Introduction. Osteoarthritis in the foot and ankle affects approximately 30,000 patients annually in the UK. Evidence has shown that excess weight exacerbates foot pain, with significant increases in joint forces. However, despite the current trend for Clinical Commissioning Groups to ration surgery for obese patients, studies have not yet determined the effect of weight loss in obese patients with foot and ankle arthritis. Aim. Pilot study to investigate the effect of simulated weight loss on pain scores in obese patients with symptomatic foot and ankle arthritis. Methods. Following ethical approval, a prospective study of 17 obese patients (mean BMI 39.2, range 31.2 – 50.3) with foot and ankle arthritis was undertaken (BOFAS funded). Under physiotherapist supervision, patients walked for one minute on an anti-gravity treadmill, which allowed simulated weight reduction. Following baseline assessment, reduced BMI was simulated, starting at 20, rising in increments of 5, until each patient's usual BMI was reached. Pain was assessed using a Visual Analogue Scale (VAS). Repeated measures ANOVA was used to assess for significant changes in pain, comparing baseline with each simulated BMI category (significance set at p< 0.05). Results. Simulated weight loss caused a significant reduction in pain (p=0.005, power 0.91). Mean VAS pain scores improved by 24% (p=0.003) and 17% (p=0.040) for BMI categories 20 and 25, compared with baseline. Pain scores were not significantly different comparing BMI categories of 25 and 20. Conclusion. Simulated weight loss to normal BMI significantly decreased pain in obese patients with foot and ankle arthritis. The use of the anti-gravity treadmill to demonstrate the feeling of normal BMI has also provided motivation to several patients to lose weight. The current study could be used to power future studies to investigate the effects of weight loss in foot and ankle patients

Aims. The surgical management of ankle arthritis with tibiotalar arthrodesis is known to alter gait, as compared with normal ankles. The purpose of this study was to assess post-operative gait function with gait before arthrodesis. Patients and Methods. We prospectively studied 20 patients who underwent three-dimensional gait analysis before and after tibiotalar arthrodesis. Cadence, step length, walking velocity and total support time were assessed. Kinetic parameters, including the moment and power of the ankle in the sagittal plane and hip power were also recorded. Results. Significant improvement was recorded across numerous parameters compared with pre-operative measurements. Temporal-spatial data demonstrated a significant increase in step length (p = 0.003) and velocity (p = < 0.001). Total support time decreased for the unaffected limb (p = 0.01). Kinematic results demonstrated that in the affected limb, total sagittal range of movement did not change significantly (p = 0.1259). However, the arc of movement had a near congruent shift with mean maximal dorsiflexion increasing from 5° (-17° to 16°) to 12° (5° to 18°) (p < 0.001) and mean maximal plantarflexion decreasing from 6.8° (6° to 21°) to 0.9° (-9° to 8°) (p = 0.003). Mean hip joint range of movement increased by 6° (-7° to 24°; p = 0.003). Kinetic results demonstrated no statistically significant change in ankle power (p = 0.1292). However, there was an increase in ankle moment (p = 0.04) and hip power (p = 0.01) in the surgically treated extremity. Sagittal plane range of movement was not reduced after tibiotalar fusion. Conclusion. Although following tibiotalar arthrodesis the gait demonstrated never matched the gait shown in unaffected ankles, compared with the pre-operative analysis there was improvement in numerous temporal-spatial, kinematic, and kinetic measures. Cite this article: Bone Joint J 2016;98-B:1369–75

Aim. Young patients with ankle arthritis that remains symptomatic in spite of conservative treatment and following arthroscopic debridement are usually offered either ankle fusion or ankle replacement. Both these options are far from ideal in this age group. The aim of this study was to evaluate functional outcomes following ankle distraction to determine whether it is a reliable alternative for the treatment of ankle arthritis in young adults. Material and methods. Data was collected prospectively for 15 patients (9 males and 6 females, mean age 31.9 years) with “stage 2” ankle arthritis who failed conservative treatment and continued to be symptomatic following arthroscopic ankle debridement. Distraction of 8 mm was done using a dynamic constrained ankle circular frame and all patients were allowed full weight bearing all through the distraction process. The subjective functional evaluation was based on the American Orthopaedic Foot and Ankle Score (AOFAS), the Foot Disability Index (FADI) and the Visual Analogue Score (VAS). In 10 patients the Manchester Oxford Foot questionnaire (MOXFQ) and the Short Form (SF) 12 patient satisfaction questionnaire were also filled preoperatively and at final follow up. Results. At a minimum follow-up of 24 months (mean 34.4) none of the patients required fusion or replacement. There was a significant improvement in all the functional outcome scores. There was also a significant improvement in the ankle joint space on weight bearing x-rays. Conclusion. Based on these results the use of ankle distraction can be considered a useful option for the treatment of symptomatic “stage 2” ankle arthritis in young adults. Longer-term follow-up and comparison with alternative techniques will be required to evaluate the true effectiveness of this treatment option

Aims

A multicentre, randomized, clinician-led, pragmatic, parallel-group orthopaedic trial of two surgical procedures was set up to obtain high-quality evidence of effectiveness. However, the trial faced recruitment challenges and struggled to maintain recruitment rates over 30%, although this is not unusual for surgical trials. We conducted a qualitative study with the aim of gathering information about recruitment practices to identify barriers to patient consent and participation to an orthopaedic trial.

Aims. This is a multicentre, non-inventor, prospective observational study of 503 INFINITY fixed bearing total ankle arthroplasties (TAAs). We report our early experience, complications, and radiological and functional outcomes. Methods. Patients were recruited from 11 specialist centres between June 2016 and November 2019. Demographic, radiological, and functional outcome data (Ankle Osteoarthritis Scale, Manchester Oxford Questionnaire, and EuroQol five-dimension five-level score) were collected preoperatively, at six months, one year, and two years. The Canadian Orthopaedic Foot and Ankle Society (COFAS) grading system was used to stratify deformity. Early and late complications and reoperations were recorded as adverse events. Radiographs were assessed for lucencies, cysts, and/or subsidence. Results. In all, 500 patients reached six-month follow-up, 420 reached one-year follow-up, and 188 reached two-year follow-up. The mean age was 67.8 years (23.9 to 88.5). A total of 38 patients (7.5%) presented with inflammatory arthritis. A total of 101 (20.0%) of implantations used patient-specific instrumentation; 167 patients (33.1%) underwent an additional procedure at the time of surgery. A total of seven patients died of unrelated causes, two withdrew, and one was lost to follow-up. The mean follow-up was 16.2 months (6 to 36). There was a significant improvement from baseline across all functional outcome scores at six months, one, and two years. There was no significant difference in outcomes with the use of patient-specific instrumentation, type of arthritis, or COFAS type. Five (1.0%) implants were revised. The overall complication rate was 8.8%. The non-revision reoperation rate was 1.4%. The 30-day readmission rate was 1.2% and the one-year mortality 0.74%. Conclusion. The early experience and complications reported in this study support the current use of the INFINITY TAA as a safe and effective implant in the treatment of end-stage ankle arthritis. Cite this article: Bone Joint J 2021;103-B(7):1270–1276

Aims

The Vantage Total Ankle System is a fourth-generation low-profile fixed-bearing implant that has been available since 2016. We aimed to describe our early experience with this implant.

Little is known about the long-term outcome of mobile-bearing total ankle replacement (TAR) in the treatment of end-stage arthritis of the ankle, and in particular for patients with inflammatory joint disease. The aim of this study was to assess the minimum ten-year outcome of TAR in this group of patients.

We prospectively followed 76 patients (93 TARs) who underwent surgery between 1988 and 1999. No patients were lost to follow-up. At latest follow-up at a mean of 14.8 years (10.7 to 22.8), 30 patients (39 TARs) had died and the original TAR remained in situ in 28 patients (31 TARs). The cumulative incidence of failure at 15 years was 20% (95% confidence interval (CI) 11 to 28). The mean American Orthopaedic Foot and Ankle Society (AOFAS) ankle–hindfoot score of the surviving patients at latest follow-up was 80.4 (95% CI 72 to 88). In total, 21 patients (23 TARs) underwent subsequent surgery: three implant exchanges, three bearing exchanges and 17 arthrodeses. Neither design of TAR described in this study, the LCS and the Buechel–Pappas, remains currently available. However, based both on this study and on other reports, we believe that TAR using current mobile-bearing designs for patients with end-stage arthritis of the ankle due to inflammatory joint disease remains justified.

Cite this article: Bone Joint J 2013;95-B:1656–61.

In a retrospective study we compared 32 HINTEGRA total ankle replacements (TARs) and 35 Mobility TARs performed between July 2005 and May 2010, with a minimum follow-up of two years. The mean follow-up for the HINTEGRA group was 53 months (24 to 76) and for the Mobility group was 34 months (24 to 45). All procedures were performed by a single surgeon.

There was no significant difference between the two groups with regard to the mean AOFAS score, visual analogue score for pain or range of movement of the ankle at the latest follow-up. Most radiological measurements did not differ significantly between the two groups. However, the most common grade of heterotopic ossification (HO) was grade 3 in the HINTEGRA group (10 of 13 TARs, 76.9%) and grade 2 in the Mobility group (four of seven TARs, 57.1%) (p = 0.025). Although HO was more frequent in the HINTEGRA group (40.6%) than in the Mobility group (20.0%), this was not statistically significant (p = 0.065).The difference in peri-operative complications between the two groups was not significant, but intra-operative medial malleolar fractures occurred in four (11.4%) in the Mobility group; four (12.5%) in the HINTEGRA group and one TAR (2.9%) in the Mobility group failed (p = 0.185).

Cite this article: Bone Joint J 2013;95-B:1075–82.

Background. Total Ankle Replacement (TAR) is an established treatment option for end-stage ankle arthritis. We analysed at minimum, 10-year patient-reported and clinical outcomes of 156 TARs from a single centre. We specifically compared outcomes between patients under 60 and over 60 at time of surgery. Methods. Data was collected retrospectively from our departmental patient database. It included all patients who underwent a TAR by a single surgeon between 2006 and 2010 and patients were divided into those under 60 and those over 60 at the time of surgery. Patient reported outcomes (PROMs), including WOMAC, SF-36 and patient satisfaction scores and complications were analysed preoperatively and at one, two, five and over 10 years postoperatively. Results. There were 156 patients included in this analysis, 61 were under 60 (mean age 50.29) and 95 were over 60 (mean age 69.12). A total of 12 patients had revision surgery, (nine in the under 60 group) and 52 patients were deceased at the time of analysis (10 in the under 60 group). At one year the over 60 group had less pain and better functional scores (p=0.02, p=0.017). At two, five and ten years there was no statistical difference in pain and function between groups. At two years the over 60s reported less stiffness and quicker return to activities of daily living (p=0.007, p=0.001). However, at five and 10 years there was no statistical difference in any domain. Conclusions. This study demonstrates that age does not correlate with a significant difference in pain or functional outcomes in patients who have TAR, at over 10 years follow up. The higher revision rates in the younger group may correlate with higher functional demand and lower mortality rate

Background. Total ankle replacements (TARs) are becoming increasingly more common in the treatment of end stage ankle arthritis. As a consequence, more patients are presenting with the complex situation of the failing TAR. The aim of this study was to present our case series of isolated ankle fusions post failed TAR using a spinal cage construct and anterior plating technique. Methods. A retrospective review of prospectively collected data was performed for 6 patients that had isolated ankle fusions performed for failed TAR. These were performed by a single surgeon (IW) between March 2012 and October 2014. The procedure was performed using a Spinal Cage construct and grafting in the joint defect and anterior plating. Our primary outcome measure was clinical and radiographic union at 1 year. Union was defined as clinical union and no evidence of radiographic hardware loosening or persistent joint lucent line at 1 year. Results. The mean follow-up was 37.3 months (SD 13.2). Union was achieved in 5 of the 6 patients (83%). One patient had a non-union that required revision fusion incorporating the talonavicular joint that successfully went on to unite across both joints. Another patient had radiographic features of non-union but was clinically united and asymptomatic and one required revision surgery for a bulky symptomatic lateral malleolus with fused ankle joint. Conclusion. The failing TAR presents a complex clinical situation. After removal of the implant there is often a large defect which if compressed leads to a leg length discrepancy and if filled with augment can increase the risk of non-union. Multiple methods have been described for revision, with many advocating fusion of both the ankle joint and subtalar joint. We present our case series using a spinal cage and anterior plating that allows preservation of the subtalar joint and a high rate of union

Background. The importance of total ankle replacement (TAR) implant orientation in the axial plane is poorly understood with major variation in surgical technique of implants on the market. Our aims were to better understand the axial rotational profile of patients undergoing TAR. Methods. In 157 standardised CT Scans of end-stage ankle arthritis patients planning to undergo primary TAR surgery, we measured the relationship between the knee posterior condylar axis, the tibial tuberosity, the transmalleolar axis(TMA) and the tibiotalar angle. The foot position was measured in relation to the TMA with the foot plantigrade. The variation between medial gutter line and the line bisecting both gutters was assessed. Results. The mean external tibial torsion was 34.5±10.3°(11.8–62°). When plantigrade the mean foot position relative to the TMA was 21±10.6°(0.7–38.4°) internally rotated. As external tibial torsion increased, the foot position became more internally rotated relative to the TMA(pearson correlation 0.6;p< 0.0001). As the tibiotalar angle became more valgus, the foot became more externally rotated relative to the TMA(pearson correlation −0.4;p< 0.01). The mean difference between the medial gutter line and a line bisecting both gutters was 4.9±2.8°(1.7°-9.4°). More than 51% of patients had a difference greater than 5°. The mean angle between the medial gutter line and a line perpendicular to the TMA was 7.5°±2.6°(2.8°-13.7°). Conclusion. There is a large variation in rotational profile of patients undergoing TAR, particularly between the medial gutter line and the transmalleolar axis. Surgeon designers and implant manufacturers need to develop consistent methods to guide surgeons towards judging appropriate axial rotation of their implanton an individual basis. We recommend careful clinical assessment and CT scanspre-operatively to enable the correct rotation to be determined

Introduction. Total ankle arthroplasty (TAA) is an increasingly popular treatment option for patients with end-stage ankle arthritis. However, for most implant systems, failure rates of 10–20% have been reported within the first 10 years after primary TAA. Pain is the primary symptom that indicates failure of TAA but cause of it can be difficult to establish. Methods. All patients who underwent a primary TAA at our center were included in the study. The clinical outcomes were studied for patients requiring a further revision procedure following primary TAA. The reasons for revision surgery and outcomes of surgery were analyzed using appropriate inferential statistical tests. Results. Between 2007 and 2018, 42 primary TAA required revisions in 40 patients. There were 25 men (59.5%) and 15 women (35.7%) with mean age of 57.5 years the time of primary TAA. All patients had undergone primary procedure at a mean duration of 3.5 years previously (range: 3 months to 10 years). Of the total revision procedures, 12/40 (30%) of revisions were carried out due to malalignment, 10/42 (23.8%) due to loosening of the implants or bone subsidence, 5/42 procedures (11.9%) following infection, 4/42 (9.5%) due to polyethylene migration, 1/42 (2.3%) due to fracture and 1/42 (2.3%) due to Charcot arthropathy. In 9/42 (21.4%) cases, imaging showed no objective reason for pain. 50% of patients who underwent revision TAA reported 78.5% satisfaction with results of surgery at 2 years follow up post-operatively. Conclusion. Major reasons for revising primary TAR at our centre are mal-alignment, implant loosening / bone subsidence and suspicion of infection and pain. In-spite of undergoing a complex revision surgery, patients report 78.5% satisfaction from outcomes of surgery

Introduction. Total ankle replacement as a valid treatment for end stage ankle arthritis, is gaining popularity and every year there is an increasing number of procedures. With revision rates as high as 21% at 5 years and 43% at 10 years there is a need for understanding and reporting the outcome of revision ankle replacement. Our aim was to study the patient reported outcomes following revision TAR with a minimum of 2 year follow up. Methods. All patients that underwent a revision total ankle replacement between 2012 and 2016 were included in the study. All patients received a post-operative questionnaire comprising of MOX-FQ score, EQ-5D (UK) and Foot and Ankle outcomes scores (FAOS) and patients satisfaction questionnaire with a minimum of 2 years follow up. Results. 33 patients had a revision total ankle replacement between 2012 and 2016. 2 patients were deceased therefore 31 patients were included in the study. 4 patients declined participation for completing questionnaires. We received 15/27 (55.5%) completed questionnaires. The mean MOX-FQ average domain score for pain was (50.6 ± 26.9), walking/standing (62.4 ± 36.5) and social function was (43.7± 31.0). The mean FAOS scores were (52.5 ± 30.6; pain), (54.5 ± 29.2; symptoms), (62.1 ± 30.5; ADL) and (35.5 ± 28.2; for quality of life). The mean overall health score today for EQ-5D was 73.9/100. 50% of patients were satisfied with the pain relief and return to sports and recreation obtained following the operation, 57% were satisfied with the improved in daily activities. 78.5% were overall satisfied with the results from surgery. Conclusion. Revision total ankle replacement gives overall satisfactory results demonstrated from patients reported outcomes at a minimum of 2 years following surgery

Background. Open or arthroscopic ankle fusion (AAF) is a successful operative treatment for end-stage ankle arthritis. Evidence suggest that AAFs have better outcomes. In addition to the operative technique other patient-factors can influence outcomes. The most significant complication of ankle fusion is a non-union. To better understand the risk factors related to this we undertook a retrospective investigation of primary AAFs. Methods. We reviewed all AAFs conducted at our institution over a 10-year period. Patients excluded if they had simultaneous fusion of neighbouring joints or were lost to follow-up. The primary outcome variable was radiographic union. Other operative complications were analysed as secondary outcomes. Two hundred and eighty-four eligible AAFs in 271 patients were performed over the study period. Results. The overall non-union rate was 7.7 %. Univariate logistic regression analysis found that smoking (6.2% non-union in non-smokers vs 24% in smokers) and prior triple fusion (5.5% non-union in the absence of prior triple fusion vs 70% in the presence of a prior triple fusion) were independent risk factors for non-union. Multivariate analysis showed that only prior triple fusion was predictive (OR 40.0 [9.4,170.3], p < 0.0001). Increasing age, obesity (BMI >30), surgical grade (trainee vs consultant), diabetes or the degree of weightbearing status post-operatively were not significant risk factors of non-union. The leading cause of reoperation was the removal of metal (18%). There were 5 superficial (1.8%) and 4 deep (1.4%) infections. Kaplan-Meier survival analysis showed a 75% ‘survivorship’ of the subtalar joint at 10 years following an arthroscopic ankle fusion. Conclusion. This is the largest case series of AAFs in the literature and the first to demonstrate that patients who had an AAF performed after a previous triple fusion have unacceptably high non-union rates and may benefit from other surgical options. This study data could also useful for patient consenting purposes

Introduction. Primary ankle arthroplasty (TAR) is increasingly used to treat end-stage ankle arthritis. Reported revision rates of TAR vary from 8.5% to 11.1% at 9 years. Revision surgery remains technically challenging with options ranging from simple joint debridement to tibio-talar-calcaneal fusion. The efficacy of these procedures remains unclear and there is no consensus on optimal revision options. Methods. A retrospective cohort study was performed of all patients undergoing surgery for a failed primary TAR at the Nuffield Orthopaedic Centre (2004–2021). TAR failure was determined by clinical assessment, serial radiographs and CT scans. Primary outcome measures included type and time of index surgery post TAR. Secondary outcomes included frequency of re-operations, post-operative complications, patient reported outcomes and union rate (for revision arthrodesis procedures). Results. 70 failed TARs in 69 patients (35M:34F, mean 65.7 years, s.d.=11.6) underwent re-operation a mean of 6.24 years (range 1–30) post primary. In total, 107 operations were performed including revision fusion (n=50), revision arthroplasty (n=14), bearing exchange (n=9) and joint clearance (n=9). The overall revision fusion union rate was 73.5% over a mean of 12.5 months (s.d.=7.6). 16/23 (69.6%) Tibio-Talo-Calcaneal and 9/12 (75%) ankle fusions (previous subtalar/triple fusion) using a hindfoot nail united over a mean 11.4 months (s.d.=6.0) and 15 months (s.d.=9.48) respectively. Only 64% of ankle fusions using screws alone united (mean=10.6 months, s.d.=8.14). The average post-operative MOXFQ score was 28.3 (s.d.=19.3). 73% said the operation improved their function and would recommend it to a friend/family member. Conclusion. Despite low post-operative MOXFQ scores, over 70% of patients were satisfied with re-operation for a failed TAR. Over 26% of all TAR revision fusions fail to unite with the highest non-union rates observed post ankle arthrodesis with screws alone (36.4%)

Ankle fusion (AF), a durable intervention for ankle arthritis, has been the management of choice but restricts mobility. Recently, total ankle replacement (TAR) has been offered to patients looking to maintain mobility. The aim was to compare the biomechanics of AF and TAR while walking on inverted and everted slopes which create a greater demand for complex foot mobility than level walking. A ten-camera motion detection setup captured trials as patients walked in both directions over a 5⁰ lateral slope with embedded force plates. Moments (Nm/Kg) across the knee and ankle were exported from Visual 3D in the sagittal and frontal plane, and data were reported as means with 95% confidence intervals. 15 patients were recruited (6 TAR, 9 AF). The median age, follow-up and BMI was 67 years, 4 years and 35.8 kg/m² in AF, and 73 years, 7 years and 28.1 kg/m² in TAR, respectively. During inverted slope walking (4 TAR, 7 AF), abduction moments across (i) the knee: TAR 0.38 (0.37–0.39) vs AF 0.37 (0.27–0.52) and (ii) the ankle: TAR 0.20 (0.13–0.27) vs AF 0.25 (0.18–0.32), and extension moments across (i) the knee: TAR 0.68 (0.38–0.97) vs AF 0.85 (0.69–1.01) and (ii) the ankle: TAR 1.46 (1.30–1.62) vs AF 1.30 (1.08–1.52). During everted walking (5 TAR, 7 AF), abduction moments across (i) the knee: TAR 0.41 (0.30–0.52) vs AF 0.46 (0.27–0.66) and (ii) the ankle: TAR 0.24 (0.11–0.38) vs AF 0.26 (0.18–0.33), and extension moments across (i) the knee: TAR 0.76 (0.54–0.99) vs AF 0.93 (0.72–1.14) and (ii) the ankle: TAR 1.39 (1.19–1.59) vs AF 1.26 (1.04–1.48). There were no differences in abduction moments during inverted or everted slope walking. However, patients with AF had increased extension moments across the knee, particularly on inverted slopes, suggesting that AF creates a greater demand for knee compensation than TAR

Aims. We report the medium-term outcomes of a consecutive series of 118 Zenith total ankle arthroplasties (TAAs) from a single, non-designer centre. Methods. Between December 2010 and May 2016, 118 consecutive Zenith prostheses were implanted in 114 patients. Demographic, clinical, and patient-reported outcome measures (PROMs) data were collected. The endpoint of the study was failure of the implant requiring revision of one or all of the components. Kaplan-Meier survival curves were generated with 95% confidence intervals (CIs) and the rate of failure calculated for each year. Results. Eight patients (ten ankles) died during follow-up, but none required revision. Of the surviving 106 patients (108 ankles: rheumatoid arthritis (RA), n = 15; osteoarthritis (OA), n = 93), 38 were women and 68 were men, with a mean age of 68.2 years (48 to 86) at the time of surgery. Mean follow-up was 5.1 years (2.1 to 9.0). A total of ten implants failed (8.5%), thus requiring revision. The implant survival at seven years, using revision as an endpoint, was 88.2% (95% CI 100% to 72.9%). There was a mean improvement in Manchester-Oxford Foot and Ankle Questionnaire (MOXFQ) from 85.0 to 32.8 and visual analogue scale (VAS) scores from 7.0 to 3.2, and overall satisfaction was 89%. The three commonest complications were malleolar fracture (14.4%, n = 17), wound healing (13.6%, n = 16), and superficial infection (12.7%, n = 15). The commonest reason for revision was aseptic loosening. No patients in our study were revised for deep infection. Conclusion. Our results show that Zenith survival rates are comparable with those in the literature for other implants and in the National Joint Registry (NJR). Overall patient satisfaction was high as were functional outcomes. However, the data highlight potential complications associated with this surgery. The authors believe that these figures support ankle arthroplasty as an option in the treatment of ankle arthritis. Cite this article: Bone Joint J 2021;103-B(4):696–703

Aims. Arthroplasty has become increasingly popular to treat end-stage ankle arthritis. Iatrogenic posterior neurovascular and tendinous injury have been described from saw cuts. However, it is hypothesized that posterior ankle structures could be damaged by inserting tibial guide pins too deeply and be a potential cause of residual hindfoot pain. Methods. The preparation steps for ankle arthroplasty were performed using the Infinity total ankle system in five right-sided cadaveric ankles. All tibial guide pins were intentionally inserted past the posterior tibial cortex for assessment. All posterior ankles were subsequently dissected, with the primary endpoint being the presence of direct contact between the structure and pin. Results. All pin locations confer a risk of damaging posterior ankle structures, with all posterior ankle structures except the flexor hallucis longus tendon being contacted by at least one pin. Centrally-aligned transcortical pins were more likely to contact posteromedial neurovascular structures. Conclusion. These findings support our hypothesis that tibial guide pins pose a considerable risk of contacting and potentially damaging posterior ankle structures during ankle arthroplasty. This study is the first of its kind to assess this risk in the Infinity total ankle system. Cite this article: Bone Jt Open 2021;2(7):503–508

Introduction. The prevalence of symptomatic osteoarthritis (OA) in the knee is 11–11% compared to 3.4–4.4% in the ankle. In addition to this, 70% of ankle arthritis is post-traumatic while the vast majority of knee arthritis is primary OA. Several reports have previously implicated biochemical differences in extracellular matrix composition between these joint cartilages; however, it is unknown whether there is an inherent difference in their transcriptome and how this might affect their respective functionality under load, inflammatory environment etc. Therefore, we have analysed the transcriptome of ankle and knee cartilage chondrocytes to determine whether this could account for the lower prevalence and altered aetiology of ankle OA. Methods. Human full-depth articular cartilage was taken from the talar domes (n=5) and the femoral condyles (n=5) following surgical amputation. RNA was extracted and next generation sequencing (NGS) performed using the NextSeq®500 system. Statistical analysis was performed to identify differentially regulated genes (p adj < 0.05). Data was analysed using Integrated Pathway Analysis software and genes of interest validated by quantitative PCR. Results. 809 genes were differentially expressed in this NGS study: 781 genes were significantly up-regulated and 27 significantly down-regulated in ankle cartilage with respect to knee. Preliminary analysis has identified several pathways which are differentially regulated including ‘inflammation mediated by cytokines’, ‘glutamate receptor pathway, ‘heterotrimeric-G-protein signalling pathways’, ‘WNT signalling’ and ‘integrin signalling’. Discussion. This is the first report identifying genes that are differentially expressed in ankle cartilage compared to the knee. Validation is currently being performed to ascertain the importance of these gene changes and correlation with their protein expression in the different joints. An understanding of the inherent biological differences in the cartilage between these two joints will provide invaluable insight into why the ankle is relatively spared from primary OA and the majority of ankle arthritis occurs following trauma

The relationship between hindfoot and forefoot kinematics is an important factor in the planning of ankle arthrodesis and ankle arthroplasty surgery. As more severe ankle deformities are corrected, improved techniques are required to assess and plan hindfoot to forefoot balancing. Gait analysis has previously been reported in patients with ankle arthritis without deformity. This group of patients have reduced intersegment motion in all measured angles. We have looked at a small group of patients with hindfoot deformity and ankle arthritis awaiting fusion or replacement. Using the Oxford Foot Model we have assessed lower limb kinematics with a focus on hindfoot to forefoot relationships. The results of our pilot study are in variance to previous studies in that we have shown that in the presence of hindfoot/ankle deformity, the forefoot range of motion increases. We feel that these data may impact on surgical planning