002). RESULTS: Tibial implant positioning was similar between groups. In the coronal plane, the absolute deviation of the tibial implant from the intended alignment was 1.7±1.4° for the SRG and 1.6±1.2° for PSI (P=0.710). In the sagittal plane, the absolute alignment deviation of the tibial implant was 1.8±1.4° for the SRG and 1.9±1.5° for PSI (P=0.675). Operative time (167 vs 190min, P=0.040) and fluoroscopy time (85 vs 158s, P<0.001) were significantly decreased in the PSI group. The PSI preoperative plan report correctly predicted the implant size in 73% of cases for the tibial component and in 51% of cases for the talar component. CONCLUSIONS: PSI provided similar tibial component alignment as standard instrumentation. Additionally, PSI preoperative plan reports were poor predictors of implant sizing. Therefore, the final decision should always be based on surgeon's experience in order to prevent errors in implant sizing and positioning. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Passive Eversion Assessment for Progressive Collapsing Foot Deformity After Lateral Column Lengthening: A Cadaveric Biomechanical Study.

BACKGROUND: Reduced hindfoot eversion motion has been proposed as a cause of increased lateral foot pressure following lateral column lengthening (LCL) for progressive collapsing foot deformity (PCFD). A subjective intraoperative assessment of passive eversion has been suggested to help evaluate correction; however, it is unclear how passive eversion correlates with objective measurements of foot stiffness. Our objectives were to quantify the relationship between the maximum passive eversion in hindfoot joints following LCL with plantar pressure during stance and to determine the influence of wedge size on these outcomes. METHODS: Ten cadaveric specimens extending from the mid-tibia distally were tested on a 6-degrees-of-freedom robot to simulate the stance phase of level walking. Five conditions were tested: intact, simulated PCFD, and 3 LCL wedge conditions (4, 6, and 8 mm). Outcomes included the lateral-to-medial forefoot plantar pressure (LM) ratio during stance and the maximum passive eversion measured in the hindfoot joints. Simple linear regressions were performed to evaluate relationships between outcomes and wedge sizes. RESULTS: A strong negative relationship was found between passive subtalar eversion and the LM ratio during stance (r[38] = -0.46; p = 0.0007), but not between passive talonavicular eversion and the LM ratio (r[38] = -0.02; p = 0.37). Wedge size was strongly related to subtalar eversion (r[38] = -0.77; p < 0.0001), talonavicular eversion (r[38] = -0.55; p = 0.0003), and the LM ratio (r[38] = 0.70; p < 0.0001). Increased wedge size resulted in average decreases in subtalar and talonavicular eversion of 1.0° (95% confidence interval [CI]: 0.8° to 1.3°) and 1.2° (95% CI: 0.6° to 1.6°), respectively. Increased wedge size also increased the LM ratio by 0.38 (95% CI: 0.25 to 0.50), indicating a lateral shift in plantar pressure. CONCLUSIONS: Decreased hindfoot eversion following LCL was related to increased lateral plantar pressure during stance. Increasing wedge size correlated with decreasing passive hindfoot eversion and increasing lateral plantar pressure, suggesting that intraoperative preservation of eversion motion may be important for preventing excessive lateral loading. CLINICAL RELEVANCE: To avoid overcorrection or undercorrection of the deformity, hindfoot eversion assessment in addition to radiographic evaluation may be important for optimizing the amount of lengthening to achieve successful LCL.

A Patient-Reported Outcome-Based Comparison of Cheilectomy With and Without Proximal Phalangeal Dorsiflexion Osteotomy for Hallux Rigidus.

INTRODUCTION: This study provides the first comparison of patient-reported outcomes between isolated cheilectomy (C) and cheilectomy with Moberg (CM) osteotomy for hallux rigidus. METHODS: A single-center, retrospective registry search identified all patients with preoperative Patient-Reported Outcomes Measurement Information System (PROMIS) scores who underwent cheilectomy, with and without concomitant proximal phalangeal dorsiflexion osteotomy, for hallux rigidus between January 2016 and December 2020. Because there were far fewer isolated cheilectomies (62), all C patients were compared with a commensurate number of consecutive CM cases (67) using preoperative, 1-year, and 2-year PROMIS scores for physical function, pain interference, pain intensity, global physical health, global mental health, and depression, as well as complication and revision data from a chart review. A multivariable linear regression analysis was performed to compare adjusted postoperative PROMIS scores between the 2 cohorts. RESULTS: There were no differences between groups among the demographic and preoperative variables compared. The CM cohort reported worse pain interference scores preoperatively (P < .001) and at 1 year postoperatively (P = .01). However, the C cohort reported worse pain intensity scores preoperatively (P < .001) and at 1 year postoperatively (P < .001). Adjusted postoperative PROMIS score comparison demonstrated that the CM cohort had better 1-year postoperative pain intensity scores (P < .05). However, there were no differences between cohorts for additional PROMIS scores or complications data. CONCLUSION: The addition of a Moberg osteotomy does not appear to significantly change short- to medium-term outcomes of cheilectomy for hallux rigidus treatment. LEVELS OF EVIDENCE: Level III: Retrospective comparative study.

Peroneus Brevis to Longus Tendon Transfer in the Treatment of Flexible Progressive Collapsing Foot Deformity: A Cadaveric Study.

BACKGROUND: Although operative treatment of the flexible progressive collapsing foot deformity (PCFD) remains controversial, correction of residual forefoot varus and stabilization of the medial column are important components of reconstruction. A peroneus brevis (PB) to peroneus longus (PL) tendon transfer has been proposed to address these deformities. The aim of our study was to determine the effect of an isolated PB-to-PL transfer on medial column kinematics and plantar pressures in a simulated PCFD (sPCFD) cadaveric model. METHODS: The stance phase of level walking was simulated in 10 midtibia cadaveric specimens using a validated 6-degree of freedom robot. Bone motions and plantar pressure were collected in 3 conditions: intact, sPCFD, and after PB-to-PL transfer. The PB-to-PL transfer was performed by transecting the PB and advancing the proximal stump 1 cm into the PL. Outcome measures included the change in joint rotation of the talonavicular, first naviculocuneiform, and first tarsometatarsal joints between conditions. Plantar pressure outcome measures included the maximum force, peak pressure under the first metatarsal, and the lateral-to-medial forefoot average pressure ratio. RESULTS: Compared to the sPCFD condition, the PB-to-PL transfer resulted in significant increases in talonavicular plantarflexion and adduction of 68% and 72%, respectively, during simulated late stance phase. Talonavicular eversion also decreased in simulated late stance by 53%. Relative to the sPCFD condition, the PB-to-PL transfer also resulted in a 17% increase (P = .045) in maximum force and a 45-kPa increase (P = .038) in peak pressure under the first metatarsal, along with a medial shift in forefoot pressure. CONCLUSION: The results from this cadaver-based simulation suggest that the addition of a PB-to-PL transfer as part of the surgical management of the flexible PCFD may aid in correction of deformity and increase the plantarflexion force under the first metatarsal. CLINICAL RELEVANCE: This study provides biomechanical evidence to support the addition of a PB-to-PL tendon transfer in the surgical treatment of flexible PCFD.

Influence of Isolated Talonavicular and Subtalar Joint Arthrodesis on Hindfoot Kinematics and Range of Motion During Cadaveric Gait Simulation.

BACKGROUND: Isolated subtalar and talonavicular joint arthrodeses have been associated with adjacent joint arthritis and altered hindfoot kinematics during simplified loading scenarios. However, the effect on kinematics during dynamic activity is unknown. This study assessed changes in subtalar and talonavicular kinematics after isolated talonavicular (TNiso) and subtalar (STiso) arthrodesis, respectively, during stance simulations. METHODS: Fourteen midtibia specimens received either a TNiso or STiso arthrodesis, with 7 randomized to each group. A 6-degree-of-freedom robot sequentially simulated the stance phase for the intact and arthrodesis conditions. Bootstrapped bias-corrected 95% CIs of the talonavicular and subtalar joint kinematics were calculated and compared between conditions. RESULTS: The TNiso decreased subtalar inversion, adduction, and plantarflexion in late stance (P < .05). The subtalar range of motion in the sagittal and coronal planes decreased by 40% (P = .009) and 46% (P = .002), respectively. No significant changes in talonavicular joint kinematics were observed after isolated subtalar arthrodesis; however, the range of motion was reduced by 61% (P = .007) and 50% (P = .003) in the coronal and axial planes, respectively. CONCLUSION: In this model for arthrodesis, changes in subtalar kinematics and motion restriction were observed after isolated talonavicular arthrodesis, and motion restriction was observed after isolated subtalar arthrodesis. Surprisingly, talonavicular kinematics did not appear to change after isolated subtalar arthrodesis. CLINICAL RELEVANCE: Both joint fusions substantially decrease the motion of the reciprocal adjacent joint. Surgeons should be aware that the collateral costs with talonavicular fusion appear higher, and it has a significant effect on subtalar kinematics during the toe-off phase of gait.

Correction of multiplanar deformity of the second toe with metatarsophalangeal release and extensor brevis reconstruction.

BACKGROUND: Surgical treatment of multiplanar (varus and dorsal angulation) second toe deformities due to degenerative instability can lead to recurrence, stiffness, and pain. The goal of this study was to evaluate the short-term outcomes associated with a new technique using an extensor digitorum brevis (EDB) tendon reconstruction to correct such deviation of the second metatarsophalangeal (MTP) joint. METHODS: Ten patients (10 female, 0 male) with 11 operated second toes having undergone correction with a reconstruction using the EDB tendon were assessed at an average of 18.5 months (range, 12-34) after surgery. The technique was indicated when MTP and medial partial plantar plate release alone were not sufficient to correct multiplanar deformity. Radiographic parameters (AP and lateral metatarsal-proximal phalanx angles), physical exam (MTP joint range of motion), and subjective outcomes (the Foot and Ankle Outcome Score [FAOS]) were assessed. A toe-specific survey captured more detailed subjective information, including patient satisfaction. RESULTS: Preoperatively, the average MTP joint angle was 4.5 degrees in the varus direction, which changed to 14.2 degrees in the valgus direction postoperatively. On exam, the average MTP joint range of motion was 60.9 ± 11.6 degrees dorsiflexion and 11.1 ± 2.5 degrees plantarflexion. Postoperative FAOS scores demonstrated an average of 89.9 ± 9.8 for the symptoms domain. In all, 9 of 11 patients were either highly satisfied or moderately satisfied (none dissatisfied). CONCLUSION: With the stated limitations, the EDB tendon reconstruction technique described in conjunction with collateral ligament and partial plantar plate release provided powerful correction. Minimal release of the medial plantar plate and not overtightening the reconstruction are recommended to avoid shifting the toe in the opposite direction. LEVEL OF EVIDENCE: Level IV, retrospective study.

Costs and benefits of routine histopathological examination of hammertoe specimens.

BACKGROUND: The purpose of this study was to evaluate the cost and benefit of routinely submitting hammertoe specimens for histopathological examination. We hypothesized that such examination rarely shows a new diagnosis and seldom alters postoperative care. MATERIALS AND METHODS: Three hundred and fourteen proximal interphalangeal (PIP) joint and 37 extensor tendon specimens from 187 consecutive hammertoe correction surgeries were submitted by 2 surgeons for histopathological examination between January 2009 and December 2011. Each patient's chart was reviewed to determine whether the histopathological examination revealed a diagnosis other than degenerative joint or degenerative tendon and whether subsequent patient management was altered. The total reimbursements for professional charges were calculated using the average reimbursement from common insurance providers for two Current Procedural Terminology (CPT) codes: 88304 (soft tissue examination) and 88311 (decalcification). RESULTS: Almost all of the specimens were diagnosed as degenerative: 97.5% (307/314) of the PIP specimens and all (37/37) of the tendon specimens. Seven PIP specimens (2.2%, 7/314) from 5 patients (2.7%, 5/187) and no tendon specimens had other diagnoses. These diagnoses were rheumatoid arthritis (5/314, 1.6%), osteomyelitis (1/314, 0.3%), and pigmented villonodular synovitis (PVNS) (1/314, 0.3%). Only the PVNS was a new diagnosis. A total of $56,750 was spent to determine 1 new diagnosis. CONCLUSION: The routine submission of hammertoe specimens for pathological evaluation was not cost-efficient. Our analysis showed that new diagnoses were rarely found and patient management was not affected.

The contribution of medializing calcaneal osteotomy on hindfoot alignment in the reconstruction of the stage II adult acquired flatfoot deformity.

BACKGROUND: Successful correction of hindfoot alignment in adult acquired flatfoot deformity (AAFD) is likely influenced by the degree of medializing calcaneal osteotomy (MCO) performed, but it is not known if other reconstruction procedures significantly contribute as well. The purpose of this study was to evaluate the correlation between common preoperative and postoperative variables and hindfoot alignment. METHODS: Thirty patients with stage II AAFD undergoing flatfoot reconstruction were followed prospectively. Preoperative and postoperative radiographs were reviewed to assess for correction in hindfoot alignment as measured by the change in hindfoot moment arm. Nineteen variables were analyzed, including age, gender, height, weight, body mass index (BMI), medial cuneiform-fifth metatarsal height, anteroposterior (AP) talonavicular coverage, AP talus-first metatarsal, lateral talus-first metatarsal and calcaneal pitch angles as well as intraoperative use of the MCO, lateral column lengthening (LCL), Cotton osteotomy, first tarsometatarsal fusion, flexor digitorum longus transfer, spring ligament reconstruction, and gastrocnemius recession or Achilles lengthening. Mean age was 57.3 years (range, 22-77). Final radiographs were obtained at a mean of 47 weeks (range, 25-78) postoperatively. RESULTS: Seven variables were found to significantly affect hindfoot moment arm. These were gender (P < .05), the amount of MCO performed (P < .001), LCL (P < .01), first tarsometatarsal fusion (P < .01), spring ligament reconstruction (P < .01), medial cuneiform-fifth metatarsal height (P < .001), and calcaneal pitch angle (P < .05). Multivariate regression analysis revealed that MCO was the only significant predictor of hindfoot moment arm. The final regression model for MCO showed a good fit (R(2) = .93, P < .001). CONCLUSION: Correction of hindfoot valgus alignment obtained in flatfoot reconstruction is primarily determined by the MCO procedure and can be modeled linearly. We believe that the hindfoot alignment view can serve as a valuable preoperative measurement to help surgeons adjust the proper amount of correction intraoperatively. LEVEL OF EVIDENCE: Level IV, prospective case series.

Validation of the Foot and Ankle Outcome Score in adult acquired flatfoot deformity.

INTRODUCTION: The American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Score has been under recent scrutiny. The Foot and Ankle Outcome Score (FAOS) is an alternative subjective survey, assessing outcomes in 5 subscales. It is validated for lateral ankle instability and hallux valgus patients. The aim of our study was to validate the FAOS for assessing outcomes in flexible adult acquired flatfoot deformity (AAFD). METHODS: Patients from the authors' institution diagnosed with flexible AAFD from 2006 to 2011 were eligible for the study. In all, 126 patients who completed the FAOS and the Short-Form 12 (SF-12) on the same visit were included in the construct validity component. Correlation was deemed moderate if the Spearman's correlation coefficient was .4 to .7. Content validity was assessed in 63 patients by a questionnaire that asked patients to rate the relevance of each FAOS question, with a score of 2 or greater considered acceptable. Reliability was measured using intraclass correlation coefficients (ICCs) in 41 patients who completed a second FAOS survey. In 49 patients, preoperative and postoperative FAOS scores were compared to determine responsiveness. RESULTS: All of the FAOS subscales demonstrated moderate correlation with 2 physical health related SF-12 domains. Mental health related domains showed poor correlation. Content validity was high for the Quality of Life (QoL; mean 2.26) and Sports/Recreation subscales (mean 2.12). All subscales exhibited very good test-retest reliability, with ICCs of .7 and above. Symptoms, QoL, pain, and daily activities (ADLs) were responsive to change in postoperative patients (P < .05). CONCLUSION: This study has validated the FAOS for AAFD with acceptable construct and content validity, reliability, and responsiveness. Given its previous validation for patients with ankle instability and hallux valgus, the additional findings in this study support its use as an alternative to less reliable outcome surveys. LEVEL OF EVIDENCE: Level II, prospective comparative study.

Achilles tendon rupture in women.

BACKGROUND: The incidence of Achilles rupture appears to be less in women, although this notion has not been specifically investigated in the literature. METHODS: The medical records of 7 foot-and-ankle orthopaedic surgeons at 1 institution were reviewed by Current Procedural Terminology (code 27650) and International Classification of Diseases-9 (code 727.67) to establish all Achilles tendon ruptures seen and/or treated by these surgeons. Sex, age, side, and mechanism of injury were recorded. Whether the patient had an acute Achilles tendon rupture or nonacute Achilles pathology was also noted. RESULTS: A total of 468 patients were identified, of whom 358 had acute ruptures: 302 male and 56 female (5.39:1). Patients with acute ruptures were significantly younger than those with nonacute pathology (43.8 vs 55.1, P < .001). For acute ruptures, the mean age was not significantly different between men and women (43.9 vs 43.2; P = .780). Athletic activity was causative in 243 of 302 men (80.5%) and in 40 of 56 women (71.4%). This difference was not statistically significant (P = .130). Six men (2.0%) and 6 women (10.7%) had comorbidities that were thought to increase their risk of rupture (P = .005). CONCLUSION: Achilles tendon rupture is more common in men than women. Previous studies using the aforementioned codes to identify patients without chart review may have overestimated the number of women with acute Achilles tendon rupture. LEVEL OF EVIDENCE: Level III, retrospective comparative series.

Medium- to Long-term Results of Nonanatomic Spring Ligament Reconstruction Using an Allograft Tendon in Progressive Collapsing Foot Deformity With Severe Abduction Deformity.

BACKGROUND: Spring ligament reconstruction (SLR) has been suggested as an adjunct to other reconstructive procedures to potentially avoid talonavicular joint fusion in progressive collapsing foot deformity (PCFD) with severe abduction deformity. Most clinical reports present short-term follow-up data and a small number of patients. The purpose of this study was to examine the medium- to long-term outcomes of an SLR using allograft tendon augmentation as part of PCFD surgical reconstruction. This study to our knowledge represents the largest number of patients and the longest follow-up to date. METHODS: This study retrospectively reviewed 26 patients (27 feet, mean age of 61.4 years) who underwent SLR with allograft tendon as part of PCFD reconstruction. The mean follow-up of the cohort was 8 years (range, 5-13.4). Radiographic evaluation consisted of 5 parameters including talonavicular coverage angle (TNC), with the maintenance of correction being evaluated by comparing parameters from the early postoperative period (mean: 11.6 months, range, 8-17) to final follow-up. Foot and Ankle Outcome Score (FAOS) and patient satisfaction questionnaires were collected at final follow-up. Conversion to talonavicular or subtalar fusion was considered as a failure. RESULTS: Final radiographs demonstrated successful abduction correction, with the mean TNC improving from 43.7 degrees preoperatively to 14.1 degrees postoperatively (P < .0001). All other radiographic parameters improved significantly and exhibited maintenance of the correction. All FAOS subscales showed significant improvement. Responses to the satisfaction questionnaire were received from all except 1 patient, of whom 88.5% (23/26) were satisfied with the results, 96.2% (25/26) would undergo the surgery again, and 88.5% (23/26) would recommend the surgery. Eight feet (29.6%) required painful hardware removal and 1 (3.7%) developed nonunion of the lateral column lengthening osteotomy. No patient required conversion to talonavicular or subtalar fusion. CONCLUSION: This study demonstrates favorable medium- to long-term outcomes following PCFD reconstruction including an SLR with allograft tendon augmentation. LEVEL OF EVIDENCE: Level IV, case series.

Clinical Outcomes of the Lateral Trabecular Metal Total Ankle Replacement at a 5-Year Minimum Follow-up.

BACKGROUND: The Trabecular Metal (Zimmer Biomet, Warsaw, IN) total ankle arthroplasty (TAA) system uses a lateral approach with a fibular osteotomy to gain access to the tibiotalar joint and a sagittally curved tibial component. This is the first TAA system to laterally approach the ankle, and few studies have explored outcomes associated with this implant. This study aimed to report the 5-year clinical and radiographic outcomes as well as the survivorship of the implant. METHODS: Over a 3-year period, 2 fellowship-trained foot and ankle surgeons used this implant system to treat 38 end-stage arthritic ankles. Reoperation and revision data were collected from all patients (100%) as part of the local prospective database. Patients completed the Foot and Ankle Outcome Score (FAOS) questionnaire preoperatively and at each annual follow-up visit; scores for a minimum of 5 years were available for 28 (73.7%) patients. A radiographic analysis compared postoperative coronal and sagittal alignment in weightbearing radiographs at a minimum of 5 years with that at 3 months postoperatively, as well as cyst or lucency formation, which was available for 21 patients (55.3%). RESULTS: At 5 years, there were 3 revisions (7.9%) and 9 reoperations (23.7%). Reoperations included 4 fibular hardware removal and 5 medial gutter debridement procedures. The FAOS significantly improved for all domains (P < .05). Implant positioning did not significantly change between 3 months and 5 years postoperatively. CONCLUSION: Our 5-year results in this small series using this unique prosthesis showed good overall survivorship (92.1%) and a reoperation rate of 23.7%, along with clinically significant improvement in patient-reported outcomes. LEVELS OF EVIDENCE: Level IV: Retrospective case series.

Midterm Clinical Outcomes, Radiographic Outcomes, and Survivorship of the Infinity Total Ankle Arthroplasty.

BACKGROUND: The Infinity Total Ankle Arthroplasty (Stryker, Mahwah, NJ) is a low-profile fixed-bearing implant first introduced in 2014. Although the short-term survivorship (2-4 years follow-up) and complication rates of the Infinity TAA have been reported, there are limited midterm outcome reports. The aim of this study was to describe the survivorship and clinical outcomes of a single-center experience with the Infinity implant at minimum 5-year follow-up. METHODS: Retrospective review of 65 ankles that underwent primary total ankle arthroplasty (TAA) with the Infinity implant was conducted. Mean clinical follow-up was 6.5 years (range, 5.0-8.0). Preoperative and postoperative radiographs were measured to assess tibiotalar alignment, periprosthetic lucencies, and cysts. Preoperative, 2-year, and 5-year postoperative Foot and Ankle Outcome Score (FAOS) subscores were compared to assess midterm clinical outcomes. Survivorship assessment was determined by removal of 1 or both metallic implant components. RESULTS: Survivorship of the implant was 93.8% at final follow-up. There were 4 revisions: 2 for tibial implant loosening, 1 for talar loosening, and 1 for loosening of both components. Three of the 4 revisions occurred within the first 2 years following implantation, and the last failure occurred at 7 years postoperatively. There were 11 reoperations in 10 (15%) ankles and 3 wound complications. There were 17 ankles (26.2%) with radiographic abnormalities around the implants, including 14 cases with tibial component lucencies and 4 cases of periimplant cysts. FAOS outcome measurement showed general stability between 2 and 5 years and substantial improvement from preoperative status. CONCLUSION: To date this study is the largest midterm report on the Infinity total ankle prosthesis, with 65 implants at a mean follow-up of 6.5 years. We found good midterm implant survivorship, and patients experienced significant improvements in FAOS outcome scores and radiographic alignment at final follow-up. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Midterm outcome of modified Kidner procedure.

BACKGROUND: The results of modified Kidner procedures have generally been satisfactory at short-term followup. The objective of this study was to evaluate the midterm followup results including medial longitudinal arch height. METHODS: Forty-one patients (50 feet) with a symptomatic accessory navicular who underwent the modified Kidner procedure between July 1999 and February 2004 were evaluated. A midfoot AOFAS score, VAS score, and satisfaction rate were recorded. The talo-first metatarsal (T-MT1), talo-calcaneal (TC), and calcaneal pitch (CP) angles were measured on plain radiographs. Average clinical and radiological followup periods were 88.4 ±17.0 months and 85.7 ±15.0 months, respectively. RESULTS: The mean preoperative and followup AOFAS scores were 40.8 ±7.1 (range, 32 to 57), and 88.4 ±7.9 (range, 72 to 100), respectively (p < 0.01). The mean preoperative and followup VAS scores were 7.1 ±1.0 (range, 4 to 9) and 1.8 ±1.0 (range, 0 to 5), respectively (p < 0.01). At last followup , the satisfaction rate was 82.0%. There were no significant differences between preoperative and followup T-MT1 (p = 1.00), TC (p = 0.84), and CP (p = 0.08) angles. Increased medial longitudinal arch was found in four of 16 feet in patients 15 years of age or younger with followup radiographs. CONCLUSION: We found the modified Kidner procedure could result in symptomatic relief and high satisfaction rate without a loss of arch height in any patient.

Validation of foot and ankle outcome score for hallux valgus.

BACKGROUND: Patient-reported outcome questionnaires such as the Foot and Ankle Outcome Score (FAOS) are useful in evaluating results after orthopedic interventions. However, despite being frequently used in the literature, its validity has not been established for forefoot disorders. Our study aimed to validate the FAOS for use in assessing outcomes of hallux valgus surgery. METHODS: From 2006 to 2009, 195 patients with nonarthritic hallux valgus were included in the construct validity portion of the study. Patients had a SF-36 and a FAOS completed. Forty additional patients, both preoperative and postoperative, were given questionnaires to assess the relevance of each of the FAOS questions as it pertained to their bunions. Patients were also given the FAOS 1 month after the first to assess FAOS reliability. Responsiveness of the FAOS was included with 40 patients who had both preoperative and postoperative FAOS scores. RESULTS: Four out of five FAOS subscales demonstrated acceptable correlation with the SF-36. The FAOS symptoms subscale showed the least correlation with SF-36, demonstrating the foot-specific nature of the questions. Both preoperative and postoperative patients rated the FAOS quality of life questions as the most relevant. All five subscales achieved acceptable test-retest reliability. The FAOS sports and recreation subscale was the least responsive. CONCLUSION: Patient-based assessments have become increasingly important in evaluating treatment effectiveness. This study has shown that the FAOS has acceptable construct validity, reliability, and responsiveness in hallux valgus patients and is a useful patient-based tool in assessing these patients.

Assessment of Flatfoot Deformity Using Digitally Reconstructed Radiographs: Reliability and Comparison to Conventional Radiographs.

BACKGROUND: Digitally reconstructed radiographs (DRRs) generated from weightbearing computed tomography (WBCT) may potentially substitute for weightbearing plain radiographs (XRs) but have not been clinically validated. This study aims to test the reliability of 6 radiographic parameters of progressive collapsing foot deformity (PCFD) as measured on DRR, to investigate whether DRR represents comparably to XR through the same measurements, and to compare agreement of DRR and XR measurements of a standardized arch height parameter with reference measurements made on WBCT. METHODS: DRR generated from preoperative WBCT of 71 patients (72 feet) treated surgically for PCFD were retrospectively compared with preoperative weight-bearing XR after exclusion criteria were applied. Six radiographic measurements were performed, including Meary angle, calcaneal pitch (CPA), medial cuneiform height (MCH), AP talar-first metatarsal angle (T-1MT), talonavicular coverage (TNCA), and talar incongruency (TIA). Arch height was measured on XR, DRR, and WBCT using a validated, standardized, navicular-based index. Intraclass correlation coefficients assessed DRR intraobserver and interobserver reliability. Paired samples t tests tested differences between XR and DRR. Bland-Altman limits of agreement analysis compared DRR and XR agreement with WBCT measurements. RESULTS: Measurements were within standard PCFD ranges on XR and DRR. All measurements demonstrated excellent intrarater reliability and good to excellent interrater agreement, consistent with previous literature on XR. No differences were found for Meary, CPA, or TNCA. Minor differences were observed for MCH, T-1MT, and TIA. DRR measurements demonstrated greater agreement with WBCT than XR measurements. CONCLUSION: DRR from WBCT may be a promising substitute for XR in the clinical evaluation of PCFD. Radiographic measurements made on DRR demonstrated good to excellent reliability. Although small differences were found between XR and DRR for certain measurements, DRR more accurately represented medial arch anatomy compared to gold standard WBCT data than XR. If validated as a clinical substitute, DRR could eventually obviate XR where WBCT is available. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Is the Planus Foot Type Associated With First Ray Hypermobility?

Background: Many foot pathologies have been associated with foot type. However, the association of first ray hypermobility remains enigmatic. The purpose of this study was to investigate first ray hypermobility among participants with planus and rectus foot types and its influence on static measures of foot structure. Methods: Twenty asymptomatic participants with planus (n = 23 feet) and rectus (n = 17 feet) foot types were enrolled. Several parameters of static foot structure (arch height index, arch height flexibility, first metatarsophalangeal joint flexibility, and first ray mobility) were measured. Participants were further stratified into groups with nonhypermobile (n = 26 feet) and hypermobile (n = 14 feet) first rays. First ray mobility ≥8 mm was used to define "first ray hypermobility". Generalized estimating equations, best-fit regression lines, and stepwise linear regression were used to identify significant differences and predictors between the study variables. Results: Overall, 86% of subjects categorized with first ray hypermobility exhibited a planus foot type. Arch height flexibility, weightbearing first ray mobility, and first metatarsophalangeal joint flexibility showed no significant between-group differences. However, weightbearing ray mobility and first metatarsophalangeal joint laxity were associated with partial weightbearing first ray mobility, accounting for 38% of the model variance. Conclusion: The planus foot type was found to be associated with first ray hypermobility. Furthermore, weightbearing first ray mobility and first metatarsophalangeal joint laxity were predictive of partial weightbearing first ray mobility, demonstrating an interaction between the translation and rotational mechanics of the first ray. Clinical Relevance: Association of first ray hypermobility with foot type and first metatarsophalangeal joint flexibility may help understand the sequela to symptomatic pathologies of the foot.

Return to Physical Activity Following Flatfoot Reconstruction.

BACKGROUND: Progressive collapsing foot deformity (PCFD) is a debilitating condition encompassing several interrelated, progressive deformities requiring a combination of reconstructive procedures. Few studies investigate returns to activity following flatfoot reconstruction, and existing studies only examine 1 or 2 of the numerous procedures employed. This study aims to provide the first generalizable assessment of returns to sports and physical activity following reconstruction surgery in patients with flexible flatfoot deformity. METHODS: Patients aged 18-60 years who underwent reconstructive surgery between February 16 and May 19 for symptomatic flexible-stage flatfoot deformity were identified by registry review. Eighty-two of 113 eligible patients (73%) were reached at a mean 2.9 years (range, 2.0-5.4) of follow-up with mean age at surgery of 48.9 years (range, 18-59). Returns to physical activity were evaluated with a sports-specific survey. Clinical outcomes were evaluated with Patient-Reported Outcomes Measurement Information System (PROMIS) scores. RESULTS: Patients reported participation in 21 specific sports and activities. One-fourth (25.6%) of patients (21/82) reported increased difficulty with physical activities postoperatively, 15.9% reported equal difficulty, and 58.5% (48/82) reported decreased difficulty. Median return times were 9-12 months for participation and 12-18 months to reach maximum preoperative participation levels. Improvements in Physical Function (P= .001), Pain Interference (P < .001), Pain Intensity (P <.001), and Global Physical Health (P = .004) were associated with increased satisfaction with respect to sports and physical activities. DISCUSSION: This study investigated participation in specific sports and physical activities following flatfoot reconstruction. Our findings suggest mixed outcomes, where many patients reported life-changing improvements but many also experienced prolonged pain and difficulty after surgery. Some patients reported increased difficulty or inability to return to their preoperative maximum level of participation, indicating that flatfoot reconstructions can lead to athletic limitations. CONCLUSION: Although flatfoot reconstruction can be a powerful tool to increase patients' capacity to engage in physical activity, in our cohort many patients had reduced physical activity outcomes. LEVEL OF EVIDENCE: Level IV, retrospective case series.