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Ankle osteoarthritis does not only led to lower ankle power generation, but also results in compensatory gait mechanics at the hip and Chopart joints. Much of previous work explored the relative work distribution after total ankle replacement (TAR) either across the lower extremity joints where the foot was modelled as a single rigid unit or across the intrinsic foot joints without considering the more proximal lower limb joints. Therefore, this study aims, for the first time, to combine 3D kinetic lower limb and foot models together to assess changes in the relative joint work distribution across the foot and lower limb joints during level walking before and after patients undergo TAR. We included both patients and healthy control subjects. All patients underwent a three-dimensional gait analysis before and after surgery. Kinetic lower limb and multi-segment foot models were used to quantify all inter-segmental joint works and their relative contributions to the total lower limb work. Patients demonstrated a significant increase in the relative ankle positive joint work contribution and a significant decrease in the relative Chopart positive joint work contribution after TAR. Furthermore, there exists a large effect toward decreases in the relative contribution of the hip negative joint work after TAR. In conclusion, this study seems to corroborate the theoretical rationale that TAR reduces the compensatory strategy in the Chopart and hip joints in patients suffering from end-stage ankle osteoarthritis.

Abstract Background This study evaluated the 3D angle between the joint moment and the joint angular velocity vectors at the intrinsic foot joints, and investigated if these joints are predominantly driven or stabilized during gait. Methods The participants were 20 asymptomatic subjects. A four-segment kinetic foot model was used to calculate and estimate intrinsic foot joint moments, powers and angular velocities during gait. 3D angles between the joint moment and the joint angular velocity vectors were calculated for the intrinsic foot joints defined as follows: ankle joint motion described between the foot and the shank for the one-segment foot model (hereafter referred as Ankle), and between the calcaneus and the shank for the multi-segment foot model (hereafter referred as Shank-Calcaneus); joint motion described between calcaneus and midfoot segments (hereafter referred as Chopart joint); joint motion described between midfoot and metatarsus segments (hereafter referred as Lisfranc joint); joint motion described between first phalanx and first metatarsal (hereafter referred as First Metatarso-Phalangeal joint). When the vectors were approximately aligned, the moment was considered to result in propulsion (3D angle 120o) at the joint. When the vectors are approximately orthogonal (3D angle close to 90°), the moment was considered to stabilize the joint. Results The results showed that the four intrinsic joints of the foot are never fully propelling, resisting or being stabilized, but are instead subject to a combination of stabilization with propulsion or resistance during the majority of the stance phase of gait. However, the results also show that during pre-swing all four the joints are subject to moments that result purely in propulsion. At heel off, the propulsive configuration appears for the Lisfranc joint first at terminal stance, then for the other foot joints at pre-swing in the following order: Ankle, Chopart joint and First Metatarso-Phalangeal joint. Conclusions Intrinsic foot joints adopt a stabilized-resistive configuration during the majority of the stance phase, with the exception of pre-swing during which all joints were found to adopt a propulsive configuration. The notion of stabilization, resistance and propulsion should be further investigated in subjects with foot and ankle disorders.

Category: Basic Sciences/Biologics Introduction/Purpose: A scientifically sound validated foot and ankle specific outcome measure for different European languages is still missing. Indeed, language-specific cross cultural validation in other languages than English is largely absent. Some outcome measures were validated for specific pathologies such as hallux valgus, ankle arthritis or flatfoot. The European Foot and Ankle Society (EFAS) established in 2013 a Score Committee to develop, validate, and publish a new score, the “EFAS Score”, which is not specific for single pathologies for different European languages. The principal aim of this project was to develop and validate the EFAS Score simultaneously for different European languages. Methods: The EFAS Score was developed and validated in three stages: 1) item (question) identification, 2) item reduction and scale exploration, 3) confirmatory analyses and responsiveness. The following score specifications were chosen: scale/subscale (Likert 0-4), questionnaire based, outcome measure, patient related outcome measurement. For stage 3, data were collected pre- operatively and post-operatively at a minimum follow-up of 3 months and mean follow-up of 6 months. Item reduction, scale exploration, confirmatory analyses and responsiveness were executed using analyses from classical test theory and item response theory. Results: Stage 1 resulted in 31 general and 7 sports related questions. In Stage 2, a 6-item general EFAS Score was constructed using English, German, French and Swedish language data. In Stage 3, internal consistency of the scale was confirmed in seven languages: the original four languages, plus Dutch, Italian and Polish (Cronbach’s Alpha >0.86 in all language versions). Responsiveness was good, with moderate to large effect sizes in all languages, and significant positive association between the EFAS Score and patient-reported improvement. No sound EFAS Sports Score could be constructed. Conclusion: The multi-language EFAS Score has been successfully validated for orthopaedic foot and ankle surgery populations incorporating a wide variety of foot and ankle pathologies, including language-specific validation in seven languages so far (English, German, French, Swedish, Dutch, Italian, Polish). Validation for other languages (Danish, Finnish, Norwegian, Portuguese, Spanish, Turkish) is in progress. All validated score versions are freely available at www.efas.co .

Category: Ankle Arthritis Introduction/Purpose: In 2015-2016, renewal of the 5-yearly French health insurance financing of TAR requires exhaustive data. The French Foot Surgery Society (AFCP – project initiator and promoter), Lyon University Hospitals Clinical Research Unit (administrator and scientific manager) and manufacturers (operational financers) therefore launched a national TAR registry on June 18, 2012 (CNIL data protection approval). For each TAR, there are 3 forms: prosthesis patient data, reoperation, monitoring (optional).We present results for the first 3 years. Methods: Under the 3-party contract, manufacturers pay for 6-monthly reports and €32 per prosthesis to cover the reminder procedure (each company gives the Research Unit a monthly list of surgeons, and the Unit sends out 3 reminders to those who have not entered data). Every surgeon implanting TARs must file a pre-registration formula on the website; after verification, the administrator sends the center number and personal login. Registration takes 3-5 minutes; implant ID number is automatically provided after complete data input. Then surgeons distribute a legal information sheet plus passport (patients can alert the research unit directly in case of re-operation). From June 2012 to June 2015, 1276 of the 1,612TARs implanted in France were registered (79.2%): 514 Salto, 353 SaltoTalaris, 307 Hintegra, 81 Star, 21 Akile. 202 centers implanted TARs: 127 registered TARs in the Registry, 75 registered none. Ten centers registered more than 30 (737 TARs), and 36 only one; surgeon investment was proportional to number of TARs (41% registration rate in centers registering one TAR to 94% in centers registering more than 10 TARs). Results: Mean age at implantation was 63.4 years (18-91 years); etiology was mainly post-traumatic (49%), osteoarthritis on laxity (19%), primary (17%) or inflammatory (7%), with some hindfoot misalignment (21% varus >5°, 11% valgus >5°). Surgery comprised: 97% standard implants (MB thickness mainly 4 mm (26%) or 5 mm (25%)); tourniquet time, 89 min; malleolar fracture, 6.4%; associated Achilles lengthening, 20.9%; ligament plasty, 8.6%; osteotomy, 4.9%; arthrodesis, 2.3%. 528 patients (41.4%) had at least 1 follow-up form (wound healing delay 6.8%, infection 0.7%, DF 9.9°, PF 22.1°). At 3 years, 74 patients (5.8%) were reoperated on (17 patients (2%) at 2 yrs): i.e. 89 reoperations (1-4/patient). 51 patients (4%) had revision without implant removal (arthrolysis 33%, complementary osteotomy 11.5%, Achilles lengthening 9.8%, ligament plasty 6.6%, etc); 9 (0.7%) with partial TAR change (tibia 6 – talus 3); 14 (1.1%) with TAR removal (4 re-do TAR, 8 arthrodesis, 2 temporary spacer before arthrodesis). Conclusion: Follow-up was insufficient to assess survival. This registry procedure, closely followed by the health authorities, has overcome French surgeons’ aversion for registries (exhaustiveness 2% for French Hip registry). Exhaustiveness could be improved if taken into account for surgeons’ accreditation. But an independent annual telephone audit requested by HAS (French Health Authority) showed that at 1 year the registry detected only 29% of reoperations vs phone call survey of registry patients: registries are not the gold standard and probably overestimate the real survival rate.

Category: Other Introduction/Purpose: For 30 years THA and TKA have been gold standards for severe osteoarthritis. Results are not better in TAA than in ankle arthrodesis according to meta-analysis. Ten year TAA survivorship improved from 80 to 90% but is still worse than in THA and TKA. It is generally thought that THA has better results than TKA and TAA but there have been few quality of life comparative studies. The present study compared functional results, quality of life (QoL) and sports capacity following ankle (TAA), hip (THA) and knee arthroplasty (TKA). Methods: Three continuous series (69 TAA, 716 THA, 121 TKA) operated on by 3 senior surgeons, from 2006 to 2011, were matched for age and follow-up. Patients older than 80 years, multiple arthroplasty in different joints, rheumatoid arthritis and revision of components were excluded. Questionnaires on general quality of life (SF-36, WOMAC, Bonnin's sports questionnaire) and specific function (AOFAS, FAAM, IKS function, Harris) were sent to 3 series (42 TAA, 132 THA and 60 TKA). Statistical analysis used JMP Pro 9.0.0 software. 95% of TAA (42 patients, FU 35±16.2 months, age 63±10.1 years), 82.9% of THA (132 patients, FU 31.5±6.7 months, age 64±8.4 years) and 86.6% of TKA patients (60 patients, FU 31.4±9.4 months, age 71.8±6.7 years) responded. Results: 76.3% of TAA, 90.2% of THA and 84.6% of TKA patients were very satisfied or satisfied. Global SF-36 scores were 58.5±18.5 (TAA), 64.5±16 (THA) and 55.3±17.4 (TKA). Le Global WOMAC scores (/96pts. the higher the more severe) were 25.3±18.3 (TAA), 14.2±16.7 (THA), and 21.4±24.5 (TKA). Functional results were good or excellent in 60.6% of TAAs (AOFAS score), 78.3% of THAs (Harris score) and 48.7% of TKAs (IKS score). Activity of Daily Living FAAM subscales (/84pts) were 54.9±22.5; Sports FAAM subscales (/32pts) 8.2±9.1. Sporting activity was frequent: 86.8% (TAA), 86.9% (THA) and 74.4% (TKA), and pain-free in 44%, 66.8% and 62.9% respectively. TAA patients practiced a mean 3.3 sports, THA patients 2.5 and TKA patients 1.9. Conclusion: QoL on SF36 was better in THA, and equivalent between TAA and TKA. Specific scores were less relevant than general scores. Sports activities were most restricted in TKA. This encourages the use of TAA. There is still work to do to improve specific scores.

Category: Midfoot/Forefoot Introduction/Purpose: MTP-1 arthrodesis allows effective correction of both inter-metatarsal M1M2 and M1P1 angles. Undercorrection of wide M1M2 angle after MTP-1 arthrodesis causes persistently wide forefoot, metatarsalgia and unaesthetic gap between first and second toes. In severe deformities, Rippstein recommended supplementary first metatarsal osteotomy or cuneo-metatarsal arthrodesis. The present study sought to investigate correction of inter-metatarsal M1M2 angle after MTP-1 arthrodesis according to aetiology and pre-operative deformity severity. Methods: A prospective continuous series (June 2007- March 2011) included 208 patients: 48% severe hallux valgus and/or osteoarthritis, 18% hallux rigidus, 16% rheumatoid osteoarthritis, 13% revision, 5% hallux varus; mean age, 62.4±9.9 years (19-87 years). All patients were operated on by a single senior surgeon with the same technique: articular surface reaming (cup-ball), osteosynthesis with titanium anatomical plate (Fyxis-Biotech) and the same rehabilitation procedure. Pre- and post-operative hallux positions were analysed on antero-posterior and lateral weightbearing views. M1M2 and M1P1 were measured according to American Orthopaedic Foot and Ankle Society guidelines. Results: Mean follow-up was 18.6±12.4 months; fusion rate, 97%; 5% plate removal. Mean M1P1 angle was 33.8±19.7° (-45° to 67°) preoperatively, and 13.4±5.3° (0-32°) at follow-up; M1M2, 14.2±5.4° (0° to 26°) and 6.5± 2.3° (0-12°) respectively. M1M2 angle was < 15° in 97 patients, 15-19° in 78 and ≥20° in 33 preoperatively, and respectively 5.8±2.1° (0-10°), 6.7±2.2° (0-10°) and 8.1±2.4° (3-12°) at follow-up. No significant differences were observed according to aetiology. M1M2 angle was >10° in only 2 patients (0.9%) associated with cuneometatarsal osteoarthritis. Improvement increased with severity of preoperative M1M2 angle (p < 0.05). However, mean postoperative M1M2 angle in the severe group was nevertheless wider than in the moderate group. Conclusion: MTP1-arthrodesis corrected M1M2 angle even in severe deformity, of whatever aetiology, in agreement with the literature, whereas Rippstein recently recommended supplementary M1 osteotomy or C1M1 arthrodesis for preoperative M1M2 angle >10°. Pydah correlated preoperative and postoperative intermetatarsal angle with a regression line, without recommending any secondary procedure to improve M1M2 angle. In severe increased preoperative M1M2 angle, we do not recommend associating systematic C1M1 arthrodesis or basal metatarsal osteotomy to MTP-1 arthrodesis, but suggest that additional basal metatarsal osteotomy or C1M1 fusion might be required only in exceptional associated degenerative C1M1 joint.

Category: Midfoot/Forefoot Introduction/Purpose: At present, there are no guidelines for foot-surgery procedures that can be performed in day-surgery. The aim of our study was to evaluate early postoperative pain after forefoot day-surgery compared to a conventional hospitalization. The hypothesis was that patients operated in day-surgery showed as much pain as those hospitalized, without more complications. Methods: All patients operated for forefoot surgery by one senior surgeon (JLB) were included; those eligible for day-surgery according to SFAR (French Society of Anesthesia and Reanimation) recommendations were operated in day-surgery. Patients were distributed into 4 groups according to surgical procedure: 1.minor procedure (isolated lesser ray) – 2.light (isolated first ray) – 3.intermediate (first ray plus one or two lesser rays) – 4.complex (all forefoot). Patients living alone, further than 50 kilometres from our hospital, or in group 4 were hospitalized for 48 hours. The study included 317 patients; 40% were operated on in day-surgery. Those hospitalized were significantly older (60±3.8 versus 55±3.9, p=0.0006) and with higher ASA scores (p=0.0024) without difference in comorbidity. Main etiology was hallux valgus (70% in both groups); revision surgery counted for 9% of etiologies in the day-surgery versus 14% in the hospitalization group. Results: The highest daily pain rate was on day 1 (4.2/10±2.5 in day-surgery versus 4.4/10±2.4 in hospitalization, p=0.53) without significant difference between groups. Pain was evaluated as extreme (≥8/10) by 9% of patients in day-surgery versus 11% of those hospitalized. We found a statistically significant difference at day 0 for the light surgical procedures (category 2), with higher pain in day-surgery (4.4± 2.4 versus 3.3± 2.5, p=0.02). Concerning anaesthesia, time to recovery of sensitivity after nerve block was comparable regardless of the type of hospitalization or surgical procedure (6.0 hours ± 3.7 in day-surgery versus 5.8 hours ± 5.4, p=0.9). One patient in the day-surgery group had crossover for bleeding. Concerning the self-assessment questionnaire, patients operated in day-surgery described significantly more alertness and attention disturbances following surgery (p=0.01), and more frequent disappearance of pain after day 7 (p=0.02). Conclusion: There was no significant difference in pain or complications between groups. All patients were very satisfied. We can then reasonably recommend performing forefoot day-surgery in good collaboration with the anaesthetist and patient, without exposing the latter to greater pain and further complications.

Category: Ankle Arthritis Introduction/Purpose: Ten-year Total Ankle Replacement (TAR) survivorship improved from 80 to 90%. But periprosthetic osteolysis associated with implant subsidence remains the main problem, with difficult revision surgery by arthrodesis; bone defect requiring massive graft. We proposed an original approach using porous tantalum as spacer to fill the defect and reinforce arthrodesis-reconstruction Methods: From October 2013 to September 2015, eleven patients underwent TAR revision (7 AES TM, 2 Hintegra TM, 1 Salto TM, 1 Albatros TM) by ten TTC arthrodesis and one ankle arthrodesis using tantalum (with Zimmer Trabecular Metal Ankle Interpositional SpacerTM introduced in July 2013). All patients were followed up prospectively clinically and radiologically (X-rays and CT scan at 4-6 months, and 1 year); and a bone scan with SPECT- CT if residual pain at one year. Mean age was 53.2 yrs [37-82yrs] at TAR, 66.6 yrs [41–90 yrs] at revision-arthrodesis, with a mean interval of 7.2 yrs [2-12yrs]. Results: We used a tantalum cone (25-40 mm height) and osteosynthesis by a retrograde nail in 10 TTC arthrodesis cases (Tornier–AFN611TM, 10 or 12 mm diameter, 6° or 11° lateral angulation) associated or not to a complementary anterior sub- talar screw (Unima-BiotechTM 4.5 mm), and a double anterior plate in one ankle arthrodesis case . Tantalum implants were surrounded by antologous bone graft (1 posterior iliac crest, 10 iliac wing harvested with hip reamers) mixed with Lyophylized fragmented Human Bone. Postoperatively, patients were 6 weeks without weight-bearing, followed by 2 months of boot with weight-bearing. At a mean 1 year follow-up (4 -18 mo), ankle fusion was confirmed on CT in all cases but with doubt for 2 cases. But there remained three case of unexplained residual severe pain associated with hyperactivity on bone scan: incomplete fusion (difficult to assess on CT due to tantalum)? impingement between locking-screws and Tantalum? Conclusion: Porous tantalum had biological and biomechanical properties close to those of natural bone. The use of Trabecular MetalTM in hip, knee, spine surgery recently demonstrated efficacy; but there are few recent publications in TAR revision. Our preliminary results are encouraging; tantalum allows primary stability of reconstruction. Is it better than Titanium cages? We need longer follow-up to analyze integration and fusion; and to check the residual pain in some cases.