Aims. This systematic review aims to identify 3D predictors derived from biplanar reconstruction, and to describe current methods for improving curve prediction in patients with mild adolescent idiopathic scoliosis. Methods. A comprehensive search was conducted by three independent investigators on MEDLINE, PubMed, Web of Science, and Cochrane Library. Search terms included “adolescent idiopathic scoliosis”,“3D”, and “progression”. The inclusion and exclusion criteria were carefully defined to include clinical studies. Risk of bias was assessed with the Quality in Prognostic Studies tool (QUIPS) and Appraisal tool for Cross-Sectional Studies (AXIS), and level of evidence for each predictor was rated with the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) approach. In all, 915 publications were identified, with 377 articles subjected to full-text screening; overall, 31 articles were included. Results. Torsion index (TI) and apical vertebral rotation (AVR) were identified as accurate predictors of curve progression in early visits. Initial TI > 3.7° and AVR > 5.8° were predictive of curve progression. Thoracic hypokyphosis was inconsistently observed in progressive curves with weak evidence. While sagittal wedging was observed in mild curves, there is insufficient evidence for its correlation with curve progression. In curves with initial Cobb angle < 25°, Cobb angle was a poor predictor for future curve progression. Prediction accuracy was improved by incorporating serial reconstructions in stepwise layers. However, a lack of post-hoc analysis was identified in studies involving geometrical models. Conclusion. For patients with mild curves, TI and AVR were identified as predictors of curve progression, with TI > 3.7° and AVR > 5.8° found to be important thresholds. Cobb angle acts as a poor predictor in mild curves, and more investigations are required to assess thoracic kyphosis and wedging as predictors. Cumulative reconstruction of radiographs improves prediction accuracy. Comprehensive analysis between progressive and non-progressive curves is recommended to extract meaningful thresholds for clinical prognostication. Cite this article: Bone Jt Open 2024;5(3):243–251

Aims. The transepicondylar axis is a well-established reference for the determination of femoral component rotation in total knee arthroplasty (TKA). However, when severe bone loss is present in the femoral condyles, rotational alignment can be more complicated. There is a lack of validated landmarks in the supracondylar region of the distal femur. Therefore, the aim of this study was to analyze the correlation between the surgical transepicondylar axis (sTEA) and the suggested dorsal cortex line (DCL) in the coronal plane and the inter- and intraobserver reliability of its CT scan measurement. Methods. A total of 75 randomly selected CT scans were measured by three experienced surgeons independently. The DCL was defined in the coronal plane as a tangent to the dorsal femoral cortex located 75 mm above the joint line in the frontal plane. The difference between sTEA and DCL was calculated. Descriptive statistics and angulation correlations were generated for the sTEA and DCL, as well as for the distribution of measurement error for intra- and inter-rater reliability. Results. The external rotation of the DCL to the sTEA was a mean of 9.47° (SD 3.06°), and a median of 9.2° (IQR 7.45° to 11.60°), with a minimum value of 1.7° and maximum of 16.3°. The measurements of the DCL demonstrated very good to excellent test-retest and inter-rater reliability coefficients (intraclass correlation coefficient 0.80 to 0.99). Conclusion. This study reveals a correlation between the sTEA and the DCL. Overall, 10° of external rotation of the dorsal femoral cortical bone to the sTEA may serve as a reliable landmark for initial position of the femoral component. Surgeons should be aware that there are outliers in this study in up to 17% of the measurements, which potentially could result in deviations of femoral component rotation. Cite this article: Bone Jt Open 2024;5(12):1067–1071

Aims. Hip arthroplasty aims to accurately recreate joint biomechanics. Considerable attention has been paid to vertical and horizontal offset, but femoral head centre in the anteroposterior (AP) plane has received little attention. This study investigates the accuracy of restoration of joint centre of rotation in the AP plane. Methods. Postoperative CT scans of 40 patients who underwent unilateral uncemented total hip arthroplasty were analyzed. Anteroposterior offset (APO) and femoral anteversion were measured on both the operated and non-operated sides. Sagittal tilt of the femoral stem was also measured. APO measured on axial slices was defined as the perpendicular distance between a line drawn from the anterior most point of the proximal femur (anterior reference line) to the centre of the femoral head. The anterior reference line was made parallel to the posterior condylar axis of the knee to correct for rotation. Results. Overall, 26/40 hips had a centre of rotation displaced posteriorly compared to the contralateral hip, increasing to 33/40 once corrected for sagittal tilt, with a mean posterior displacement of 7 mm. Linear regression analysis indicated that stem anteversion needed to be increased by 10.8° to recreate the head centre in the AP plane. Merely matching the native version would result in a 12 mm posterior displacement. Conclusion. This study demonstrates the significant incidence of posterior displacement of the head centre in uncemented hip arthroplasty. Effects of such displacement include a reduction in impingement free range of motion, potential alterations in muscle force vectors and lever arms, and impaired proprioception due to muscle fibre reorientation. Cite this article: Bone Joint Res 2022;11(3):180–188

Aims. The extensive variation in axial rotation of tibial components can lead to coronal plane malalignment. We analyzed the change in coronal alignment induced by tray malrotation. Methods. We constructed a computer model of knee arthroplasty and used a virtual cutting guide to cut the tibia at 90° to the coronal plane. The virtual guide was rotated axially (15° medial to 15° lateral) and with posterior slopes (0° to 7°). To assess the effect of axial malrotation, we measured the coronal plane alignment of a tibial tray that was axially rotated (25° internal to 15° external), as viewed on a standard anteroposterior (AP) radiograph. Results. Axial rotation of the cutting guide induced a varus-valgus malalignment up to 1.8° (for 15° of axial rotation combined with 7° of posterior slope). Axial malrotation of tibial tray induced a substantially higher risk of coronal plane malalignment ranging from 1.9° valgus with 15° external rotation, to over 3° varus with 25° of internal rotation. Coronal alignment of the tibial cut changed by 0.07° per degree of axial rotation and 0.22° per degree of posterior slope (linear regression, R. 2. > 0.99). Conclusion. While the effect of axial malalignment has been studied, the impact on coronal alignment is not known. Our results indicate that the direction of the cutting guide and malalignment in axial rotation alter coronal plane alignment and can increase the incidence of outliers. Cite this article: Bone Joint J 2020;102-B(6 Supple A):43–48

Aims. Hip arthroplasty does not always restore normal anatomy. This is due to inaccurate surgery or lack of stem sizes. We evaluated the aptitude of four total hip arthroplasty systems to restore an anatomical and medialized hip rotation centre. Methods. Using 3D templating software in 49 CT scans of non-deformed femora, we virtually implanted: 1) small uncemented calcar-guided stems with two offset options (Optimys, Mathys), 2) uncemented straight stems with two offset options (Summit, DePuy Synthes), 3) cemented undersized stems (Exeter philosophy) with three offset options (CPT, ZimmerBiomet), and 4) cemented line-to-line stems (Kerboul philosophy) with proportional offsets (Centris, Mathys). We measured the distance between the templated and the anatomical and 5 mm medialized hip rotation centre. Results. Both rotation centres could be restored within 5 mm in 94% and 92% of cases, respectively. The cemented undersized stem performed best, combining freedom of stem positioning and a large offset range. The uncemented straight stem performed well because of its large and well-chosen offset range, and despite the need for cortical bone contact limiting stem positioning. The cemented line-to-line stem performed less well due to a small range of sizes and offsets. The uncemented calcar-guided stem performed worst, despite 24 sizes and a large and well-chosen offset range. This was attributed to the calcar curvature restricting the stem insertion depth along the femoral axis. Conclusion. In the majority of non-deformed femora, leg length, offset, and anteversion can be restored accurately with non-modular stems during 3D templating. Failure to restore hip biomechanics is mostly due to surgical inaccuracy. Small calcar guided stems offer no advantage to restore hip biomechanics compared to more traditional designs. Cite this article: Bone Jt Open 2021;2(7):476–485

Aims. The objective of this study was to present the outcomes of rotational acetabular osteotomy (RAO) over a 30-year period for osteoarthritis (OA) secondary to dysplasia of the hip in pre- or early-stage OA. Methods. Between September 1987 and December 1994, we provided treatment to 47 patients (55 hips) with RAO for the management of pre- or early-stage OA due to developmental hip dysplasia. Of those, eight patients (11 hips) with pre-OA (follow-up rate 79%) and 27 patients (32 hips) with early-stage OA (follow-up rate 78%), totalling 35 patients (43 hips) (follow-up rate 78%), were available at a minimum of 28 years after surgery. Results. In the pre-OA group, the mean Merle d'Aubigné score improved significantly from 14.5 points (SD 0.7) preoperatively to 17.4 points at final follow-up (SD 1.2; p = 0.004) and in the early-stage group, the mean score did not improve significantly from 14.0 (SD 0.3) to 14.6 (SD 2.4; p = 0.280). Radiologically, the centre-edge angle, acetabular roof angle, and head lateralization index were significantly improved postoperatively in both groups. Radiological progression of OA was observed in two patients (two hips) in the pre-OA group and 17 patients (18 hips) in the early-stage group. Kaplan-Meier survival analysis, with radiological progression of OA as the primary outcome, projected a 30-year survival rate of 81.8% (95% confidence interval (CI) 0.59 to 1.00) for the pre-OA group and 42.2% (95% CI 0.244 to 0.600) for the early-stage group. In all cases, the overall survival rate stood at 51.5% (95% CI 0.365 to 0.674) over a 30-year period, and when the endpoint was conversion to total hip arthroplasty, the survival rate was 74.0% (95% CI 0.608 to 0.873). Conclusion. For younger patients with pre-OA, joint preservation of over 30 years can be expected after RAO. Cite this article: Bone Joint J 2024;106-B(5 Supple B):25–31

Aims. The effect of pelvic tilt (PT) and sagittal balance in hips with pincer-type femoroacetabular impingement (FAI) with acetabular retroversion (AR) is controversial. It is unclear if patients with AR have a rotational abnormality of the iliac wing. Therefore, we asked: are parameters for sagittal balance, and is rotation of the iliac wing, different in patients with AR compared to a control group?; and is there a correlation between iliac rotation and acetabular version?. Methods. A retrospective, review board-approved, controlled study was performed including 120 hips in 86 consecutive patients with symptomatic FAI or hip dysplasia. Pelvic CT scans were reviewed to calculate parameters for sagittal balance (pelvic incidence (PI), PT, and sacral slope), anterior pelvic plane angle, pelvic inclination, and external rotation of the iliac wing and were compared to a control group (48 hips). The 120 hips were allocated to the following groups: AR (41 hips), hip dysplasia (47 hips) and cam FAI with normal acetabular morphology (32 hips). Subgroups of total AR (15 hips) and high acetabular anteversion (20 hips) were analyzed. Statistical analysis was performed using analysis of variance with Bonferroni correction. Results. PI and PT were significantly decreased comparing AR (PI 42° (SD 10°), PT 4° (SD 5°)) with dysplastic hips (PI 55° (SD 12°), PT 10° (SD 6°)) and with the control group (PI 51° (SD 9°) and PT 13° (SD 7°)) (p < 0.001). External rotation of the iliac wing was significantly increased comparing AR (29° (SD 4°)) with dysplastic hips (20°(SD 5°)) and with the control group (25° (SD 5°)) (p < 0.001). Correlation between external rotation of the iliac wing and acetabular version was significant and strong (r = 0.81; p < 0.001). Correlation between PT and acetabular version was significant and moderate (r = 0.58; p < 0.001). Conclusion. These findings could contribute to a better understanding of hip pain in a sitting position and extra-articular subspine FAI of patients with AR. These patients have increased iliac external rotation, a rotational abnormality of the iliac wing. This has implications for surgical therapy with hip arthroscopy and acetabular rim trimming or anteverting periacetabular osteotomy (PAO). Cite this article: Bone Jt Open 2021;2(10):813–824

Aims. The aim of this study was to review the current evidence surrounding curve type and morphology on curve progression risk in adolescent idiopathic scoliosis (AIS). Methods. A comprehensive search was conducted by two independent reviewers on PubMed, Embase, Medline, and Web of Science to obtain all published information on morphological predictors of AIS progression. Search items included ‘adolescent idiopathic scoliosis’, ‘progression’, and ‘imaging’. The inclusion and exclusion criteria were carefully defined. Risk of bias of studies was assessed with the Quality in Prognostic Studies tool, and level of evidence for each predictor was rated with the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. In all, 6,286 publications were identified with 3,598 being subjected to secondary scrutiny. Ultimately, 26 publications (25 datasets) were included in this review. Results. For unbraced patients, high and moderate evidence was found for Cobb angle and curve type as predictors, respectively. Initial Cobb angle > 25° and thoracic curves were predictive of curve progression. For braced patients, flexibility < 28% and limited in-brace correction were factors predictive of progression with high and moderate evidence, respectively. Thoracic curves, high apical vertebral rotation, large rib vertebra angle difference, small rib vertebra angle on the convex side, and low pelvic tilt had weak evidence as predictors of curve progression. Conclusion. For curve progression, strong and consistent evidence is found for Cobb angle, curve type, flexibility, and correction rate. Cobb angle > 25° and flexibility < 28% are found to be important thresholds to guide clinical prognostication. Despite the low evidence, apical vertebral rotation, rib morphology, and pelvic tilt may be promising factors. Cite this article: Bone Joint J 2022;104-B(4):424–432

We studied the knees of 11 volunteers using RSA during a step-up exercise requiring extension while weight-bearing from 50° to 0°. The findings on weight-bearing flexion with and without external rotation of the tibia based on MRI were confirmed

Aims. The aims of this study were to determine the change in the sagittal alignment of the pelvis and the associated impact on acetabular component position at one-year follow-up after total hip arthroplasty (THA). Methods. This study represents the one-year follow-up of a previous short-term study at our institution. Using the patient population from our prior study, the radiological pelvic ratio was assessed in 91 patients undergoing THA, of whom 50 were available for follow-up of at least one year (median 1.5; interquartile range (IQR) 1.1 to 2.0). Anteroposterior radiographs of the pelvis were obtained in the standing position preoperatively and at one year postoperatively. Pelvic ratio was defined as the ratio between the vertical distance from the inferior sacroiliac (SI) joints to the superior pubic symphysis and the horizontal distance between the inferior SI joints. Apparent acetabular component position changes were determined from the change in pelvic ratio. A change of at least 5° was considered clinically meaningful. Results. Pelvic ratio decreased (posterior tilt) in 54.0% (27) of cases, did not change significantly in 34.0% (17) of cases, and increased (anterior tilt) in 12.0% (6) of cases when comparing preoperative to one-year postoperative radiographs. This would correspond with 5° to 10° of abduction error in 22.0% of cases and > 10° of error in 6.0%. Likewise, this would correspond with 5° to 10° of version error in 22.0% of cases and > 10° of error in 44.0%. Conclusion. Pelvic sagittal alignment is dynamic and variable after THA, and these changes persist to the one-year postoperative period, altering the orientation of the acetabular component. Surgeons who individualize the acetabular component placement based on preoperative functional radiographs should consider that the rotation of the pelvis (and thus the component version and inclination) changes one year postoperatively. Cite this article: Bone Joint J 2020;102-B(7 Supple B):47–51

Objectives. Throughout the 20th Century, it has been postulated that the knee moves on the basis of a four-bar link mechanism composed of the cruciate ligaments, the femur and the tibia. As a consequence, the femur has been thought to roll back with flexion, and total knee arthroplasty (TKA) prostheses have been designed on this basis. Recent work, however, has proposed that at a position of between 0° and 120° the medial femoral condyle does not move anteroposteriorly whereas the lateral femoral condyle tends, but is not obliged, to roll back – a combination of movements which equates to tibial internal/ femoral external rotation with flexion. The aim of this paper was to assess if the articular geometry of the GMK Sphere TKA could recreate the natural knee movements in situ/in vivo. Methods. The pattern of knee movement was studied in 15 patients (six male: nine female; one male with bilateral TKAs) with 16 GMK Sphere implants, at a mean age of 66 years (53 to 76) with a mean BMI of 30 kg/m. 2. (20 to 35). The motions of all 16 knees were observed using pulsed fluoroscopy during a number of weight-bearing and non-weight-bearing static and dynamic activities. Results. During maximally flexed kneeling and lunging activities, the mean tibial internal rotation was 8° (standard deviation (. sd. ) 6). At a mean 112° flexion (. sd. 16) during lunging, the medial and lateral condyles were a mean of 2 mm (. sd. 3) and 8 mm (. sd. 4) posterior to a transverse line passing through the centre of the medial tibial concavity. With a mean flexion of 117° (. sd. 14) during kneeling, the medial and lateral condyles were a mean of 1 mm (. sd. 4) anterior and 6 mm (. sd. 4) posterior to the same line. During dynamic stair and pivoting activities, there was a mean anteroposterior translation of 0 mm to 2 mm of the medial femoral condyle. Backward lateral condylar translation occurred and was linearly related to tibial rotation. Conclusion. The GMK Sphere TKA in our study group shows movements similar in pattern, although reduced in magnitude, to those in recent reports relating to normal knees during several activities. Specifically, little or no translation of the medial femoral condyle was observed during flexion, but there was posterior roll-back of the lateral femoral condyle, equating to tibiofemoral rotation. We conclude that the GMK Sphere is anteroposteriorly stable medially and permits rotation about the medial compartment. Cite this article: Professor G. Scott. Can a total knee arthroplasty be both rotationally unconstrained and anteroposteriorly stabilised?: A pulsed fluoroscopic investigation. Bone Joint Res 2016;5:80–86. DOI: 10.1302/2046-3758.53.2000621

Aims. The morphometry of the distal femur was largely studied to improve bone-implant fit in total knee arthroplasty (TKA), but little is known about the asymmetry of the posterior condyles. This study aimed to investigate the dimensions of the posterior condyles and the influence of externally rotating the femoral component on potential prosthetic overhang or under-coverage. Patients and Methods. We analysed the shape of 110 arthritic knees at the time of primary TKA using pre-operative CT scans. The height and width of each condyle were measured at the posterior femoral cut in neutral position, and in 3º and 5º of external rotation, using both central and medial referencing systems. We compared the morphological characteristics with those of 14 TKA models. Results. In the neutral position, the dimensions of the condyles were nearly equal. Externally rotating the femoral cut by 3º and 5º with ‘central referencing’ induced width asymmetry >  3 mm in 23 (21%) and 33 (30%) knees respectively, while with ‘medial referencing’ it induced width asymmetry > 3 mm in 43 (39%) and 75 (68%) knees respectively. The asymmetries induced by rotations were not associated with gender, aetiology or varus-valgus alignment. Conclusion. External rotation may amplify the asymmetry between the medial and lateral condyles, and exacerbate prosthetic overhang, particularly in the superolateral zone. ‘Central referencing’ guides result in less potential prosthetic overhang than ‘medial referencing’ guides. Cite this article: Bone Joint J 2017;99-B:894–903

Ensuring correct rotation of the femoral component is a challenging aspect of patellofemoral replacement surgery. Rotation equal to the epicondylar axis or marginally more external rotation is acceptable. Internal rotation is associated with poor outcomes. This paper comprises two studies evaluating the use of the medial malleolus as a landmark to guide rotation. We used 100 lower-leg anteroposterior radiographs to evaluate the reliability of the medial malleolus as a landmark. Assessment was made of the angle between the tibial shaft and a line from the intramedullary rod entry site to the medial malleolus. The femoral cut was made in ten cadaver knees using the inferior tip of the medial malleolus as a landmark for rotation. Rotation of the cut relative to the anatomical epicondylar axis was assessed using CT. The study of radiographs found the position of the medial malleolus relative to the tibial axis is consistent. Using the inferior tip of the medial malleolus in the cadaver study produced a mean external rotation of 1.6° (0.1° to 3.7°) from the anatomical epicondylar axis. Using the inferior tip of the medial malleolus to guide the femoral cutting jig avoids internal rotation and introduces an acceptable amount of external rotation of the femoral component

We undertook a prospective study in 51 male patients aged between 17 and 27 years to ascertain whether immobilisation after primary traumatic anterior dislocation of the shoulder in external rotation was more effective than immobilisation in internal rotation in preventing recurrent dislocation in a physically active population. Of the 51 patients, 24 were randomised to be treated by a traditional brace in internal rotation and 27 were immobilised in external rotation of 15° to 20°. After immobilisation, the patients undertook a standard regime of physiotherapy and were then assessed clinically for evidence of instability. When reviewed at a mean of 33.4 months (24 to 48) ten from the external rotation group (37%) and ten from the internal rotation group (41.7%) had sustained a futher dislocation. There was no statistically significant difference (p = 0.74) between the groups. Our findings show that external rotation bracing may not be as effective as previously reported in preventing recurrent anterior dislocation of the shoulder

We present the long-term results of open surgery for internal shoulder rotational deformity in brachial plexus birth palsy (BPBP). From 1997 to 2005, 207 patients (107 females, 100 males, mean age 6.2 (0.6 to 34)) were operated on with subscapularis elongation and/or latissimus dorsi to infraspinatus transfer. Incongruent shoulder joints were relocated. The early results of these patients has been reported previously. We analysed 118 (64 females, 54 males, mean age 15.1 (7.6 to 34)) of the original patient cohort at a mean of 10.4 years (7.0 to 15.1) post-operatively. A third of patients with relocated joints had undergone secondary internal rotational osteotomy of the humerus. A mixed effects models approach was used to evaluate the effects of surgery on shoulder rotation, abduction, and the Mallet score. Independent factors were time (pre-and post-surgery), gender, age, joint category (congruent, relocated, relocated plus osteotomy) and whether or not a transfer had been performed. Data from a previously published short-term evaluation were reworked in order to obtain pre-operative values. The mean improvement in external rotation from pre-surgery to the long-term follow-up was 66.5° (95% confidence interval (CI) 61.5 to 71.6). The internal rotation had decreased by a mean of 22.6° (95% CI -18.7 to -26.5). The mean improvement in the three-grade aggregate Mallet score was 3.1 (95% CI 2.7 to 3.4), from 8.7 (95% CI 8.4 to 9.0) to 11.8 (11.5 to 12.1). Our results show that open subscapularis elongation achieves good long-term results for patients with BPBP and an internal rotation contracture, providing lasting joint congruency and resolution of the trumpet sign, but with a moderate mean loss of internal rotation. Cite this article: Bone Joint J 2014;96-B:1411–18

Objectives. Fractures of the proximal femur are a common clinical problem, and a number of orthopaedic devices are available for the treatment of such fractures. The objective of this study was to assess the rotational stability, a common failure predictor, of three different rotational control design philosophies: a screw, a helical blade and a deployable crucifix. Methods. Devices were compared in terms of the mechanical work (W) required to rotate the implant by 6° in a bone substitute material. The substitute material used was Sawbones polyurethane foam of three different densities (0.08 g/cm. 3. , 0.16 g/cm. 3. and 0.24 g/cm. 3. ). Each torsion test comprised a steady ramp of 1°/minute up to an angular displacement of 10°. Results. The deployable crucifix design (X-Bolt), was more torsionally stable, compared to both the dynamic hip screw (DHS, p = 0.008) and helical blade (DHS Blade, p= 0.008) designs in bone substitute material representative of osteoporotic bone (0.16 g/cm. 3. polyurethane foam). In 0.08 g/cm. 3. density substrate, the crucifix design (X-Bolt) had a higher resistance to torsion than the screw (DHS, p = 0.008). There were no significant differences (p = 0.101) between the implants in 0.24 g/cm. 3. density bone substitute. Conclusions. Our findings indicate that the clinical standard proximal fracture fixator design, the screw (DHS), was the least effective at resisting torsional load, and a novel crucifix design (X-Bolt), was the most effective design in resisting torsional load in bone substitute material with density representative of osteoporotic bone. At other densities the torsional stability was also higher for the X-Bolt, although not consistently significant by statistical analysis. Cite this article: J. D. Gosiewski, T. P. Holsgrove, H. S. Gill. The efficacy of rotational control designs in promoting torsional stability of hip fracture fixation. Bone Joint Res 2017;6:270–276. DOI: 10.1302/2046-3758.65.BJR-2017-0287.R1

We describe the survivorship of the Medial Rotation total knee replacement (TKR) at ten years in 228 cemented primary replacements implanted between October 1994 and October 2006, with their clinical and radiological outcome. This implant has a highly congruent medial compartment, with the femoral component represented by a portion of a sphere which articulates with a matched concave surface on the medial side of the tibial insert. There were 78 men (17 bilateral TKRs) and 111 women (22 bilateral TKRs) with a mean age of 67.9 years (28 to 90). All the patients were assessed clinically and radiologically using the American Knee Society scoring systems. The mean follow-up was for six years (1 to 13) with only two patients lost to follow-up and 34 dying during the period of study, one of whom had required revision for infection. There were 11 revisions performed in total, three for aseptic loosening, six for infection, one for a periprosthetic fracture and one for a painful but well-fixed replacement performed at another centre. With revision for any cause as the endpoint, the survival at ten years was 94.5% (95% CI 85.1 to 100), and with aseptic loosening as the endpoint 98.4% (95% CI 93 to 100). The mean American Knee Society score improved from 47.6 (0 to 88) to 72.2 (26 to 100) and for function from 45.1 (0 to 100) to 93.1 (45 to 100). Radiological review failed to detect migration in any of the surviving knees. The clinical and radiological results of the Medial Rotation TKR are satisfactory at ten years. The increased congruence of the medial compartment has not led to an increased rate of loosening and continued use can be supported

In this in vitro study of the hip joint we examined which soft tissues act as primary and secondary passive rotational restraints when the hip joint is functionally loaded. A total of nine cadaveric left hips were mounted in a testing rig that allowed the application of forces, torques and rotations in all six degrees of freedom. The hip was rotated throughout a complete range of movement (ROM) and the contributions of the iliofemoral (medial and lateral arms), pubofemoral and ischiofemoral ligaments and the ligamentum teres to rotational restraint was determined by resecting a ligament and measuring the reduced torque required to achieve the same angular position as before resection. The contribution from the acetabular labrum was also measured. Each of the capsular ligaments acted as the primary hip rotation restraint somewhere within the complete ROM, and the ligamentum teres acted as a secondary restraint in high flexion, adduction and external rotation. The iliofemoral lateral arm and the ischiofemoral ligaments were primary restraints in two-thirds of the positions tested. Appreciation of the importance of these structures in preventing excessive hip rotation and subsequent impingement/instability may be relevant for surgeons undertaking both hip joint preserving surgery and hip arthroplasty. Cite this article: Bone Joint J 2015; 97-B:484–91

Our aim in this retrospective study of 52 children with spastic hemiplegia was to determine the factors which affected the amount of residual pelvic rotation after single-event multilevel surgery. The patients were divided into two groups, those who had undergone femoral derotation osteotomy and those who had not. Pelvic rotation improved significantly after surgery in the femoral osteotomy group (p < 0.001) but not in the non-femoral osteotomy group. Multiple regressions identified the following three independent variables, which significantly affected residual pelvic rotation: the performance of femoral derotation osteotomy (p = 0.049), the pre-operative pelvic rotation (p = 0.003) and the post-operative internal rotation of the hip (p = 0.001). We concluded that there is a decrease in the amount of pelvic rotation after single-event multilevel surgery with femoral derotation osteotomy. However, some residual rotation may persist when patients have severe rotation before surgery

At least four ways have been described to determine femoral component rotation, and three ways to determine tibial component rotation in total knee replacement (TKR). Each method has its advocates and each has an influence on knee kinematics and the ultimate short and long term success of TKR. Of the four femoral component methods, the author prefers rotating the femoral component in flexion to that amount that establishes a stable symmetrical flexion gap. This judgement is made after the soft tissues of the knee have been balanced in extension. Of the three tibial component methods, the author prefers rotating the tibial component into congruency with the established femoral component rotation with the knee is in extension. This yields a rotationally congruent articulation during weight-bearing and should minimise the torsional forces being transferred through a conforming tibial insert, which could lead to wear to the underside of the tibial polyethylene. Rotating platform components will compensate for any mal-rotation, but can still lead to pain if excessive tibial insert rotation causes soft-tissue impingement. Cite this article: Bone Joint J 2013;95-B, Supple A:140–3