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

Introduction. The debate regarding the importance of preserving the blood supply to the femoral head (FH) and neck during hip resurfacing arthroplasty (HRA) is ongoing. Several surgeons continue to advocate for the preservation of the blood supply to the resurfaced heads for both the current HRA techniques and more biologic approaches for FH resurfacing. Despite alternative blood-preserving approaches for HRA, many surgeons continue to use the posterior approach (PA) due to personal preference and comfort. It is commonly accepted that the PA inevitably damages the deep branch of the medial femoral circumflex artery (MFCA). This study seeks to evaluate and measure the anatomical course of the ascending and deep branch of the MFCA to better describe the area in danger during the posterior approach. Methods. In 20 fresh-frozen cadaveric hips, we cannulated the MFCA and injected a urethane compound. The Kocher-Langenbeck approach was used in all specimens. The deep branch of the MFCA was identified at the proximal border of the QF and measurements were taken. The QF was incised medially and elevated laterally, maintaining the relationship of the ascending branch and QF, and distances from the lesser trochanter were measured. The deep branch was dissected and followed to its capsular insertion to assess the course and relation to the obturatur externus (OE) tendon and the conjoint tendon (CT) of the short external rotators. Results. Gross dissection revealed that the transition point from transverse to ascending branch of the MFCA at the anterior surface of the QF was at an average distance of 2.2 cm (range 2–2.3 cm) proximal and 1.2 cm (range 0.5–1.9 cm) medial to the lesser trochanter. The ascending branch runs caudally within fat tissue that divides the QF and OE at an average distance of 1.5 cm (range 0.7–2.3 cm) from the QF greater trochanter insertion. At the superior border of the QF, the MFCA continues as the deep branch posterior to the OE tendon at an average distance of 1.3 cm (range 0.6–1.9 cm) from the OE femoral insertion. The deep branch was noted to enter the capsule at an average distance of 0.3 cm (range 0–0.5 cm) from the distal border of the CT and 1.2 cm (range 0.6–1.9 cm) from the CT femoral insertion. Discussion and Conclusion. The ascending branch of the MFCA runs in the anterior surface of the QF at a distance of 1.5 cm from the femoral insertion. When the QF myotomy is performed, commonly 0.5–0.8 cm from the insertion to the femur, the vessel get disrupted or stays medial to the myotomy and can stretch/disrupt when the femur is dislocated and translated anteriorly. Tenotomies of the OE and CT should stay at least 1.5 cm from the femoral insertion to preserve the deep branch of the MFCA. This study provides unreported topographic anatomy of the ascending and deep branch of the MFCA, which can help develop an improved blood-preserving posterior approach for HRA

Introduction. Precise knowledge of the Femoral Head (FH) arterial supply is critical to avoid FH avascular necrosis following open and arthroscopic intra-capsular surgical procedures about the hip. The Medial Femoral Circumflex Artery (MFCA) provides the primary FH vascular contribution. Distribution of vascular foramina at the Femoral Head-Neck Junction (FHNJ) has been reported previously using an imaginary clock face. However, no quantitative information exists on the precise Capsular Insertion (CI) and intra-capsular course of the MFCA Terminal Branches (TBs) supplying the FH. This study seeks to determine the precise anatomic location of the MFCA's TBs supplying the FH, in order to help avoid iatrogenic vascular damage during surgical intervention. Methods. In 14 fresh-frozen cadaveric hips (9 left and 5 right), we cannulated the MFCA and injected a polyurethane compound. Using a posterior approach, careful dissection of the MFCA allowed us to identify and document the extra- and intra-capsular course of the TBs penetrating the FHNJ and supplying the FH. An H-type capsulotomy provided joint access while preserving the intracapsular Retinaculum of Weitbrecht (RW), followed by circumferential capsulotomy at the acetabular margin exposing the FH. The dome of the FH was osteotomized 5 mm proximal to the Articular Border (AB) providing a flat surface for our 360° scale. Right-side equivalents were used for data processing. Results. Gross dissection revealed a constant single branch arising from the transverse MFCA penetrating the capsule at the level of the anterior-inferior neck at 177° (range 167–187°), then courses within the medial RW obliquely (elevated from the neck) to the posterior-inferior FHNJ (Figure 1). This vessel was found to have an average of 5 TBs (range 3–9) penetrating the inferior FHNJ 4 mm (range 1–7 mm) from the AB at 204° (range 145–244°; 14% . 10. /. 69. anterior; 86% . 59. /. 69. posterior). In 79% (. 11. /. 14. ) of specimens, an average of 1.5 branches (range 1–3) arising from the ascending MFCA entered the Femoral Capsular Attachment (FCA) at 244° (range 216–269°), running subsynovial through the neck, and terminating in 2 TBs (range 1–3) penetrating the inferior-posterior FHNJ 5 mm (range 3–9) from the AB at 254° (range 207–281°). The deep branch of the MFCA penetrated the FCA at 327° (range 310–335°) providing an average of 6 TBs (range 4–9) running subsynovial and within the lateral RW, finally penetrating the superior FHNJ 6 mm (range 4–9) from the AB at 339° (range 286–25°; 20%. 15/74. anterior; 80%. 59/74. posterior). Discussion and Conclusion. This study demonstrates that TBs of the MFCA penetrate the joint through the mid-substance of the capsule (from the transverse MFCA) or the FCA (from the ascending or deep MFCA). Once intra-capsular, these vessels course subsynovial or within the RW and terminate at the posterior FHNJ superiorly (from the deep MFCA) and inferiorly (from the ascending and transverse MFCA). Any surgical hip intervention should preserve the posterior FCA, and lateral and medial RW in order to preserve the FH vascular supply. These results illustrate a vascular danger zone that should be respected during surgery and can be easily interpreted with the commonly used clock face

The femoral head receives its blood supply primarily from the medial femoral circumflex artery, with its deep branch being the most important. In a previous study, we performed classical anatomical dissections of 16 hips. We have extended our investigation with a radiological study, in which we aimed to visualise the arteries supplying the femoral head in healthy individuals. We analysed 55 CT angiographic images of the hip. Using 64-row CT angiography, we identified three main arteries supplying the femoral head: the deep branch of the medial femoral circumflex artery and the posterior inferior nutrient artery originating from the medial femoral circumflex artery, and the piriformis branch of the inferior gluteal artery. CT angiography is a good method for visualisation of the arteries supplying the femoral head. The current radiological studies will provide information for further investigation of vascularity after traumatic dislocation of the hip, using CT angiography

The femoral head receives blood supply mainly from the deep branch of the medial femoral circumflex artery (MFCA). In previous studies we have performed anatomical dissections of 16 specimens and subsequently visualised the arteries supplying the femoral head in 55 healthy individuals. In this further radiological study we compared the arterial supply of the femoral head in 35 patients (34 men and one woman, mean age 37.1 years (16 to 64)) with a fracture/dislocation of the hip with a historical control group of 55 hips. Using CT angiography, we identified the three main arteries supplying the femoral head: the deep branch and the postero-inferior nutrient artery both arising from the MFCA, and the piriformis branch of the inferior gluteal artery. It was possible to visualise changes in blood flow after fracture/dislocation. Our results suggest that blood flow is present after reduction of the dislocated hip. The deep branch of the MFCA was patent and contrast-enhanced in 32 patients, and the diameter of this branch was significantly larger in the fracture/dislocation group than in the control group (p = 0.022). In a subgroup of ten patients with avascular necrosis (AVN) of the femoral head, we found a contrast-enhanced deep branch of the MFCA in eight hips. Two patients with no blood flow in any of the three main arteries supplying the femoral head developed AVN. Cite this article: Bone Joint J 2013;95-B:1453–7

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

Aims

We aimed to quantify the relative contributions of the medial femoral circumflex artery (MFCA) and lateral femoral circumflex artery (LFCA) to the arterial supply of the head and neck of the femur.

This study investigates and defines the topographic anatomy of the medial femoral circumflex artery (MFCA) terminal branches supplying the femoral head (FH). Gross dissection of 14 fresh–frozen cadaveric hips was undertaken to determine the extra and intracapsular course of the MFCA’s terminal branches. A constant branch arising from the transverse MFCA (inferior retinacular artery; IRA) penetrates the capsule at the level of the anteroinferior neck, then courses obliquely within the fibrous prolongation of the capsule wall (inferior retinacula of Weitbrecht), elevated from the neck, to the posteroinferior femoral head–neck junction. This vessel has a mean of five (three to nine) terminal branches, of which the majority penetrate posteriorly. Branches from the ascending MFCA entered the femoral capsular attachment posteriorly, running deep to the synovium, through the neck, and terminating in two branches. The deep MFCA penetrates the posterosuperior femoral capsular. Once intracapsular, it divides into a mean of six (four to nine) terminal branches running deep to the synovium, within the superior retinacula of Weitbrecht of which 80% are posterior. Our study defines the exact anatomical location of the vessels, arising from the MFCA and supplying the FH. The IRA is in an elevated position from the femoral neck and may be protected from injury during fracture of the femoral neck. We present vascular ‘danger zones’ that may help avoid iatrogenic vascular injury during surgical interventions about the hip. Cite this article: Bone Joint J 2015;97-B:1204–13

We performed a series of 16 anatomical dissections on Caucasian cadaver material to determine the surgical anatomy of the medial femoral circumflex artery (MFCA) and its anastomoses. These confirmed that the femoral head receives its blood supply primarily from the MFCA via a group of posterior superior nutrient arteries and the posterior inferior nutrient artery. In terms of anastomoses that may also contribute to the blood supply, the anastomosis with the inferior gluteal artery, via the piriformis branch, is the most important. These dissections provide a base of knowledge for further radiological studies on the vascularity of the normal femoral head and its vascularity after dislocation of the hip

Introduction:. A surgical hip dislocation provides circumferential access to the femoral head and is essential in the treatment pediatric and adult hip disease. Iatrogenic injury to the femoral head blood supply during a surgical may result in the osteonecrosis of the femoral head. In order to reduce vessel injury and incidence of AVN, the Greater Trochanteric Osteotomy (GTO) was developed and popularized by Ganz. The downside of this approach is the increased morbidity associated with the GTO including non-union in 8% and painful hardware requiring removal in 20% of patients. (reference) Recent studies performed at our institution have mapped the extra-osseous course of the medial femoral circumflex artery and provide surgical guidelines for a vessel preserving posterolateral approach. In this cadaveric model using Gadolinium enhanced MRI, we investigate whether standardized alterations in the postero-lateral surgical approach may reliably preserve femoral head vascularity during a posterior surgical hip dislocation. Methods:. In 8 cadaveric specimens the senior author (ES) performed a surgical hip dislocation through the posterolateral approach with surgical modifications designed to protect the superior and inferior retinacular arteries. In every specimen the same surgical alterations were made using a ruler: the Quadratus Femoris myotomy occurred 2.5 cm off its trochanteric insertion, the piriformis tenotomy occurred at its insertion and extended obliquely leaving a 2 cm cuff of conjoin tendon (inferior gemellus), and the Obturator Externus (OE) was myotomized 2 cm off its trochanteric insertion. (Figure 1) For the capsulotomy, the incision started on the posterior femoral neck directly beneath the cut obturator externus tendon and extending posteriorly to the acetabulum. Superior and inferior extensions of the capsulotomy ran parallel to the acetabular rim creating a T-shaped capsulotomy. After the surgical dislocation was complete, the medial femoral circumflex artery (MFCA) was cannulated and Gadolinium-enhanced MRI performed in order to assess intra-osseous femoral head perfusion and compared to the gadolinium femoral head perfusion of the contra-lateral hip as a non-operative control. Gross-dissection after polyurethane latex injection in the cannulated MFCA was performed to validate MRI findings and to assess for vessel integrity after the surgical dislocation. Results:. In 8 cadaveric specimens MRI quantification of femoral head perfusion was 94.3% and femoral head-neck junction perfusion was 93.5% compared to the non-operative control. (Figure 2) Gross dissection after latex injection into the MFCA demonstrated intact superior and inferior retinacular arteries in all 8 specimens. (Figure 3). Discussion and Conclusions:. In this study, perfusion to the femoral head and head-neck junction is preserved following posterior surgical dislocation through the postero-lateral approach. These preliminary findings suggest that specific surgical modifications can protect and reliably maintain vascularity to the femoral head after surgical hip dislocation. This approach may benefit hip resurfacing and potentially decease risk of femoral neck fracture secondary to osteonecrosis. In addition this may allow a vascular preserving surgical hip dislocation to be performed without the need for a GTO

We used laser Doppler flowmetry (LDF) with a high energy (20 mW) laser to measure perfusion of the femoral head intraoperatively in 32 hips. The surgical procedure was joint debridement requiring dislocation or subluxation of the hip. The laser probe was placed within the anterosuperior quadrant of the femoral head. Blood flow was monitored in specific positions of the hip before and after dislocation or subluxation. With the femoral head reduced, external rotation, both in extension and flexion, caused a reduction of blood flow. During subluxation or dislocation, it was impaired when the posterosuperior femoral neck was allowed to rest on the posterior acetabular rim. A pulsatile signal returned when the hip was reduced, or was taken out of extreme positions when dislocated. After the final reduction, the signal amplitudes were first slightly lower (12%) compared with the initial value but tended to be restored to the initial levels within 30 minutes. Most of the changes in the signal can be explained by compromise of the extraosseous branches of the medial femoral circumflex artery and are reversible. Our study shows that LDF provides proof for the clinical observation that perfusion of the femoral head is maintained after dislocation if specific surgical precautions are followed

Surgical dislocation of the hip is rarely undertaken. The potential danger to the vascularity of the femoral head has been emphasised, but there is little information as to how this danger can be avoided. We describe a technique for operative dislocation of the hip, based on detailed anatomical studies of the blood supply. It combines aspects of approaches which have been reported previously and consists of an anterior dislocation through a posterior approach with a ‘trochanteric flip’ osteotomy. The external rotator muscles are not divided and the medial femoral circumflex artery is protected by the intact obturator externus. We report our experience using this approach in 213 hips over a period of seven years and include 19 patients who underwent simultaneous intertrochanteric osteotomy. The perfusion of the femoral head was verified intraoperatively and, to date, none has subsequently developed avascular necrosis. There is little morbidity associated with the technique and it allows the treatment of a variety of conditions, which may not respond well to other methods including arthroscopy. Surgical dislocation gives new insight into the pathogenesis of some hip disorders and the possibility of preserving the hip with techniques such as transplantation of cartilage

Femoral neck fractures remain the leading cause of early failure after metal-on-metal hip resurfacing. Although its' exact pathomechanism has yet to be fully elucidated, current retrieval analysis has shown that either an osteonecrotic event and/or significant surgical trauma to the femoral head neck junction are the leading causes. It is most likely that no single factor like patient selection and/or femoral component orientation can fully avoid their occurrence. As in osteonecrosis of the native hip joint, a certain cell injury threshold may have to be reached in order for femoral neck fracture to occur. These insults are not limited to the surgical approach, but also include femoral head preparation, neck notching, and cement penetration. Although some have argued that the posterior approach does not represent an increased risk fracture for ON after hip resurfacing because of the so-called intraosseous blood supply to the femoral head, to date, the current body of literature on femoral head blood flow in the presence of arthritis has confirmed the critical role of the extraosseous blood supply from the ascending branch of the medial circumflex, as well as the lack of any substantial intraosseous blood supply. Conversely, anterior hip dislocation of both the native hip joint as well as the arthritic hip preserves femoral head vascularity. The blood supply can be compromised by either sacrificing the main branch of the ascending medial femoral circumflex artery or damaging the retinacular vessels at the femoral head-neck junction. Thus an approach which preserves head vascularity, while minimizing soft tissue disruption would certainly be favorable for hip resurfacing. This presentation will review the current state of knowledge on vascularity of the femoral head as well as surgical techniques enhancing its preservation

Introduction: Dividing the short external rotators 2 cm from their insertion into the femur should preserve the deep branch of the medial femoral circumflex artery. Our aim was to determine, prospectively, femoral head perfusion during hip resurfacing arthroplasty comparing two posterior approaches. Methods: 20 hip resurfacing arthroplasties were performed in 20 patients by two different surgeons between September 2005 and November 2006. Patients were divided into two equal groups according to approach. One surgeon used the extended posterior approach and the other a modified posterior approach. Intravenous cefuroxime was administered in every case following capsulectomy and relocation of the femoral head. After 5 minutes the femoral head was dislocated and prepared as routine for the operation. Bone from the top of the femoral head and reamings were sent for assay to determine the concentration of cefuroxime. Results: There was no statistical difference between the concentration of cefuroxime in bone when using the modified posterior approach (mean 5.6mg/kg; CI 3.6 – 7.8) compared to the extended posterior approach (mean 5.6; CI 3.5 – 7.8; p=0.95). In one patient, who had the operation through the posterior approach, cefuroxime was undetectable. Discussion: The similarity in femoral head perfusion between approaches suggests the blood supply is further impaired by capsulectomy rather than by damaging the MFCA alone

Introduction: Two major complications of hip resurfacing arthroplasty are avascular necrosis of the femoral head and femoral neck fracture. Both are thought to be precipitated by disruption of the blood supply to the femoral head and neck during the approach to the hip joint. Ganz et al have described their technique of approaching the hip joint using a “trochanteric flip” osteotomy. This has the theoretical advantage of preserving the medial femoral circumflex artery to the femoral head. The aim of this study was to compare the intra-operative femoral head blood flow during the Ganz flip osteotomy to the blood flow during a posterior approach for resurfacing arthroplasty of the hip. Methods: The intra-operative measurements of blood flow were performed using a DRT laser Doppler flow-meter with a 20 mW laser and a fibreoptic probe. The probe was introduced into the lateral femoral cortex and threaded into the femoral head under image intensifier control. Measurements were recorded before the approach to the hip was performed, after the approach was performed but before the head was dislocated, and after the head was dislocated. Results: Our initial results indicate that there is on average a 50% drop in the blood flow to the femoral head after a posterior approach to the hip joint. In contrast, the trochanteric flip osteotomy produces a much smaller fall of around 18%. We have used these results to inform a sample size calculation, and are currently recruiting further patients to achieve a total of 42 in order to confirm a statistically significant effect. Conclusion: The Ganz trochanteric flip osteotomy appears to produce less damage to the blood supply to the femoral head during resurfacing arthroplasty than the posterior approach. This study will inform surgeons in deciding on their preference for a routine approach for hip resurfacing

Introduction. The vascular anatomy of the femoral head and neck has been previously reported, with the primary blood supply attributed to the deep branch of the Medial Femoral Circumflex Artery (MFCA). This understanding has led to development of improved techniques for surgical hip dislocation for multiple intra-capsular hip procedures including Hip Resurfacing Arthroplasty (HRA). However, there is a lack of information in the literature on quantitative analysis of the contributions of the Lateral Femoral Circumflex Artery (LFCA) to femoral head and neck. Additionally, there is a lack of detailed descriptions in the literature of the anatomic course of the LFCA from its origin to its terminal branches. Materials & Methods. Twelve fresh-frozen human pelvic cadaveric specimens were studied (mean age 54.3 years, range 28–69). One hip per specimen was randomly assigned as the experimental hip, with the contralateral used as a control. Bilateral vascular dissection was performed to cannulate the MFCA and LFCA. Specimens were assigned as either LFCA-experimental or MFCA-experimental. All specimens underwent a validated quantitative-MRI protocol: 2mm slice thickness with pre- and post- MRI contrast sequences (Gd-DTPA diluted with saline at 3:1). In the LFCA-experimental group 15ml of MRI contrast solution was injected into the LFCA cannula. In the MFCA-experimental group 15ml of contrast solution was injected into the MFCA cannula. On the control hip contrast solution was injected into both MFCA and LFCA cannulas, 15ml each (30ml total for the control hip). Following MRI, the MFCA and LFCA were injected with polyurethane compound mixed with barium sulfate (barium sulfate only present in either MFCA or LFCA on each hip). Once polymerization had occurred, hips underwent thin-slice CT scan to document the extra- and intra-capsular course of the LFCA and MFCA. Gross dissection was performed to visually assess all intra-capsular branches of both the MFCA and LFCA and assess for extravasation. Quantitative-MRI analysis was performed based on Region of Interest (ROI) assessment. Femoral heads were osteotomized at the level of the largest diameter proximal to the articular margin and perpendicular to the femoral neck, for placement of a 360° scale. Measurements using the 360° scale were recorded. For data processing, we used right-side equivalents and integrated our 360° data into the more commonly used imaginary clock face. Results. Quantitative analysis of contributions of the MFCA and LFCA are detailed (Table 1). Thin slice CT scan graphical analysis of the LFCA provided (Figure 1). Topographic 360° scale (and imaginary clock face) results are also detailed in a diagram (Figure 2). Discussion. This study provides the first comparative results for quantitative assessment of arterial contributions from both the MFCA and LFCA for the femoral head and neck. The MFCA is the dominant vessel for both the femoral head and neck, supplying 82% of the femoral head and 67% of the femoral neck. The LFCA plays its largest role in the inferoanterior femoral neck (with a 48% arterial contribution). This finding highlights the importance of protecting the LFCA in addition to the MFCA during intra-capsular hip procedures including Hip Resurfacing Arthroplasty

Introduction: Whereas in traumatic avascular necrosis of the femoral head (ANFH) loss of the femoral head’s blood supply is due to a mechanical event, in non-traumatic AFNH it is the result of a wide variety of etiologies (e.g. alcoholism, hypercortisonism, etc.), which have in common that they lead to an intravascular complication with subsequent malperfusion of the femoral head. Additionally, for part of non-traumatic ANFH no causative factors are known, why they are called idiopathic. A mechanical cause for nontraumatic ANFH – as e.g. a repetitive trauma of the femoral head supplying deep branch of the medial femoral circumflex artery and its terminal branches by abutment of the femur against the acetabulum as in femoroacetabular impingement (FAI) – has not been discussed so far. Methods: The anteroposterior and lateral radiographs of 118 hips in 77 patients, who were operated in our institution between January 1995 and December 2005 because of nontraumatic ANFH, were evaluated with respect to the configuration of the head-neck junction. In a qualitative analysis the head-neck contour of all femora was assigned to one of the following four groups: regular waisting, mildly reduced waisting, reduced to distinctly reduced waisting or completely lacking waisting. In a quantitative analysis, angle alpha according to Nötzli et al. (2002) was measured. Furthermore, the CCD angle was measured to assess the orientation of the femoral neck in the frontal plane as well as the LCE-angle according to Wiberg and the acetabular index of the weightbearing zone to rule out any acetabular anomalies. Results: In this retrospective analysis, for 44.1% of the hip joints hypercortisonism, for 40.7% alcoholism, for 12.7% hypercholesterinemia and for 11.0% no risk factors were found documented in the patients’ files. In AP and lateral radiographs a regular waisting was found in 60.2% and 9.3%, a mildly reduced waisting in 32.2% and 37.3%, a reduced waisting or distinctly reduced waisting in 7.6% and 35.6%, and a completely lacking waisting in 0% and 16.9%, respectively, and the mean angle alpha was 63° ± 18° and 67° ± 14°, respectively. On average, the (frontally projected) CCD angle was 133° ± 6°, the LCE angle 30° ± 7° and the acetabular index of the weightbearing zone 4° ± 5°. Conclusion: Nötzli et al. found an angle alpha of 42° ± 2° for healthy individuals. A markedly increased angle alpha in both radiographic planes of the 118 investigated hips with nontraumatic ANFH was found, demonstrating a reduced shape of their head-neck junction in the anterior and lateral aspect. Together with the fact that no gross pathological deviations for the orientation of the femoral neck and the acetabulum were found, this may hint at cam-type FAI to occur in this hips and thus potentially at a mechanical (co-) factor in developing non-traumatic ANFH

Aims

Avascular femoral head necrosis in the context of gymnastics is a rare but serious complication, appearing similar to Perthes’ disease but occurring later during adolescence. Based on 3D CT animations, we propose repetitive impact between the main supplying vessels on the posterolateral femoral neck and the posterior acetabular wall in hyperextension and external rotation as a possible cause of direct vascular damage, and subsequent femoral head necrosis in three adolescent female gymnasts we are reporting on.

Aims

Surgical approaches that claim to be minimally invasive, such as the direct anterior approach (DAA), are reported to have a clinical advantage, but are technically challenging and may create more injury to the soft-tissues during joint exposure. Our aim was to quantify the effect of soft-tissue releases on the joint torque and femoral mobility during joint exposure for hip resurfacing performed via the DAA.