The December 2024 Foot & Ankle Roundup³⁶⁰ looks at: Tibiotalar sector and lateral ankle instability; Isolated subtalar fusion and correction of progressive collapsing foot deformity; Diabetic control and postoperative complications following ankle fracture fixation; Are insoles of any benefit for plantar fasciitis?; Postoperative foot shape and patient-reported outcome following surgery for progressing collapsing foot deformity; Calcaneo-stop procedure for symptomatic flexible flatfoot in children.

Hip precautions following total hip arthroplasty (THA) limits flexion, adduction and internal rotation, yet these precautions cause unnecessary psychological stress. This study aims to assess bony and implant impingement using virtual models from actual patient's bony morphology and spinopelvic parameters to deduce whether hip precautions are necessary with precise implant positioning in the Asian population. Individualized sitting and standing sacral slope data of robotic THAs performed at two tertiary referral centers in Hong Kong was inputted into the simulation system based on patients’ pre-operative sitting and standing lumbar spine X-rays. Three-dimensional dynamic models were reconstructed using the Stryker Mako THA 4.0 software to assess bony and implant impingement both anteriorly and posteriorly, with default cup placement at 40° inclination and 20° anteversion. Femoral anteversion followed individual patient's native version. A 36mm hip ball was chosen for all cups equal or above 48mm and 32mm for those below. Anterior impingement was assessed by hip flexion and posterior impingement was assessed by hip extension. 113 patients were included. At neutral rotation and adduction, no patients had anterior implant impingement at hip flexion of 100°. 1.7% had impingement at 110°, 3.5% had impingement at 120°, 9.7% had impingement at 130°. With 20° of internal rotation and adduction, 0.8% had anterior implant impingement at hip flexion of 90°, 7.1% had impingement at 100° and 18.5% had impingement at 110°. With the hip externally rotated by 20°, 0.8% of patients had posterior implant impingement, and 8.8% bony impingement at 0° extension. With enabling technology allowing accurate component positioning, hip precautions without limiting forward flexion in neutral position is safe given precise implant positioning and adequate osteophyte removal. Patients should only be cautioned about combined internal rotation, adduction with flexion

Aims

Precise implant positioning, tailored to individual spinopelvic biomechanics and phenotype, is paramount for stability in total hip arthroplasty (THA). Despite a few studies on instability prediction, there is a notable gap in research utilizing artificial intelligence (AI). The objective of our pilot study was to evaluate the feasibility of developing an AI algorithm tailored to individual spinopelvic mechanics and patient phenotype for predicting impingement.

The June 2024 Foot & Ankle Roundup³⁶⁰ looks at: First MTPJ fusion in young versus old patients; Minimally invasive calcaneum Zadek osteotomy and the effect of sequential burr passes; Comparison between Achilles tendon reinsertion and dorsal closing wedge calcaneal osteotomy for the treatment of insertional Achilles tendinopathy; Revision ankle arthroplasty – is it worthwhile?; Tibiotalocalcaneal arthrodesis or below-knee amputation – salvage or sacrifice?; Fusion or replacement for hallux rigidus?.

Aims. The purpose of this study was to evaluate the mid-term outcomes of autologous matrix-induced chondrogenesis (AMIC) for the treatment of larger cartilage lesions and deformity correction in hips suffering from symptomatic femoroacetabular impingement (FAI). Methods. This single-centre study focused on a cohort of 24 patients with cam- or pincer-type FAI, full-thickness femoral or acetabular chondral lesions, or osteochondral lesions ≥ 2 cm. 2. , who underwent surgical hip dislocation for FAI correction in combination with AMIC between March 2009 and February 2016. Baseline data were retrospectively obtained from patient files. Mid-term outcomes were prospectively collected at a follow-up in 2020: cartilage repair tissue quality was evaluated by MRI using the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score. Patient-reported outcome measures (PROMs) included the Oxford Hip Score (OHS) and Core Outcome Measure Index (COMI). Clinical examination included range of motion, impingement tests, and pain. Results. A total of 12 hips from 11 patients were included (ten males, one female, mean age 26.8 years (SD 5.0), mean follow-up 6.2 years (SD 5.2 months)). The mean postoperative MOCART score was 66.3 (SD 16.3). None of the patients required conversion to total hip arthroplasty. Two patients had anterior impingement. External hip rotation was moderately limited in four patients. There was a correlation between MOCART and follow-up time (r. s. = -0.61; p = 0.035), but not with initial cartilage damage, age, BMI, or imaging time delay before surgery. PROMs improved significantly: OHS from 37.4 to 42.7 (p = 0.014) and COMI from 4.1 to 1.6 (p = 0.025). There was no correlation between MOCART and PROMs. Conclusion. Based on the reported mid-term results, we consider AMIC as an encouraging treatment option for large cartilage lesions of the hip. Nonetheless, the clinical evidence of AMIC in FAI patients remains to be determined, ideally in the context of randomized controlled trials. Cite this article: Bone Joint J 2024;106-B(5 Supple B):32–39

Aims

Dual-mobility (DM) components are increasingly used to prevent and treat dislocation after total hip arthroplasty (THA). Intraprosthetic dissociation (IPD) is a rare complication of DM that is believed to have decreased with contemporary implants. This study aimed to report incidence, treatment, and outcomes of contemporary DM IPD.

Aims. Mechanical impingement of the iliopsoas (IP) tendon accounts for 2% to 6% of persistent postoperative pain after total hip arthroplasty (THA). The most common initiator is anterior acetabular component protrusion, where the anterior margin is not covered by anterior acetabular wall. A CT scan can be used to identify and measure this overhang; however, no threshold exists for determining symptomatic anterior IP impingement due to overhang. A case-control study was conducted in which CT scan measurements were used to define a threshold that differentiates patients with IP impingement from asymptomatic patients after THA. Methods. We analyzed the CT scans of 622 patients (758 THAs) between May 2011 and May 2020. From this population, we identified 136 patients with symptoms suggestive of IP impingement. Among them, six were subsequently excluded: three because the diagnosis was refuted intraoperatively, and three because they had another obvious cause of impingement, leaving 130 hips (130 patients) in the study (impingement) group. They were matched to a control group of 138 asymptomatic hips (138 patients) after THA. The anterior acetabular component overhang was measured on an axial CT slice based on anatomical landmarks (orthogonal to the pelvic axis). Results. The impingement group had a median overhang of 8 mm (interquartile range (IQR) 5 to 11) versus 0 mm (IQR 0 to 4) for the control group (p < 0.001). Using receiver operating characteristic curves, an overhang threshold of 4 mm was best correlated with a diagnosis of impingement (sensitivity 79%, specificity 85%; positive predictive value 75%, negative predictive value 85%). Conclusion. Pain after THA related to IP impingement can be reasonably linked to acetabular overhang if it exceeds 4 mm on a CT scan. Below this threshold, it seems logical to look for another cause of IP irritation or another reason for the pain after THA before concluding that impingement is present. Cite this article: Bone Joint J 2024;106-B(3 Supple A):97–103

Aims

The aim of this study was to identify the optimal lip position for total hip arthroplasties (THAs) using a lipped liner. There is a lack of consensus on the optimal position, with substantial variability in surgeon practice.

Aims

The risk factors for abnormal spinopelvic mobility (SPM), defined as an anterior rotation of the spinopelvic tilt (∆SPT) ≥ 20° in a flexed-seated position, have been described. The implication of pelvic incidence (PI) is unclear, and the concept of lumbar lordosis (LL) based on anatomical limits may be erroneous. The distribution of LL, including a unusual shape in patients with a high lordosis, a low pelvic incidence, and an anteverted pelvis seems more relevant.

The August 2023 Foot & Ankle Roundup³⁶⁰ looks at: Achilles tendon rupture: surgery or conservative treatment for the high-demand patient?; First ray amputation in diabetic patients; Survival of ankle arthroplasty in the UK; First metatarsophalangeal joint fusion and flat foot correction; Intra-articular corticosteroid injections with or without hyaluronic acid in the management of subtalar osteoarthritis; Factors associated with nonunion of post-traumatic subtalar arthrodesis; The Mayo Prosthetic Joint Infection Risk Score for total ankle arthroplasty.

Mechanical irritation or impingement of the iliopsoas tendon accounts for 2–6% of persistent postoperative pain cases after total hip arthroplasty (THA). The most common trigger is anterior cup overhang. CT-scan can be used to identify and measure this overhang; however, no threshold exists for symptomatic anterior iliopsoas impingement. We conducted a case–control study in which CT-scan was used to define a threshold that differentiates patients with iliopsoas impingement from asymptomatic patients after THA. We analyzed the CT-scans of 622 patients (758 CT-scans) between 2011 and 2020. Out of this population we identified 136 patients with symptoms suggestive of iliopsoas impingement. Among them, 6 were subsequently excluded: three because the diagnosis was reestablished intra-operatively (one metallosis, two anterior instability related to posterior prosthetic impingement) and three because they had another obvious cause of impingement (one protruding screw, one protruding cement plug, one stem collar), leaving 130 patients in the study (impingement) group. They were matched to a control group of 138 patients who were asymptomatic after THA. The anterior cup overhang (anterior margin of cup not covered by anterior wall) was measured by an observer (without knowledge of the clinical status) on an axial CT slice based on anatomical landmarks (orthogonal to pelvic axis). The impingement group had a median overhang of 8 mm [IQR: 5 to 11] versus 0 mm [IQR: 0 to 4] for the control group (p<.001). Using ROC curves, an overhang threshold of 4 mm was best correlated with a diagnosis of impingement (sensitivity 79%, specificity 85%, PPV = 75%, NPV = 85%). Pain after THA related to iliopsoas impingement can be reasonably linked to acetabular overhang if it exceeds 4 mm on a CT scan. Below this threshold, it seems logical to look for another cause of iliopsoas irritation or another reason for the pain after THA before concluding impingement is present

Aims

This systematic review aimed to summarize the full range of complications reported following ankle arthroscopy and the frequency at which they occur.

Long femoral nails for neck of femur fractures and prophylactic fixation have a risk of anterior cortex perforation. Previous studies have demonstrated the radius of curvature (ROC) of a femoral nail influencing the finishing point of a nail and the risk of anterior cortex perforation. This study aims to calculate a patients femoral ROC using preoperative XR and CT and therefore nail finishing position. We conducted a retrospective study review of patients with long femoral cephalomedullary nailing for proximal femur fractures (OTA/AO 31(A) and OTA/AO 32) or impending pathological fractures at a level 1 trauma centre between January 1, 2015 and December 31, 2020 with both full length lateral X-ray and CT imaging. Femoral ROC was calculated on both imaging modalities. Outcomes measured including nail finishing position, anterior cortex encroachment and impingement. The mean femoral ROC was 1026mm on CT and 1244mm on XR. CT femoral ROC strongly correlated with nail finishing point with a spearmans coefficient of 0.77. Additionally, femurs with a ROC <1000mm were associated with a higher risk of anterior encroachment (OR 6.12) and femurs with a ROC <900mm were associated with a higher risk of anterior cortex impingement (OR 6.47). To our knowledge this is the first study to compare a measured femoral ROC to nail finishing position. The use of CT to measure femoral ROC and to a lesser extent XR was able to predict both nail finishing position and risk of anterior cortex encroachment. Preoperative XRs and CTs were able to identify patients with a small femoral ROC. This predicted patients at risk of anterior cortex impingement, anterior cortex encroachment and nail finishing position. We may be able to select femoral nails that resemble the native femoral ROC and mitigate the risk of anterior cortex perforation

Aims. Femoroacetabular impingement (FAI) patients report exacerbation of hip pain in deep flexion. However, the exact impingement location in deep flexion is unknown. The aim was to investigate impingement-free maximal flexion, impingement location, and if cam deformity causes hip impingement in flexion in FAI patients. Methods. A retrospective study involving 24 patients (37 hips) with FAI and femoral retroversion (femoral version (FV) < 5° per Murphy method) was performed. All patients were symptomatic (mean age 28 years (SD 9)) and had anterior hip/groin pain and a positive anterior impingement test. Cam- and pincer-type subgroups were analyzed. Patients were compared to an asymptomatic control group (26 hips). All patients underwent pelvic CT scans to generate personalized CT-based 3D models and validated software for patient-specific impingement simulation (equidistant method). Results. Mean impingement-free flexion of patients with mixed-type FAI (110° (SD 8°)) and patients with pincer-type FAI (112° (SD 8°)) was significantly (p < 0.001) lower compared to the control group (125° (SD 13°)). The frequency of extra-articular subspine impingement was significantly (p < 0.001) increased in patients with pincer-type FAI (57%) compared to cam-type FAI (22%) in 125° flexion. Bony impingement in maximal flexion was located anterior-inferior at femoral four and five o’clock position in patients with cam-type FAI (63% (10 of 16 hips) and 37% (6 of 10 hips)), and did not involve the cam deformity. The cam deformity did not cause impingement in maximal flexion. Conclusion. Femoral impingement in maximal flexion was located anterior-inferior distal to the cam deformity. This differs to previous studies, a finding which could be important for FAI patients in order to avoid exacerbation of hip pain in deep flexion (e.g. during squats) and for hip arthroscopy (hip-preservation surgery) for planning of bone resection. Hip impingement in flexion has implications for daily activities (e.g. putting on shoes), sports, and sex. Cite this article: Bone Joint Res 2023;12(1):22–32

Aims

Iliopsoas impingement occurs in 4% to 30% of patients after undergoing total hip arthroplasty (THA). Despite a relatively high incidence, there are few attempts at modelling impingement between the iliopsoas and acetabular component, and no attempts at modelling this in a representative cohort of subjects. The purpose of this study was to develop a novel computational model for quantifying the impingement between the iliopsoas and acetabular component and validate its utility in a case-controlled investigation.

The 10 year survivorship of THR is generally over 95%. However, the incidence of revision is usually higher in year one. The most common reason being dislocation which at least in part is driven by inadequate range of motion (ROM) leading to impingement, subluxation and ultimately dislocation which is more frequently posterior. ROM is affected by patient activity, bone and component geometry, and component placement. To reduce the incidence of dislocation, supported by registry data, there has been an increase in the use of so-called ‘lipped’ liners. Whilst this increases joint stability, the theoretical ROM is reduced. The aim of this study was to investigate the effect of lip placement on impingement. A rigid body geometric model was incorporated into a CT scan hemi-pelvis and femur, with a clinically available THR virtually implanted. Kinematic activity data associated with dislocation was applied, comprising of five posterior and two anterior dislocation risk activities, resulting from anterior and posterior impingement respectively. Cup inclination and anteversion was varied (30°-70°, 0°-50° respectively) to simulate extremes of clinical outcomes. The apex position of a ‘lipped’ liner was rotated from the superior position, anteriorly and posteriorly in steps of 45°. Incidence and location of implant and bone impingement was recorded in 5346 cases generated. A liner with the lip placed superior increased the occurrence of implant-implant impingement compared with a neutral liner. Rotation of the lip from superior reduced this incidence. This effect was more marked with posterior rotation which after 90° reduced anterior impingement to levels similar to a neutral liner. Complete inversion of the lipped liner reduced impingement, but this and anterior rotation both negate its function – additional stability. This study comprises one bone geometry and component design and one set of activity profiles. Nevertheless, it indicates that appropriate lip placement can minimise the likelihood of impingement for a range of daily activities whilst still providing additional joint stability

Aims

Pelvic incidence (PI) is a position-independent spinopelvic parameter traditionally used by spinal surgeons to determine spinal alignment. Its relevance to the arthroplasty surgeon in assessing patient risk for total hip arthroplasty (THA) instability preoperatively is unclear. This study was undertaken to investigate the significance of PI relative to other spinopelvic parameter risk factors for instability to help guide its clinical application.

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This study aimed to investigate the relationship between changes in patellar height and clinical outcomes at a mean follow-up of 7.7 years (5 to 10) after fixed-bearing posterior-stabilized total knee arthroplasty (PS-TKA).

Aims

Spinopelvic mobility plays an important role in functional acetabular component position following total hip arthroplasty (THA). The primary aim of this study was to determine if spinopelvic hypermobility persists or resolves following THA. Our second aim was to identify patient demographic or radiological factors associated with hypermobility and resolution of hypermobility after THA.