Aims. Total knee arthroplasty (TKA) may provoke ankle symptoms. The aim of this study was to validate the impact of the preoperative mechanical tibiofemoral angle (mTFA), the talar tilt (TT) on ankle symptoms after TKA, and assess changes in the range of motion (ROM) of the subtalar joint, foot posture, and ankle laxity. Methods. Patients who underwent TKA from September 2020 to September 2021 were prospectively included. Inclusion criteria were primary end-stage osteoarthritis (Kellgren-Lawrence stage IV) of the knee. Exclusion criteria were missed follow-up visit, post-traumatic pathologies of the foot, and neurological disorders. Radiological angles measured included the mTFA, hindfoot alignment view angle, and TT. The Foot Function Index (FFI) score was assessed. Gait analyses were conducted to measure mediolateral changes of the gait line and ankle laxity was tested using an ankle arthrometer. All parameters were acquired one week pre- and three months postoperatively. Results. A total of 69 patients (varus n = 45; valgus n = 24) underwent TKA and completed the postoperative follow-up visit. Of these, 16 patients (23.2%) reported the onset or progression of ankle symptoms. Varus patients with increased ankle symptoms after TKA had a significantly higher pre- and postoperative TT. Valgus patients with ankle symptoms after TKA showed a pathologically lateralized gait line which could not be corrected through TKA. Patients who reported increased ankle pain neither had a decreased ROM of the subtalar joint nor increased ankle laxity following TKA. The preoperative mTFA did not correlate with the postoperative FFI (r = 0.037; p = 0.759). Conclusion. Approximately one-quarter of the patients developed ankle pain after TKA. If patients complain about ankle symptoms after TKA, standing radiographs of the ankle and a gait analysis could help in detecting a malaligned TT or a pathological gait. Cite this article: Bone Joint J 2023;105-B(11):1159–1167

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

Aims. The pathogenesis of intraneural ganglion cysts is controversial. Recent reports in the literature described medial plantar intraneural ganglion cysts (mIGC) with articular branches to subtalar joints. The aim of the current study was to provide further support for the principles underlying the articular theory, and to explain the successes and failures of treatment of mICGs. Patients and Methods. Between 2006 and 2017, five patients with five mICGs were retrospectively reviewed. There were five men with a mean age of 50.2 years (33 to 68) and a mean follow-up of 3.8 years (0.8 to 6). Case history, physical examination, imaging, and intraoperative findings were reviewed. The outcomes of interest were ultrasound and/or MRI features of mICG, as well as the clinical outcomes. Results. The five intraneural cysts followed the principles of the unifying articular theory. Connection to the posterior subtalar joint (pSTJ) was identified or suspected in four patients. Re-evaluation of preoperative MRI demonstrated a degenerative pSTJ and denervation changes in the abductor hallucis in all patients. Cyst excision with resection of the articular branch (four), cyst incision and drainage (one), and percutaneous aspiration/steroid injection (two) were performed. Removing the connection to the pSTJ prevented recurrence of mIGC, whereas medial plantar nerves remained cystic and symptomatic when resection of the communicating articular branch was not performed. Conclusion. Our findings support a standardized treatment algorithm for mIGC in the presence of degenerative disease at the pSTJ. By understanding the pathoanatomic mechanism for every cyst, we can improve treatment that must address the articular branch to avoid the recurrence of intraneural ganglion cysts, as well as the degenerative pSTJ to avoid extraneural cyst formation or recurrence. Cite this article: Bone Joint J 2018;100-B:183–9

The subtalar joint is not easy to visualise by standard radiographic methods. Several projections are described including medial and lateral oblique axial views to demonstrate the three compartments of the joint. It is suggested that when visualisation of the subtalar joint is required these views should be routine. Various conditions affecting the subtalar joint and their demonstration by these oblique axial views are discussed

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

We have developed a method of measuring anterior displacement of the calcaneus on the talus in instability of the subtalar joint and have used the technique to demonstrate anterior instability in 50 patients (72 feet) showing a positive drawer sign. The angle of the posterior facet of the talus was also measured to assess the bony configuration. Our patients with subtalar joint instability could be divided into three categories. The first group had a history of trauma leading to ankle instability (26 cases), the second showed generalised joint laxity (10 cases) and the third were young females with a history of chronic stress on the foot and a poor bony block (14 cases). Satisfactory results were obtained by treating the instability with a brace or by reconstruction of the interosseous talocalcaneal ligament

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

1 . A small series of fractures of the calcaneum with distortion of the subtalar joint has been reviewed. 2. All were treated by subtalar fusion, in most as part of the primary treatment. 3. In all patients the subtalar joint fused by bone without post-operative plaster immobilisation. 4. Plaster immobilisation is not only unnecessary, it is undesirable. 5. Heavy work, including work on ladders and scaffolding, can be undertaken after subtalar fusion

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

Thirty-six patients with 39 fresh fractures of the calcaneus were investigated by standard radiography and by computerised tomography. It was found that the size and disposition of the fracture fragments and the degree of involvement of the posterior facet of the subtalar joint were more clearly shown by CT scanning. We recommend this technique for assessment and particularly for pre-operative planning

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

1. A modification of the Grice extra-articular subtalar arthrodesis is described.

2. The results of this operation are presented.

1. A simple method of subtalar fusion, suitable for use in children, is described.

2. Although it is intended to provide stability for some years until a complete subtalar fusion can be carried out, further operation may not be necessary.

3. Its use is not advocated over the age of eleven or twelve.

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

Aims. No randomized comparative study has compared the extensile lateral approach (ELA) and sinus tarsi approach (STA) for Sanders type 2 calcaneal fractures. This randomized comparative study was conducted to confirm whether the STA was prone to fewer wound complications than the ELA. Methods. Between August 2013 and August 2018, 64 patients with Sanders type 2 calcaneus fractures were randomly assigned to receive surgical treatment by the ELA (32 patients) and STA (32 patients). The primary outcome was development of wound complications. The secondary outcomes were postoperative complications, pain scored of a visual analogue scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) score, 36-item Short Form health survey, operative duration, subtalar joint range of motion (ROM), Böhler’s angle and calcaneal width, and posterior facet reduction. Results. Although four patients (12.5%) in the ELA groups and none in the STA group experienced complications, the difference was not statistically significant (p = 0.113). VAS and AOFAS score were significantly better in the STA group than in the ELA group at six months (p = 0.017 and p = 0.021), but not at 12 months (p = 0.096 and p = 0.200) after surgery. The operation time was significantly shorter in the STA group than in the ELA group (p < 0.001). The subtalar joint ROM was significantly better in the STA group (p = 0.015). Assessment of the amount of postoperative reduction compared with the uninjured limb showed significant restoration of calcaneal width in the ELA group compared with that in the STA group (p < 0.001). Conclusion. The ELA group showed higher frequency of wound complications than the STA group for Sanders type 2 calcaneal fractures even though this was not statistically significant. Cite this article: Bone Joint J 2021;103-B(2):286–293

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