The piriformis muscle is an important landmark in the surgical anatomy of the hip, particularly the posterior approach for total hip replacement (THR). Standard orthopaedic teaching dictates that the tendon must be cut in to allow adequate access to the superior part of the acetabulum and the femoral medullary canal. However, in our experience a routine THR can be performed through a posterior approach without sacrificing this tendon. We dissected the proximal femora of 15 cadavers in order to clarify the morphological anatomy of the piriformis tendon. We confirmed that the tendon attaches on the crest of the greater trochanter, in a position superior to the trochanteric fossa, away from the entry point for broaching the intramedullary canal during THR. The tendon attachment site encompassed the summit and medial aspect of the greater trochanter as well as a variable attachment to the fibrous capsule of the hip joint. In addition we dissected seven cadavers resecting all posterior attachments except the piriformis muscle and tendon in order to study their relations to the hip joint, as the joint was flexed. At flexion of 90° the piriformis muscle lay directly posterior to the hip joint. The piriform fossa is a term used by orthopaedic surgeons to refer the trochanteric fossa and normally has no relation to the attachment site of the piriformis tendon. In hip flexion the piriformis lies directly behind the hip joint and might reasonably be considered to contribute to the stability of the joint. We conclude that the anatomy of the piriformis muscle is often inaccurately described in the current surgical literature and terms are used and interchanged inappropriately. Cite this article: Bone Joint J 2013;95-B:764–9

The inferior gluteal artery is described in standard anatomy textbooks as contributing to the blood supply of the hip through an anastomosis with the medial femoral circumflex artery. The site(s) of the anastomosis has not been described previously. We undertook an injection study to define the anastomotic connections between these two arteries and to determine whether the inferior gluteal artery could supply the lateral epiphyseal arteries alone. From eight fresh-frozen cadaver pelvic specimens we were able to inject the vessels in 14 hips with latex moulding compound through either the medial femoral circumflex artery or the inferior gluteal artery. Injected vessels around the hip were then carefully exposed and documented photographically. In seven of the eight specimens a clear anastomosis was shown between the two arteries adjacent to the tendon of obturator externus. The terminal vessel arising from this anastomosis was noted to pass directly beneath the posterior capsule of the hip before ascending the superior aspect of the femoral neck and terminating in the lateral epiphyseal vessels. At no point was the terminal vessel found between the capsule and the conjoined tendon. The medial femoral circumflex artery receives a direct supply from the inferior gluteal artery immediately before passing beneath the capsule of the hip. Detailed knowledge of this anatomy may help to explain the development of avascular necrosis after hip trauma, as well as to allow additional safe surgical exposure of the femoral neck and head

The primary source for the blood supply of the head of the femur is the deep branch of the medial femoral circumflex artery (MFCA). In posterior approaches to the hip and pelvis the short external rotators are often divided. This can damage the deep branch and interfere with perfusion of the head. We describe the anatomy of the MFCA and its branches based on dissections of 24 cadaver hips after injection of neoprene-latex into the femoral or internal iliac arteries. The course of the deep branch of the MFCA was constant in its extracapsular segment. In all cases there was a trochanteric branch at the proximal border of quadratus femoris spreading on to the lateral aspect of the greater trochanter. This branch marks the level of the tendon of obturator externus, which is crossed posteriorly by the deep branch of the MFCA. As the deep branch travels superiorly, it crosses anterior to the conjoint tendon of gemellus inferior, obturator internus and gemellus superior. It then perforates the joint capsule at the level of gemellus superior. In its intracapsular segment it runs along the posterosuperior aspect of the neck of the femur dividing into two to four subsynovial retinacular vessels. We demonstrated that obturator externus protected the deep branch of the MFCA from being disrupted or stretched during dislocation of the hip in any direction after serial release of all other soft-tissue attachments of the proximal femur, including a complete circumferential capsulotomy. Precise knowledge of the extracapsular anatomy of the MFCA and its surrounding structures will help to avoid iatrogenic avascular necrosis of the head of the femur in reconstructive surgery of the hip and fixation of acetabular fractures through the posterior approach

In order to investigate the functional anatomy of gluteus minimus we dissected 16 hips in fresh cadavers. The muscle originates from the external aspect of the ilium, between the anterior and inferior gluteal lines, and also at the sciatic notch from the inside of the pelvis where it protects the superior gluteal nerve and artery. It inserts anterosuperiorly into the capsule of the hip and continues to its main insertion on the greater trochanter. Based on these anatomical findings, a model was developed using plastic bones. A study of its mechanics showed that gluteus minimus acts as a flexor, an abductor and an internal or external rotator, depending on the position of the femur and which part of the muscle is active. It follows that one of its functions is to stabilise the head of the femur in the acetabulum by tightening the capsule and applying pressure on the head. Careful preservation or reattachment of the tendon of gluteus minimus during surgery on the hip is strongly recommended

Three-dimensional surface models of the normal hemipelvis derived from volumetric CT data on 42 patients were used to determine the radius, depth and orientation of the native acetabulum. A sphere fitted to the lunate surface and a plane matched to the acetabular rim were used to calculate the radius, depth and anatomical orientation of the acetabulum. For the 22 females the mean acetabular abduction, anteversion, radius and normalised depth were 57.1° (50.7° to 66.8°), 24.1° (14.0° to 33.3°), 25 mm (21.7 to 30.3) and 0.79 mm (0.56 to 1.04), respectively. The same parameters for the 20 males were 55.5° (47.7° to 65.9°), 19.3° (8.5° to 32.3°), 26.7 mm (24.5 to 28.7) and 0.85 mm (0.65 to 0.99), respectively.

The orientation of the native acetabulum did not match the safe zone for acetabular component placement described by Lewinnek. During total hip replacement surgeons should be aware that the average abduction angle of the native acetabulum exceeds that of the safe zone angle. If the concept of the safe zone angle is followed, abduction of the acetabular component should be less than the abduction of the native acetabulum by approximately 10°.

Using radiography and computer tomography (CT) we studied the morphology of 83 hips in 69 Caucasian adults with osteoarthritis secondary to developmental dysplasia of the hip (DDH). A previously published series of 310 hips with primary osteoarthritis was used as a control group. According to the Crowe classification, 33 of the dysplastic hips were graded as class I, 27 as class II and 23 as class III or class IV.

The intramedullary femoral canal had reduced mediolateral and anteroposterior dimensions in all groups compared with the control group. Only in Crowe class II hips was the femoral neck-shaft angle increased. The proximal femur had more anteversion in all the developmental dysplasia of the hip groups, ranging from 2° to 80°. Templated measurement of acetabular dimensions for plain radiography closely matched measurements taken by CT.

The results of our study confirm the observations previously confined to the Japanese population.

Aims. The Exeter V40 femoral stem is the most implanted stem in the National Joint Registry (NJR) for primary total hip arthroplasty (THA). In 2004, the 44/00/125 stem was released for use in ‘cement-in-cement’ revision cases. It has, however, been used ‘off-label’ as a primary stem when patient anatomy requires a smaller stem with a 44 mm offset. We aimed to investigate survival of this implant in comparison to others in the range when used in primary THAs recorded in the NJR. Methods. We analyzed 328,737 primary THAs using the Exeter V40 stem, comprising 34.3% of the 958,869 from the start of the NJR to December 2018. Our exposure was the stem, and the outcome was all-cause construct revision. We stratified analyses into four groups: constructs using the 44/00/125 stem, those using the 44/0/150 stem, those including a 35.5/125 stem, and constructs using any other Exeter V40 stem. Results. In all 328,737 THAs using an Exeter V40 stem, the revision estimate was 2.8% (95% confidence interval (CI) 2.7 to 2.8). The 44/00/125 stem was implanted in 2,158 primary THAs, and the ten-year revision estimate was 4.9% (95% CI 3.6 to 6.8). Controlling for age, sex, year of operation, indication, and American Society of Anesthesiologists grade demonstrated an increased overall hazard of revision for constructs using the 44/00/125 stem compared to constructs using other Exeter V40 femoral stems (hazard ratio 1.8 (95% CI 1.4 to 2.3)). Conclusion. Although the revision estimate is within the National Institute for Health and Care Excellence ten-year benchmark, survivorship of constructs using the 44/00/125 stem appears to be lower than the rest of the range. Adjusted analyses will not take into account ‘confounding by indication’, e.g. patients with complex anatomy who may have a higher risk of revision. Surgeons and patients should be reassured but be aware of the observed increased revision estimate, and only use this stem when other implants are not suitable. Cite this article: Bone Joint J 2023;105-B(5):504–510

Aims. Developmental dysplasia of the hip (DDH) describes a pathological relationship between the femoral head and acetabulum. Periacetabular osteotomy (PAO) may be used to treat this condition. The aim of this study was to evaluate the results of PAO in adolescents and adults with persistent DDH. Methods. Patients were divided into four groups: A, adolescents who had not undergone surgery for DDH in childhood (25 hips); B, adolescents who had undergone surgery for DDH in childhood (20 hips); C, adults with DDH who had not undergone previous surgery (80 hips); and D, a control group of patients with healthy hips (70 hips). The radiological evaluation of digital anteroposterior views of hips included the Wiberg angle (centre-edge angle (CEA)), femoral head cover (FHC), medialization, distalization, and the ilioischial angle. Clinical assessment involved the Harris Hip Score (HHS) and gluteal muscle performance assessment. Results. Significant improvements in radiological parameters were achieved in all measurements in all groups (p < 0.05). The greatest improvement was in CEA (mean of 19° (17.2° to 22.3°) in Group B), medialization (mean of 3 mm (0.9 to 5.2) in Group C), distalization (mean of 6 mm (3.5 to 8.2) in Group B), FHC (mean of 17% (12.7% to 21.2%) in Group B), and ilioischial angle (mean of 5° (2.3° to 8.1°) in Group B). There were significant improvements in the mean HHS and gluteal muscle performance scores postoperatively in all three groups. Conclusion. The greatest correction of radiological parameters and clinical outcomes was found in patients who had undergone hip surgery in childhood. Although the surgical treatment of DDH in childhood makes subsequent hip surgery more difficult due to scarring, adhesions, and altered anatomy, it requires less correction of the deformity and has a beneficial effect on the outcome of PAO in adolescence and early adulthood. Cite this article: Bone Joint J 2022;104-B(7):775–780

Aims. Despite advances in the treatment of paediatric hip disease, adolescent and young adult patients can develop early onset end-stage osteoarthritis. The aims of this study were to address the indications and medium-term outcomes for total hip arthroplasty (THA) with ceramic bearings for teenage patients. Methods. Surgery was performed by a single surgeon working in the paediatric orthopaedic unit of a tertiary referral hospital. Databases were interrogated from 2003 to 2017 for all teenage patients undergoing THA with a minimum 2.3 year follow-up. Data capture included patient demographics, the underlying hip pathology, number of previous surgeries, and THA prostheses used. Institutional ethical approval was granted to contact patients for prospective clinical outcomes and obtain up-to-date radiographs. In total, 60 primary hips were implanted in 51 patients (35 female, 16 male) with nine bilateral cases. The mean age was 16.7 years (12 to 19) and mean follow-up was 9.3 years (2.3 to 16.8). Results. The most common indication for teenage hip arthroplasty was avascular necrosis secondary to slipped upper femoral epiphysis (31%; n = 16). Overall, 64% of patients (n = 33) had undergone multiple previous operations. The survival at follow-up was 97%; two patients required revision for aseptic loosening (one femoral stem, one acetabular component). Both patients had fused hips noted at the time of arthroplasty. A further two patients had radiolucent lines but were asymptomatic. At latest follow-up the mean Oxford Hip Score was 44 (31 to 48) and a Visual Analogue Scale measurement of 1.5, indicating satisfactory function. Conclusion. Operating on this cohort can be complicated by multiple previous surgeries and distorted anatomy, which in some cases require custom-made prostheses. We have demonstrated a good outcome with low revision rate in this complex group of patients. Cite this article: Bone Joint J 2020;102-B(11):1491–1496

Aims. Modular or custom-made femoral components have been preferred for total hip arthroplasty (THA) in patients with a history of Perthes’ disease because of the distortion in the anatomy of the proximal femur. However, it has not been established whether a monobloc cementless stem will fit the distorted proximal femur or whether the results of the procedure are satisfactory in this group of patients. Patients and Methods. We reviewed 68 consecutive patients who had undergone THA for childhood Perthes’ disease between June 2003 and December 2008. There were 35 men and 33 women with a mean age of 48 years (16 to 73) at the time of index arthroplasty. Their mean body mass index was 24.4 (18.3 to 32.9). Of the 68 hips, 32 were classified as Stulberg class III and 36 as class IV. The mean pre-operative shortening of the affected leg was 17.2 mm (5 to 34). The minimum follow-up was five years (mean 8.5 years; 5.2 to 10). Results. An intra-operative calcar fracture occurred in eight hips (11.8%) and was successfully treated by cerclage wiring. The mean stem version was 14.6° (-2.3 to 30; standard deviation (. sd. ) 7.3). The mean acetabular component abduction was 40.2° (23.7 to 56.0; . sd. 6.5) and the mean anteversion 28.3° (6.4 to 43.0; . sd. 7.6), respectively. The mean follow-up was 8.5 years (5.2 to 10). No dislocations occurred and no hips were revised during the course of the study. At final follow-up, the mean Harris Hip Score was 91 points (59 to 100) and the mean University of California, Los Angeles activity score was 3.2 (2 to 8). Conclusion. Monobloc cementless stems reliably restore the anatomy in Perthes’ disease at THA without the need for custom-made or modular implants. Cite this article: Bone Joint J 2017;99-B:440–444

The acetabular labrum is a soft-tissue structure which lines the acetabular rim of the hip joint. Its role in hip joint biomechanics and joint health has been of particular interest over the past decade. In normal hip joint biomechanics, the labrum is crucial in retaining a layer of pressurised intra-articular fluid for joint lubrication and load support/distribution. Its seal around the femoral head is further regarded as a contributing to hip stability through its suction effect. The labrum itself is also important in increasing contact area thereby reducing contact stress. Given the labrum’s role in normal hip joint biomechanics, surgical techniques for managing labral damage are continuously evolving as our understanding of its anatomy and function continue to progress. The current paper aims to review the anatomy and biomechanical function of the labrum and how they are affected by differing surgical techniques. Take home message: The acetabular labrum plays a critical role in hip function and maintaining and restoring its function during surgical intervention remain an essential goal. Cite this article: Bone Joint J 2016;98-B:730–5

The accurate reconstruction of hip anatomy and biomechanics is thought to be important in achieveing good clinical outcomes following total hip arthroplasty (THA). To this end some newer hip designs have introduced further modularity into the design of the femoral component such that neck­shaft angle and anteversion, which can be adjusted intra-operatively. The clinical effect of this increased modularity is unknown. We have investigated the changes in these anatomical parameters following conventional THA with a prosthesis of predetermined neck–shaft angle and assessed the effect of changes in the hip anatomy on clinical outcomes. . In total, 44 patients (mean age 65.3 years (standard deviation (. sd. ) 7); 17 male/27 female; mean body mass index 26.9 (kg/m²) (. sd. 3.1)) underwent a pre- and post-operative three-dimensional CT scanning of the hip. The pre- and post-operative neck–shaft angle, offset, hip centre of rotation, femoral anteversion, and stem alignment were measured. Additionally, a functional assessment and pain score were evaluated before surgery and at one year post-operatively and related to the post-operative anatomical changes. The mean pre-operative neck–shaft angle was significantly increased by 2.8° from 128° (. sd.  6.2; 119° to 147°) to 131° (. sd. 2.1; 127° to 136°) (p = 0.009). The mean pre-operative anteversion was 24.9° (. sd. 8; 7.9 to 39.1) and reduced to 7.4° (. sd. 7.3; -11.6° to 25.9°) post-operatively (p < 0.001). The post-operative changes had no influence on function and pain. Using a standard uncemented femoral component, high pre- and post-operative variability of femoral anteversion and neck–shaft angles was found with a significant decrease of the post-operative anteversion and slight increase of the neck–shaft angles, but without any impact on clinical outcome. Cite this article: Bone Joint J 2015;97-B:1615–22

Aims. The modified Dunn procedure has the potential to restore the anatomy in hips with severe slipped capital femoral epiphyses (SCFE). However, there is a risk of developing avascular necrosis of the femoral head (AVN). In this paper, we report on clinical outcome, radiological outcome, AVN rate and complications, and the cumulative survivorship at long-term follow-up in patients undergoing the modified Dunn procedure for severe SCFE. Patients and Methods. We performed a retrospective analysis involving 46 hips in 46 patients treated with a modified Dunn procedure for severe SCFE (slip angle > 60°) between 1999 and 2016. At nine-year-follow-up, 40 hips were available for clinical and radiological examination. Mean preoperative age was 13 years, and 14 hips (30%) presented with unstable slips. Mean preoperative slip angle was 64°. Kaplan–Meier survivorship was calculated. Results. At the latest follow-up, the mean Merle d’Aubigné and Postel score was 17 points (14 to 18), mean modified Harris Hip Score was 94 points (66 to 100), and mean Hip Disability and Osteoarthritis Outcome Score was 91 points (67 to 100). Postoperative slip angle was 7° (1° to 16°). One hip (2%) had progression of osteoarthritis (OA). Two hips (5%) developed AVN of the femoral head and required further surgery. Three other hips (7%) underwent implant revision due to screw breakage or change of wires. Cumulative survivorship was 86% at ten-year follow-up. Conclusion. The modified Dunn procedure for severe SCFE resulted in a low rate of AVN, low risk of progression to OA, and high functional scores at long-term follow-up. The slip deformities were mainly corrected but secondary impingement deformities can develop in some hips and may require further surgical treatment. Cite this article: Bone Joint J 2019;101-B:403–414

Aims. Morphological abnormalities are present in patients with developmental dysplasia of the hip (DDH). We studied and compared the pelvic anatomy and morphology between the affected hemipelvis with the unaffected side in patients with unilateral Crowe type IV DDH using 3D imaging and analysis. Methods. A total of 20 patients with unilateral Crowe-IV DDH were included in the study. The contralateral side was considered normal in all patients. A coordinate system based on the sacral base (SB) in a reconstructed pelvic model was established. The pelvic orientations (tilt, rotation, and obliquity) of the affected side were assessed by establishing a virtual anterior pelvic plane (APP). The bilateral coordinates of the anterior superior iliac spine (ASIS) and the centres of hip rotation were established, and parameters concerning size and volume were compared for both sides of the pelvis. Results. The ASIS on the dislocated side was located inferiorly and anteriorly compared to the healthy side (coordinates on the y-axis and z-axis; p = 0.001; p = 0.031). The centre of hip rotation on the dislocated side was located inferiorly and medially compared to the healthy side (coordinates on the x-axis and the y-axis; p < 0.001; p = 0.003). The affected hemipelvis tilted anteriorly in the sagittal plane (mean 8.05° (SD 3.57°)), anteriorly rotated in the transverse plane (mean 3.31° (SD 1.41°)), and tilted obliquely and caudally in the coronal plane (mean 2.04° (SD 0.81°)) relative to the healthy hemipelvis. The affected hemipelvis was significantly smaller in the length, width, height, and volume than the healthy counterpart. (p = 0.014; p = 0.009; p = 0.035; p = 0.002). Conclusion. Asymmetric abnormalities were identified on the affected hemipelvis in patients with the unilateral Crowe-IV DDH using 3D imaging techniques. Improved understanding of the morphological changes may influence the positioning of the acetabular component at THA. Acetabular component malpositioning errors caused by anterior tilt of the affected hemi pelvis and the abnormal position of the affected side centre of rotation should be considered by orthopaedic surgeons when undertaking THA in patients with Crowe-IV DDH. Cite this article: Bone Joint J 2020;102-B(10):1311–1318

Aims

Lateral femoral cutaneous nerve (LFCN) injury is a potential complication after the direct anterior approach for total hip arthroplasty (DAA-THA). The aim of this study was to determine how the location of the fasciotomy in DAA-THA affects LFCN injury.

Aims

Spinopelvic pathology increases the risk for instability following total hip arthroplasty (THA), yet few studies have evaluated how pathology varies with age or sex. The aims of this study were: 1) to report differences in spinopelvic parameters with advancing age and between the sexes; and 2) to determine variation in the prevalence of THA instability risk factors with advancing age.

In this paper we propose a new classification of neurogenic peri-articular heterotopic ossification (HO) of the hip based on three-dimensional (3D) CT, with the aim of improving pre-operative planning for its excision. . A total of 55 patients (73 hips) with clinically significant HO after either traumatic brain or spinal cord injury were assessed by 3D-CT scanning, and the results compared with the intra-operative findings. At operation, the gross pathological anatomy of the HO as identified by 3D-CT imaging was confirmed as affecting the peri-articular hip muscles to a greater or lesser extent. We identified seven patterns of involvement: four basic (anterior, medial, posterior and lateral) and three mixed (anteromedial, posterolateral and circumferential). Excellent intra- and inter-observer agreement, with kappa values > 0.8, confirmed the reproducibility of the classification system. We describe the different surgical approaches used to excise the HO which were guided by the 3D-CT findings. Resection was always successful. . 3D-CT imaging, complemented in some cases by angiography, allows the surgeon to define the 3D anatomy of the HO accurately and to plan its surgical excision with precision. Cite this article: Bone Joint J 2015; 97-B:899–904

Aims

There has been limited literature regarding outcomes of acetabular rim syndrome (ARS) with persistent acetabular os in the setting of acetabular dysplasia. The purpose of this study was to characterize a cohort of adolescent and young adult patients with ARS with persistent os and compare their radiological and clinical outcomes to patients with acetabular dysplasia without an os.

Aims

The Birmingham Hip Resurfacing (BHR) arthroplasty has been used as a surgical treatment of coxarthrosis since 1997. We present 20-year results of 234 consecutive BHRs performed in our unit.

Aims

The risk of mechanical failure of modular revision hip stems is frequently mentioned in the literature, but little is currently known about the actual clinical failure rates of this type of prosthesis. The current retrospective long-term analysis examines the distal and modular failure patterns of the Prevision hip stem from 18 years of clinical use. A design improvement of the modular taper was introduced in 2008, and the data could also be used to compare the original and the current design of the modular connection.