This study aimed to examine the effect of high tibial osteotomy (HTO) on the ankle and subtalar joints via analysis of static radiographic alignment. We hypothesised that surgical alteration of the alignment of the proximal tibia would result in compensatory distal changes. 35 patients recruited as part of the wider Biomechanics and Bioengineering Centre Versus Arthritis HTO study between 2011 and 2018 had pre- and postoperative full-length weightbearing radiographs taken of their lower limbs. In addition to standard alignment measures of the limb and knee (mechanical tibiofemoral angle, Mikulicz point, medial proximal tibial angle), additional measures were taken of the ankle/subtalar joints (lateral distal tibial angle, ground-talus angle, joint line convergence angle of the ankle) as well as a novel measure of stance width. Results were compared using a paired T-test and Pearson's correlation coefficient. Following HTO, there was a significant (5.4°) change in subtalar alignment. Ground-talus angle appeared related both to the level of malalignment preoperatively and the magnitude of the alignment change caused by the HTO surgery; suggesting subtalar positioning as a key adaptive mechanism. In addition to compensatory changes within the subtalar joints, the patients on average had a 31% wider stance following HTO. These two mechanisms do not appear to be correlated but the morphology of the tibial plafond may influence which compensatory mechanisms are employed by different subgroups of HTO patients. These findings are of vital importance in clinical practice both to anticipate potential changes to the ankle and subtalar joints following HTO but it could also open up wider indications for HTO in the treatment of ankle malalignment and osteoarthritis

Varus ankle osteoarthritis (OA) is typically associated with peritalar instability, which may result in altered subtalar joint position. This study aimed to determine the extent to which total ankle replacement (TAR) in varus ankle OA can restore the subtalar position alignment using 3-dimensional semi-automated measurements on WBCT. Fourteen patients (15 ankles, mean age 61) who underwent TAR for varus ankle OA were retrospectively analyzed using semi- automated measurements of the hindfoot based on pre-and postoperative weightbearing WBCT (WBCT) imaging. Eight 3-dimensional angular measurements were obtained to quantify the ankle and subtalar joint alignment. Twenty healthy individuals were served as a control groups and were used for reliability assessments. All ankle and hindfoot angles improved between preoperative and a minimum of 1 year (mean 2.1 years) postoperative and were statistically significant in 6 out of 8 angles (P<0.05). Values The post-op angles were in a similar range to as those of healthy controls were achieved in all measurements and did not demonstrated statistical difference (P>0.05). Our findings indicate that talus repositioning after TAR within the ankle mortise improves restores the subtalar position joint alignment within normal values. These data inform foot and ankle surgeons on the amount of correction at the level of the subtalar joint that can be expected after TAR. This may contribute to improved biomechanics of the hindfoot complex. However, future studies are required to implement these findings in surgical algorithms for TAR in prescence of hindfoot deformity

Objectives. The objective of this study was to quantify the relative movement between the articular surfaces in the tibiotalar and subtalar joints during normal walking in asymptomatic individuals. Methods. 3D movement data of the ankle joint complex were acquired from 18 subjects using a biplanar fluoroscopic system and 3D-to-2D registration of bone models obtained from CT images. Surface relative velocity vectors (SRVVs) of the articular surfaces of the tibiotalar and subtalar joints were calculated. The relative movement of the articulating surfaces was quantified as the mean relative speed (RS) and synchronization index (SI. ENT. ) of the SRVVs. Results. SI. ENT. and mean RS data showed that the tibiotalar joint exhibited translational movement throughout the stance, with a mean SI. ENT. of 0.54 (. sd. 0.21). The mean RS of the tibiotalar joint during the 0% to 20% post heel-strike phase was 36.0 mm/s (. sd. 14.2), which was higher than for the rest of the stance period. The subtalar joint had a mean SI. ENT. value of 0.43 (. sd. 0.21) during the stance phase and exhibited a greater degree of rotational movement than the tibiotalar joint. The mean relative speeds of the subtalar joint in early (0% to 10%) and late (80% to 90%) stance were 23.9 mm/s (. sd. 11.3) and 25.1 mm/s (. sd 9.5). , respectively, which were significantly higher than the mean RS during mid-stance (10% to 80%). Conclusion. The tibiotalar and subtalar joints exhibited significant translational and rotational movement in the initial stance, whereas only the subtalar joint exhibited significant rotational movement during the late stance. The relative movement on the articular surfaces provided deeper insight into the interactions between articular surfaces, which are unobtainable using the joint coordinate system. Cite this article: C-B. Phan, D-P. Nguyen, K. M. Lee, S. Koo. Relative movement on the articular surfaces of the tibiotalar and subtalar joints during walking. Bone Joint Res 2018;7:501–507. DOI: 10.1302/2046-3758.78.BJR-2018-0014.R1

A medializing calcaneal osteotomy (MCO) is one of the key inframalleolar osteotomies to correct progressive collapsing foot deformity (PCFD). While many studies were able to determine the hind- and midfoot alignment after PCFD correction, the subtalar joint remained obscured by superposition on plain radiography. Therefore, we aimed to perform a 3D measurement assessment of the hind- and subtalar joint alignment pre- compared to post-operatively using weightbearing CT (WBCT) imaging. Fifteen patients with a mean age of 44,3 years (range 17-65yrs) were retrospectively analyzed in a pre-post study design. Inclusion criteria consisted of PCFD deformity correct by MCO and imaged by WBCT. Exclusion criteria were patients who had concomitant midfoot fusions or hindfoot coalitions. Image data were used to generate 3D models and compute the hindfoot - and talocalcaneal angle as well as distance maps. Pre-operative radiographic parameters of the hindfoot and subtalar joint alignment improved significantly relative to the post-operative position (HA, MA. Sa. , and MA. Co. ). The post-operative talus showed significant inversion, abduction, and dorsiflexion of the talus (2.79° ±1.72, 1.32° ±1.98, 2.11°±1.47) compared to the pre-operative position. The talus shifted significantly different from 0 in the posterior and superior direction (0.62mm ±0.52 and 0.35mm ±0.32). The distance between the talus and calcaneum at the sinus tarsi increased significantly (0.64mm ±0.44). This study found pre-dominantly changes in the sagittal, axial and coronal plane alignment of the subtalar joint, which corresponded to a decompression of the sinus tarsi. These findings demonstrate the amount of alternation in the subtalar joint alignment that can be expected after MCO. However, further studies are needed to determine at what stage a calcaneal lengthening osteotomy or corrective arthrodesis is indicated to obtain a higher degree of subtalar joint alignment correction

Ankle sprains are very common, and usually tear or partly tear one or more of the ligaments on the outer side of the ankle. The ankle joint is only designed to move up and down, whereas there is another joint immediately below the ankle joint, called the subtalar joint, which is designed to do the tilting in and out movement. If the foot tilts over too far, the subtalar joint reaches the end of its movement and then the ankle ligaments stretch and tear. It is possible that variations of subtalar range of movement may contribute to ankle sprains or symptoms of weakness or instability. In particular, if the subtalar joint is unusually restricted in its movement, then the foot does not have to tilt far before the lateral ligaments tear. If on the other hand the subtalar joint is particularly mobile and has excessive movement, then the foot may go right over without actually tearing ligaments and feel insecure or unstable simply as a result of abnormal excessive movement. Recent studies have demonstrated what we have always suspected, that clinical examination and assessment of subtalar range of movement is highly unreliable. In order to accurately assess whether your subtalar range of movement is unusually restricted or excessive, the only standard and accurate method to date has been to obtain a CT scan. We are now undertaking a study to establish whether plain xrays with a small metal clamp applied to the heel might not be a simpler, cheaper, quicker and equally reliable method of assessment of subtalar movement. If you would like to know if your subtalar movement might be a contributing factor to either stiffness or insecurity of your ankle, we invite you to be examined clinically, by plain xrays at SPORTSMED•SA, and by a CT scan at Jones & Partners Radiology at Burnside. The xray and CT investigations would be bulk billed under Medicare so that you would not incur any personal cost and the information could well be helpful in assessing your ankle problem, or at least be reassuring that the subtalar joint has a normal range of movement. The investigations can be arranged through your treating doctor, physiotherapist or podiatrist or by contacting Dr Roger Paterson, Foot and Ankle Surgeon, or Mr Stephen Landers, his Research Assistant, on Ph: 8362 7788. The CT scan would be a very limited investigation resulting in minimum radiation exposure, comparable to the normal xrays. Further information on what is involved in having a CT scan is attached. Neither the CT scan nor the plain xrays should cause any more than minor discomfort as the foot is tilted through its full range of movement, or from the padded pressure of the G clamp. SPORTSMED•SA remains committed to excellence in treating active people of all ages, and through these investigations, we plan to further enhance the quality of assessment and care of people who suffer ankle problems

Background Tibiotalocalcaneal (TTC) arthrodesis is a salvage procedure for patients with severe disease of the ankle and subtalar joints. Method We report a series of 26 consecutive patients (26 feet) operated on by a single surgeon, in a single centre, over a 4-year period, with average follow up of 26 months (range 6–50). Mean age of the patients was 57 years (range 28–72). Subjects included 17 male and 9 females. Previously the patients had undergone between 0 to 6 operations, which were unsuccessful. All these patients had combined ankle and subtalar joint arthrodesis by an intramedullary nail device. Indications for surgery were pain except the Charcot joints. Only five patients did not have severe deformity pre-operatively. Aetiology included post-traumatic osteoarthritis, rheumatoid arthritis, psoriatic arthropathy, avascular necrosis, Charcot Marie Tooth disease, primary osteoarthritis, failed ankle replacement and alcohol-and diabetic-induced Charcot neuroarthropathy. Patients were assessed radiologically and by American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Scale, SF-12 and by patient satisfaction scores. Results Clinically and radiologically, 15 cases have solid union. Six patients have signs of radiological non-union/ delayed union but are clinically asymptomatic with no progressive deformity. Two patients required amputation (one non-union and one infected non-union). One patient is awaiting further surgery for infected non-union. Two patients have died of unrelated causes ~2 years post-surgery. Most patients (79%) are very satisfied with the procedure and 83% would undergo the procedure again. Conclusion These results suggest that salvage is possible in the majority of cases with combined ankle and subtalar joint arthrosis and severe deformity

Introduction: With increasing availability of CT scans their use in the investigation of the subtalar joint increases, whilst we continue to use plain x-ray. Using a standardised reporting protocol, we graded x-rays and CT scans to compare the diagnosis made using each modality. Materials and Methods: An atlas and reporting system of the subtalar joint was designed using a modification of Kellgren and Lawrence’s system. 50 consecutive CT scans of the subtalar joint were identified and saved along with paired plain x-rays of the foot and ankle. All investigations were anonymised. Scans were excluded if there were no plain films or there was evidence of previous trauma. Orthopaedic surgeons were asked to report on the 50 CT scans and 50 plain radiographs using the reporting protocol, commenting on two components for each investigation; the anterior and middle facets and the posterior facet of the subtalar joint. Results: In 33% of cases the facets of the subtalar joint could not be appreciated from the plain x-rays. The difference between the modalities in reported grade of degeneration of the anterior and middle facets of the subtalar joint was statistically significant (p= 0.014) but not for the posterior facet (0.726). When looking at the Spearman correlation coefficient, the anterior and middle facets had no correlation (r = − 0.067) although the posterior facet did (r = 0.029). Discussion: When looking at the posterior facet of the subtalar joint plain x-rays and CT scans give comparable results. When looking at the anterior and middle facets the information gained from the plain x-rays bears no resemblance to that gained from the CT scans. Conclusion: The plain x-ray is an inaccurate, unreliable method of investigating degenerate pathology of the subtalar joint and should be superseded, and perhaps replaced, by the CT scan

Subtalar joint stiffness is an under recognized complication of ankle fractures. We set out to objectively measure its prevalence and impact on Activities of Daily Living (ADL). Method:. 60 ankle fractures included in study. All patients had contralateral normal ankle. M:F=21:39. Average age: 36 (19 – 84). Weber: A B C. 21 27 12. 27 patients underwent ORIF (12C + 15B). 39 patients had plaster casts for between 2 and 6 weeks. (27B + 12C). Postop regimes included early mobilization and POP application (AO recommendation). Weber A (21) treated symptomatically. Examinations for study at 3/12 and 6/12 post injury. Subtalar and ankle movements were assessed by the same examiner (as per Hoppenfeld). Subjective questions about subtalar stiffness and their impact on ADL were asked. Results:. At 3/12, 56 patients (17A + 27B + 12C) had subjective and clinical impairment of subtalar movement. 32 patients (2A + 20B + 10C) had moderate to severe impairment (> 30%). At 6/12, 42 patients (9A + 23B + 10C) had subjective symptoms and clinical impairment of subtalar function. Of these, 26 (0A + 18B + 8C) had > 30% impairment vs. controls. Conclusions: Symptomatic subtalar joint stiffness with limitation of ADL is a significant sequel of ankle fractures and results in long term morbidity. This has implications in assessing functional outcome of these common injuries

Purpose: We report a series of 46 cases of subtal instability associated or not with tibiotarsal lesions treated by Castaing ligamentoplasty between 1988 and 1999. Material and methods: Preoperatively, symptoms were: instability, twisted ankle, recurrent ankle sprains, pain. A tarsal sinus syndrome was found in 39%. MRI was performed in all 46 patients and revealed ligamentary lesions in all case. Outcome was assessed with the Kitoaka score. Results: At mean 5.7 years follow-up instability had resolved in 80% of the ankles. Total pain relief was noted in 63%. Physical examination demonstrated reduced motion of the subtalar joint with inversion in 43% ranging from 50% to 70% compared with healthy side, but without significant functional impact. Radiographic signs of early-stage degeneration were found in three patients. Overall outcome was very good in 82%, fair in 11%, and poor in 7%. The index of patient satisfaction was 87%. Discussion: This series showed a correlation between body mass index greater than 26 or constitutional laxity and fair or poor results. Furthermore, longer time between the first sprain and surgical management of the residual instability led to less satisfactory final outcome. Comparison with other ligamentoplasty techniques showed similar results. Conclusion: The Castaign procedure provides results similar to other ligamentoplasty techniques. Direct repair of the subtalar ligaments should however be preferred as the first-intention procedure, reserving Castaign ligamentoplasty for cases of failed repair

To be able to assess the biomechanical and functional effects of ankle injury and disease it is necessary to characterise healthy ankle kinematics. Due to the anatomical complexity of the ankle, it is difficult to accurately measure the Tibiotalar and Subtalar joint angles using traditional marker-based motion capture techniques. Biplane Video X-ray (BVX) is an imaging technique that allows direct measurement of individual bones using high-speed, dynamic X-rays. The objective is to develop an in-vivo protocol for the hindfoot looking at the tibiotalar and subtalar joint during different activities of living. A bespoke raised walkway was manufactured to position the foot and ankle inside the field of view of the BVX system. Three healthy volunteers performed three gait and step-down trials while capturing Biplane Video X-Ray (125Hz, 1.25ms, 80kVp and 160 mA) and underwent MR imaging (Magnetom 3T Prisma, Siemens) which were manually segmented into 3D bone models (Simpleware Scan IP, Synopsis). Bone position and orientation for the Talus, Calcaneus and Tibia were calculated by manual matching of 3D Bone models to X-Rays (DSX Suite, C-Motion, Inc.). Kinematics were calculated using MATLAB (MathWorks, Inc. USA). Pilot results showed that for the subtalar joint there was greater range of motion (ROM) for Inversion and Dorsiflexion angles during stance phase of gait and reduced ROM for Internal Rotation compared with step down. For the tibiotalar joint, Gait had greater inversion and internal rotation ROM and reduced dorsiflexion ROM when compared with step down. The developed protocol successfully calculated the in-vivo kinematics of the tibiotalar and subtalar joints for different dynamic activities of daily living. These pilot results show the different kinematic profiles between two different activities of daily living. Future work will investigate translation kinematics of the two joints to fully characterise healthy kinematics

Background. RHF nail is an important tool for simultaneous ankle and subtalar joint stabilisation +/− fusion. Straight and curved RHF nails are available to use, but both seem to endanger plantar structures, especially the lateral plantar artery and nerve and Baxter's nerve. There is a paucity of literature on the structures at risk with a straight RHF nail inserted along a line bisecting the heel pad and the second toe (after Stephenson et al). In this study, plantar structures ‘at risk’ were studied in relation to a straight nail inserted as above. Methods. Re-creating real-life conditions and strictly following the recommended surgical technique with regards to the incision and guide-wire placement, we inserted an Orthosolutions Oxbridge nail into the tibia across the ankle and subtalar joints in 6 cadaveric specimens. Tissue flaps were then raised to expose the heel plantar structures and studied their relation to the inserted nail. Results. The medial plantar artery and nerve were always more than 10mm away from the medial edge of the nail, while the Baxter nerve was a mean 14mm behind. The lateral plantar nerve was a mean 7mm medial to the nail, while the artery was a mean 2.3mm away with macroscopic injury in one specimen. The other structures ‘at risk’ were the plantar fascia and small foot muscles. Conclusion. Lateral plantar artery and nerve are the most vulnerable structures during straight RHF nailing. The risk to heel plantar structures could be mitigated by making incisions longer, blunt dissection down to bone, meticulous retraction of soft tissues and placement of the protection sleeve down to bone to prevent the entrapment of plantar structures during guide-wire placement, reaming and nail insertion

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. Whereas arthroscopic arthrodesis of the ankle is commonplace and of the subtalar joint is established, reports of arthroscopic talo-navicular fusion are a rarity. Aim. To review a case series to establish if arthroscopic talo-navicular arthrodesis is a feasible surgical option. Methods. Arthroscopic decortication of the talo-navicular joint is performed via x1-2 sinus tarsi portals and x1-2 accessory talo-navicular portals using a standard arthroscope and a 4.5 barrel burr. Internal fixation is by a 5mm screw from the navicular tuberosity and x2 headless compression screws introduced under image intensification from the dorsal navicular to the talar head. Between 2004 and 2017 a consecutive series of 164 patients underwent arthroscopic hindfoot arthrodeses of which 72 involved the talo-navicular joint. Only 13 procedures were of that joint alone in unsullied feet. The medical records of these 13 patients were reviewed to assess radiological fusion, complications and improvement of pre-operative state. Results. All Talo-navicular joints were successfully decorticated. All united radiologically by a mean 4.4 months (range 3–8). There were no major complications. All patients reported improvement to their pre-operative symptoms but one patient developed lateral column pain requiring fusion. Conclusions. Arthroscopic Talo-navicular arthrodesis is technically feasible with good rates of union. Complications were rare, making the technique attractive when encountering a poor soft tissue envelope. The surgery cannot be used if bone grafting is required. Long term discomfort can arise from adjacent joints. Accurate alignment is critical

Talar body fractures are high energy intraarticular injuries that are best management by anatomical reduction and secure fixation to improve outcomes. The talus is relatively inaccessible surgically and requires extensive soft tissue dissection and/or osteotomies to gain adequate open visualisation. There are a small number of case reports on arthroscopic assisted fixation in the literature. This case series reports on the technique and early outcomes of six patients all of whom presented with significant intraarticular displacement and who were managed entirely arthroscopically. The fractures were of the main body of the talus involving the ankle and subtalar joints and all had preoperative CT scans. All six patients underwent posterior ankle and subtalar arthroscopy with cannulated screws used to stabilise the fractures after reduction. Visualisation of the fracture reduction was excellent. After 10 days in a backslab, the patients were protected in a boot and encouraged to actively move their ankles. Weight bearing was permitted once union appeared complete. There were no early complications of infection, avascular necrosis or VTE. There was one patient that had a non-clinically significant migration of a screw. Two patients were lost to follow up early due to being visitors. The mean length of follow up was 12 months in the remainder. The remaining four patients all returned to their preoperative level of activity. All had demonstrable subtalar stiffness. There was no early post-traumatic arthritis. This series represents the largest so far published. The main flaw in this report is the lack of long term follow up. While this report cannot state superiority over open techniques it is a safe, effective and acceptable technique that has significant conceptual benefits

Introduction. Tibiocalcaneal arthrodesis with a retrograde intramedullary nail is an established procedure considered as a salvage in case of severe arthritis and deformity of the ankle and subtalar joints [1]. Recently, a significant development in hindfoot arthrodesis with plates has been indicated. Therefore, the aim of this study was to compare a plate specifically developed for arthrodesis of the hindfoot with an already established nail system [2]. Method. Sixteen paired human cadaveric lower legs with removed forefoot and cut at mid-tibia were assigned to two groups for tibiocalcaneal arthrodesis using either a hindfoot arthrodesis nail or an arthrodesis plate. The specimens were tested under progressively increasing cyclic loading in dorsiflexion and plantar flexion to failure, with monitoring via motion tracking. Initial stiffness was calculated together with range of motion in dorsiflexion and plantar flexion after 200, 400, 600, 800, and 1000 cycles. Cycles to failure were evaluated based on 5° dorsiflexion failure criterion. Result. Initial stiffness in dorsiflexion, plantar flexion, varus, valgus, internal rotation and external rotation did not differ significantly between the two arthrodesis techniques (p ≥ 0.118). Range of motion in dorsiflexion and plantar flexion increased significantly between 200 and 1000 cycles (p < 0.001) and remained not significantly different between the groups (p ≥ 0.120). Cycles to failure did not differ significantly between the two techniques (p = 0.764). Conclusion. From biomechanical point of view, both tested techniques for tibiocalcaneal arthrodesis appear to be applicable. However, clinical trials and other factors, such as extent of the deformity, choice of the approach and preference of the surgeon play the main role for implant choice. Acknowledgements. This study was performed with the assistance of the AO Foundation

Tibiotalocalcaneal arthrodesis (TTCA) is a salvage procedure to functionally block the ankle and subtalar joints to treat severe ankle and hindfoot disease. Complication rates range between 20-40%, with below-knee amputation rate 1.5-19%. The heterogeneous patient cohort and indication(s) for surgery make post-operative outcomes difficult to predict. Consulting patients about potential pain and functional outcomes is difficult. When researching this area commonly, PROM data is used, less frequently functional objective measures like the 2-minute-walk-test (2MWT) are used. The aim was to compare the PROMs and objective outcomes between patients who underwent TTCA and BKA. Fifty-two patients underwent a TTCA using an intramedullary hindfoot nail. Indications for TTCA, post-traumatic OA, failed arthrodesis and malalignment. These patients were compared to 11 patients who underwent unilateral below knee amputation (BKA) due to trauma. Outcomes measures PROMs AOFAS ankle hindfoot scale and Shor-Form 36 (SF-36). Objective measures; 2MWT, Timed-up-and-go (TUG). Mean age TTCA 55.9, BKA 46.4. Average follow-up time 53 months. TTCA group had average 6.3 operations prior to arthrodesis (range 1-23). Of the TTCA group two ankles did not unite (7%), all complication rate 35%, 18% reported no pain. A significant negative correlation was demonstrated between the clinical outcome and the number of surgeries prior to the TTCA. TUG and 2MWT had significantly (p<0.05) better outcomes for the BKA group compared to TTCA. SF-36 BKA patients scored higher than the TTCA patients on physical functioning (p<0.01) and mental health (p<0.05) subscales as well as the mental component score (p<0.05). This study gives clinicians evidence about the natural history of hindfoot arthrodesis and functional outcomes from BKA. Hopefully this study will improve evidence to help patients and surgeons make decisions about expected surgical outcomes from TTCA and BKA procedures

Several emerging reports suggest an important involvement of the hindfoot alignment in the outcome of knee osteotomy. At present, studies lack a comprehensive overview. Therefore, we aimed to systematically review all biomechanical and clinical studies investigating the role of the hindfoot alignment in the setting of osteotomies around the knee. A systematic literature search was conducted on multiple databases combining “knee osteotomy” and “hindfoot/ankle alignment” search terms. Articles were screened and included according to the PRISMA guidelines. A quality assessment was conducted using the Quality Appraisal for Cadaveric Studies (QUACS) - and modified methodologic index for non-randomized studies (MINORS) scales. Three cadaveric, fourteen retrospective cohort and two case-control studies were eligible for review. Biomechanical hindfoot characteristics were positively affected (n=4), except in rigid subtalar joint (n=1) or talar tilt (n=1) deformity. Patient symptoms and/or radiographic alignment at the level of the hindfoot did also improve after knee osteotomy (n=13), except in case of a small pre-operative lateral distal tibia- and hip knee ankle (HKA) angulation or in case of a large HKA correction (>14.5°). Additionally, a pre-existent hindfoot deformity (>15.9°) was associated with undercorrection of lower limb alignment following knee osteotomy. The mean QUACS score was 61.3% (range: 46–69%) and mean MINORS score was 9.2 out of 16 (range 6–12) for non-comparative and 16.5 out of 24 (range 15–18) for comparative studies. Osteotomies performed to correct knee deformity have also an impact on biomechanical and clinical outcomes of the hindfoot. In general, these are reported to be beneficial, but several parameters were identified that are associated with newly onset – or deterioration of hindfoot symptoms following knee osteotomy. Further prospective studies are warranted to assess how diagnostic and therapeutic algorithms based on the identified criteria could be implemented to optimize the overall outcome of knee osteotomy. Remark: Aline Van Oevelen and Arne Burssens contributed equally to this work

Background. Ankle and hindfoot fusion in the presence of large bony defects represents a challenging problem. Treatment options include acute shortening and fusion or void filling with metal cages or structural allograft, which both have historically low union rates. Impaction grafting is an alternative option. Methods. A 2 centre retrospective review of consecutive series of 32 patients undergoing hindfoot fusions with impaction bone grafting of morselised femoral head allograft to fill large bony void defects was performed. Union was assessed clinically and with either plain radiography or weightbearing CT scanning. Indications included failed total ankle replacement (24 patients), talar osteonecrosis (6 patients) and fracture non-union (2 patients). Mean depth of the defect was 29 ±10.7 mm and mean maximal cross-sectional area was 15.9 ±5.8 cm. 2. Tibiotalocalcaneal (TTC) arthrodesis was performed in 24 patients, ankle arthrodesis in 7 patients and triple arthrodesis in 1 patient. Results. Mean age was 57 years (19–76 years). Mean follow-up of 22.8 ±8.3 months. 22% were smokers. There were 4 tibiotalar non-unions (12.5%), two of which were symptomatic. 10 TTC arthrodesis patients united at the tibiotalar joint but not at the subtalar joint (31.3%), but only two of these were symptomatic. The combined symptomatic non-union rate was 12.5%. Mean time to union was 9.6 ±5.9 months. One subtalar non-union patient underwent re-operation at 78 months post-operatively after failure of metalwork. Two (13%) patients developed a stress fracture above the metalwork that healed with non-operative measures. There was no bone graft collapse with all patients maintaining bone length. Conclusion. Impaction of morselised femoral head allograft can be used to fill large bony voids around the ankle and hindfoot when undertaking arthrodesis, with rapid graft incorporation and no graft collapse despite early loading. This technique offers satisfactory union outcomes without the need for shortening or synthetic cages

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. Patients undergoing total knee arthroplasty (TKA) with end-stage osteoarthritis of knee have secondary foot and ankle pathology. Some compensatory changes occur at ankle and subtalar joint secondary to malalignment and deformity at the knee joint. Purpose was to evaluate the changes in hindfoot malalignment and foot deformities in patients with advanced osteoarthritis of knee requiring TKA and effect of correction of knee deformities post TKA on foot/Ankle alignment. Methods. 61 consecutive patients with Kellgren-Lawrence grade IV osteoarthritis knee undergoing TKA were enrolled in a prospective blinded study. Demographic data, deformities at knee and ankle, hindfoot malalignment and functional outcome scores such as VAS, KSS, WOMAC scores, Foot and Ankle Disability Index (FADI) and Foot posture index (FPI) were recorded preoperatively and postoperatively at 6, 12 weeks and final follow up (range: 6–21 months; mean: 14.2months). Results. Statistically significant improvement was observed in KSS score, WOMAC score, FADI and FPI after TKA. There was improvement in ankle valgus after correction of knee varus deformity. Hind foot changes mainly occured at subtalar joint. Hallux valgus (10 patients), and Pesplanus (5 patients) were associated with advanced osteoarthritis of knee. Gait profile score and Gait deviation index improved significantly after TKA. There was increased stance phase and decreased stride length in knee osteoarthritis patients which improved after TKA. Conclusion. Hind foot malalignment with foot deformities (hind foot valgus) occur secondary to knee malalignment and deformities (varus deformity) in advanced osteoarthritis of knee which subsequently improve following TKA