Despite recent advances in the management of slipped capital femoral epiphysis (SCFE), controversy remains about the treatment of choice for unstable slips. Surgical dislocation and open reduction has the advantage of identifying and preserving the blood supply of femoral head thereby potentially reducing the risk of avascular necrosis, (AVN). There is large variation in the literature from several small series about reported AVN rates ranging from two to 66% for unstable SCFE treated with surgical dislocation. The aim of our study was to analyze our experience with acute open reduction and internal fixation of unstable acute and unstable acute on chronic slips using the technique of surgical dislocation described by Professor Reinhold Ganz. A retrospective review of 11 patients (12 hips) treated by surgical dislocation, reduction and pinning as the primary procedure for unstable acute and unstable acute on chronic SCFE in a tertiary referral children's hospital was undertaken. This represents the entire series treated in this manner from September 2007 to January 2018. These procedures were performed by a team of Orthopaedic surgeons with significant experience performing surgical dislocation of the hip including patients with chronic SCFE, Perthes' disease, impingement and acetabular fractures. Demographic data, intraoperative records, postoperative notes and radiographs including details of subsequent surgery were reviewed. There were seven boys and four girls with mean age of 13.4 years, range 11 to 15 years at the time of surgical dislocation. Out of 12 hips, two had acute unstable slip while the remaining 10 had acute on chronic unstable slip. Six patients had good or excellent results. The remaining six patients developed AVN of which three patients had total hip replacement at six months, 17 months and 18 months following primary procedure. Seven patients required more than one operation. Three patients lost their correction and required re fixation despite surgical dislocation, reduction and fixation being their primary procedure. This series demonstrates a high percentage of AVN (50%) in severe unstable SCFE treated with surgical dislocation despite careful attention to retinacular flap development and intra operative doppler studies. This is in direct contrast to our experience with subcapital reorientation with surgical dislocation in stable slips where excellent results were achieved with a low rate of AVN. Pre-operative imaging with MRI and perfusion studies may identify where ischemia has occurred and might influence operative treatment. Based on our results, we do not recommend routine use of surgical dislocation in unstable SCFE. This technique requires further scrutiny to define the operative indications in unstable SCFE

Surgical treatment options for Femoroacetabular impingement (FAI) includes both surgical dislocation and hip arthroscopy techniques. The primary aim of this study was to evaluate and compare the survivorship of arthroscopies (scope) and surgical dislocations (SD) at minimum 5-year follow-up. The secondary aim was to describe differences in functional outcomes between the 2 groups. This was a retrospective, single surgeon, consecutive, case-series from a large tertiary care centre. We evaluated all surgeries that were performed between 2005 and 2011. Our institutional database was queried for any patient undergoing surgery for FAI (pincer (n=23), cam (n=306), or mixed (n=103) types). Patients with childhood pathologies i.e. Legg Calve Perthes and slipped capital femoral epiphysis were excluded. This resulted in 221 hips (169 males, 52 females) who underwent either SD (94, 42.5%) or scope (127, 57.5%). A manual chart review was completed to identify patients who sustained a complication, underwent revision surgery or progressed to a total hip arthroplasty (THA). In addition, we reviewed prospectively collected patient reported outcome measure (PROMs) using (SF12, HOOS, and UCLA). Survivorship outcome was described for the whole cohort and compared between the 2 surgical groups. PROMs between groups were compared using The Mann-Whitney U test and the survival between groups was assessed using the Kaplan-Meier Analysis and the Log-Rank Mantel Cox test. All analyses were performed in SPSS (IBM, v. 26.0). The cohort included 110 SDs and 320 arthroscopies. The mean age of the whole cohort was 34±10; patients in the SD group (32±9) were younger compared to the arthroscopy group (39±10) (p<0.0001). There were 16 post-operative complications (similar between groups) and 77 re-operations (more common in the SD group (n=49) due to symptomatic metal work (n=34)). The overall 10-year survival was 91±3%. Survivorship was superior in the arthroscopy group at both 5- (96% (95%CI: 93 – 100)) and 8- years 94% (95%CI: 90 – 99%) compared to the SD Group (5-yr: 90% (95%CI: 83 – 98); 8-yr: 84% (95%CI:75 – 93)) (p=0.003) (Figure 1). On average HOOS improved from 54±19 to 68±22 and WOMAC from 65±22 to 75±22. The improvement in PROMs were similar between the 2 groups. We report very good long-term joint preservation for the treatment of FAI, which is similar to those reported in hip dysplasia. In addition, we report satisfactory improvement in function following such treatment. The differences reported in joint survival likely reflect selection biases from the treating surgeon; more complex cases and those associated with more complex anatomy were more likely to have been offered a SD in order to address the pathology with greater ease and hence the inferior joint preservation identified in this group. For any figures or tables, please contact the authors directly

Introduction. We present a single surgeon series of 20 modified Dunn osteotomies without surgical dislocation of the femoral head for slipped upper femoral epiphysis (SUFE). Method. All patients from 2007 to 2011 who had a Dunn osteotomy for SUFE had their notes reviewed and we obtained an updated Non Arthritic Hip Score. Results. 20 patients were identified, of which 5 were female, with a combined average age of 14. The average duration of symptoms prior to the procedure was 10.2 weeks (range, 4–78). Classifications divided the cases into 7 chronic slips, 7 acute-on-chronic, and 5 acute., and 7 of the cases were unstable slips with an average slip angle of 71 degrees (range 65–85). All slips were grade 3. Average follow up was 26.2 months (range, 2–62). 3 developed avasular necrosis (2 unstable, 1 stable) and 2 patients had symptomatic leg length discrepancy. Preoperative MRI scans were performed in 4 patients and showed vascular compromise, but this did not always correlate with intraoperative findings of avascularity when the head was drilled. The average Nonarthritic hip score was 71.6 (range, 60–80). Summary. Dunn osteotomies are safe in patients with chronic slips, and have a low incidence of AVN. Overall function was good, even in those patients with segmental AVN scoring highly on their hip scores. Keeping the ligamentum teres intact and not dislocating the femoral head may improve vascularity of the head. Vascularity may also be assessed by preoperative MRI scans, although radiological suggestion of an avascular head which contradicted clinical findings and postoperative outcome may be due to transient vessel spasm

Objective

To define the common pathology of the hips with irreducible posterior dislocation combined with femoral head fracture and the outcome of surgical treatment using surgical hip dislocation technique.

Design: retrospective observational clinical study

Setting: Level III referral trauma center

Patients/Participants: from January 2011till February 2014 five patients with irreducible posterior hip dislocation and femoral head fracture who underwent operation were included and they followed for at least 18 months.

Arthrosis of the hip joint can be a significant source of pain and dysfunction. While hip replacement surgery has emerged as the gold standard for the treatment of end stage coxarthrosis, there are several non-arthroplasty management options that can help patients with mild and moderate hip arthritis. Therefore, the purpose of this paper is to review early prophylactic interventions that may help defer or avoid hip arthroplasty. Nonoperative management for the symptomatic hip involves minimizing joint inflammation and maximizing joint mobility through intra-articular joint injections and exercise therapy. While weight loss, activity modifications, and low impact exercises is generally recommended for patients with arthritis, the effects of these modalities on joint strength and mobility are highly variable. Intra-articular steroid injections tended to offer reliable short-term pain relief (3–4 weeks) but provided unreliable long-term efficacy. Additionally, injections of hyaluronic acid do not appear to provide improved pain relief compared to other modalities. Finally, platelet rich plasma injections do not perform better than HA injections for patients with moderate hip joint arthrosis. Primary hip joint arthrosis is rare, and therefore treatment such as peri-acetabular osteotomies, surgical dislocations, and hip arthroscopy and related procedures are aimed to minimise symptoms but potentially aim to alter the natural history of hip diseases. The state of the articular cartilage at the time of surgery is critical to the success or failure of any joint preservation procedures. Lech et al. reported in a series of dysplastic patients undergoing periacetabular osteotomies that one third of hips survived 30 years without progression of arthritis or conversion to THA. Similarly, surgical dislocation of the hip, while effective for treatment of femoroacetabular impingement, carries a high re-operation rate at 7 years follow up. Finally, as the prevalence of hip arthroscopic procedures continues to rise, it is important to recognise that failure to address the underlying structural pathologies can lead to failure and rapid joint destruction. In summary, several treatment modalities are available for the management of hip pain and dysfunction in patients with a preserved joint space. While joint preservation procedures can help improve pain and function, they rarely alter the natural history of hip disease. The status of the articular cartilage at the time of surgery is the most important predictor of treatment success or failure

Purpose. Surgical dislocation is useful for assessing and treating proximal femoral hip deformities. Legg-Calv Perthes disease (LCPD) causes proximal femoral growth deformity, resulting in reduced femoral head-neck offset and femoracetabular incongruity. The purpose of this study was to demonstrate the efficacy and report the short-term results of surgical hip dislocation for the treatment of adolescents with healed LCPD. Method. This retrospective review included 29 adolescents [19 males and 10 females, age 17 (range nine-35)] with LCPD, who underwent surgical hip dislocation between January 2001 and December 2009. All subjects had a clear diagnosis of LCPD, pre and postoperative WOMAC scores and at least one year of clinical and radiographic follow up. In addition to surgical dislocation, all patients underwent femoral head-neck osteoplasty, 21 underwent relative femoral neck lengthening and trochanteric transfer, 12 underwent intertrochanteric osteotomy and seven had labral debridement. The average follow-up was three years from the time of surgical intervention. Results. Postoperative WOMAC scores improved globally for pain, stiffness and function (p<0.0001, p<0.0004 and p<0.0009 respectively). Eight patients required additional surgical procedures after surgical dislocation (one periacetabular osteotomy, one flexion intertrochanteric osteotomy, one arthrotomy, five arthroscopies with labral/cartilage debridement. Three patients underwent total hip arthroplasties during the follow-up period and were considered failures. Two of the 29 patients experienced superficial wound complications. Conclusion. Surgical dislocation is an effective technique for the treatment of proximal femur deformity associated with LCPD. In the short-term, patients experience improved symptoms and function from this procedure

Over the past fifteen years hip preservation surgery has rapidly evolved. Improved understanding of the pathomechanics and associated intra-articular degeneration of both hip instability and femoroacetabular impingement have led to improved surgical indications, refined surgical techniques and more effective joint preservation surgical procedures. The periacetabular osteotomy (PAO) was initially introduced by Ganz and colleagues and has become the preferred treatment in North America for pre-arthritic, symptomatic acetabular dysplasia. Both hip arthroscopy and safe surgical dislocation of the hip have been popularised for the treatment of symptomatic femoroacetabular impingement disorders. Hip arthroscopy is effective for focal and\or accessible impingement lesions while the surgical dislocation approach is reserved for nonfocal disease patterns as seen in complex FAI, and residual Perthes and SCFE deformities. Femoroacetabular impingement from major acetabular retroversion can be managed with the PAO if there is coexistent posterosuperior acetabular insufficiency. Short- to mid-term results of these procedures are generally good to excellent for most patients and the complication rates associated with these procedures are very acceptable. Long-term outcomes are best known for the PAO. Several recent studies have documented survivorship rates of 65–90% at 10–20-year follow-up. Certain factors are associated with long-term success including minimal pre-operative radiographic OA, early symptoms, accurate acetabular correction, and younger age. These data strongly suggest that the PAO can defer THA to an older age for most patients while completely avoiding arthroplasty may only be possible in select patients with excellent congruency, no secondary OA and an ideal surgical correction

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

The majority of patients who develop hip arthritis have a mechanical abnormality of the joint. The structural abnormalities range from instability (DDH) to impingement. Impingement leads to osteoarthritis by chronic damage to the acetabular labrum and adjacent cartilage. In situations of end-stage secondary DJD, hip arthroplasty is the most reliable treatment choice. In young patients with viable articular cartilage, joint salvage is indicated. Treatment should be directed at resolving the structural abnormalities that create the impingement. Femoral abnormalities corrected by osteotomy or increased head-neck offset by chondro-osteoplasty creating a satisfactory head-neck offset. This can safely be done via anterior surgical dislocation. The acetabular-labral lesions can be debrided and/or repaired. Acetabular abnormalities should be corrected by “reverse” PAO in those with acetabular retroversion or anterior acetabular debridement in those with satisfactory posterior coverage and a damaged anterior rim. Often combinations of the above are indicated

This case series highlights the use of the Ganz approach (trochanteric slide approach) and surgical dislocation for excision of fibrous dysplasia of the femoral neck, pigmented villonodular synovitis and synovial chondromatosis of the hip. The first patient was a 16-year-old girl, who presented with pain in her hip, having fallen whilst playing football. Investigations revealed a fibrous dysplasia, which was successfully excised returning her to an active lifestyle. The second patient was a 27-year-old lady, who presented having suffered left hip pain for four years. She was diagnosed with a pigmented villonodular synovitis, which was excised and the patient was able to return to the gym. The third patient was a 41-year-old lady, who presented after experiencing right hip pain both at night and at rest for a year, without any trauma. She was diagnosed with synovial chondromatosis and returned to all activities of daily living. The Ganz approach allows safe dislocation of the hip joint without the risk of osteonecrosis of the femoral head. We demonstrate that it is possible to obtain excellent exposure of the femoral neck, head and acetabulum to surgically treat these three tumours of the hip. The surgeon can thus be reassured that complete excision of the tumour has occurred. This series can recommend the Ganz approach with trochanteric slide and full surgical dislocation of the hip to excise pigmented villonodular synovitis, synovial chondromatosis and fibrous dysplasia of the hip

Economic data, clinical outcome studies, and anatomical studies continue to support the Superior Hip Approach as a preferred approach for improved safety, maximal tissue preservation, rapid recovery, and minimised cost. Clinical studies show exceedingly low rates of all major complications including femur fracture, dislocation, and nerve injury. Economic data from Q1 2013 to Q2 2016 demonstrate that CMS-insured patients treated by the Superior Hip Approach have the lowest cost of all patients treated in Massachusetts by an average of more than $7,000 over 90 days. The data show that the patients treated by the Superior Hip Approach have lower cost than any other surgical technique. Matched-pair bioskills dissections demonstrate far better preservation of the hip joint capsule and short external rotators than the anterior approach. Design principles include: Preservation of the abductors; Preservation of the posterior capsule and short external rotators; Preparation of the femur in situ prior to femoral neck osteotomy; Excision of the femoral head, thereby avoiding surgical dislocation of the hip; In-line access to the femoral shaft axis; Ability to perform a trial reduction; Independence from intra-operative imaging; Independence from a traction table; Applicable to at least 99% of THA procedures. Conclusion. In contrast to the results of the Superior Approach, the anterior approach continues to show difficulties with wound problems, infection, intra- and post-operative fracture, and failure of femoral component osseointegration and even dislocation. Evidence continues to demonstrate that the Superior Hip Approach has advantages over all other surgical approaches to the hip

The parameters to be considered in the selection of a cartilage repair strategy are: the diameter of the chondral defect; the depth of the bone defect; the location of the defect (weight bearing); alignment. A chondral defect less than 3 cm in diameter can be managed by surface treatment such as microfracture, autologous chondrocyte transplantation, mosaicplasty, or periosteal grafting. An osteochondral defect less than 3 cm in diameter and less than 1 cm in depth can be managed by autologous chondrocyte transplantation, mosaicplasty or periosteal grafting. An osteochondral defect greater than 3 cm in diameter and 1 cm in depth is best managed by an osteochondral allograft. If there is an associated knee deformity, then an osteotomy should also be performed with all of the aforementioned procedures. In our series of osteochondral allografts for large post-traumatic knee defects realignment osteotomy is performed about 60% of the time in order to off load the transplant. To correct varus we realign the proximal tibia with an opening wedge osteotomy. To correct valgus, we realign the distal femur with a closing wedge osteotomy. Our results with osteochondral allografts for the large osteochondral defects of the knee have been excellent in 85% of patients at an average follow-up of 10 years. The Kaplan-Meier survivorship at 15 years is 72%. At an average follow-up of 22 years in 58 patients with distal femoral osteochondral allograft, 13 have been revised (22%). The 15-year survivorship was 84%. The results for the hip are early. To date we have performed this procedure on 16 patients. Surgical dislocation of the hip is carried out via a trochanteric osteotomy and the defect defined and trephined out. A press-fit fresh osteochondral allograft is inserted using the trephine technique. We have published our early results on a series of 8 patients with 5 good to excellent results, 1 fair result and 2 failures

The majority of patients who develop hip arthritis have a mechanical abnormality of the joint. The structural abnormalities range from instability (DDH) to impingement. Impingement leads to osteoarthritis by chronic damage to the acetabular labrum and adjacent cartilage. In situations of endstage secondary DJD, hip arthroplasty is the most reliable treatment choice. In young patients with viable articular cartilage, joint salvage is indicated. Treatment should be directed at resolving the structural abnormalities that create the impingement. Femoral abnormalities corrected by osteotomy or increased head-neck offset by chondro-osteoplasty creating a satisfactory head-neck offset. This can safely be done via anterior surgical dislocation. The acetabular-labral lesions can be debrided and/or repaired. Acetabular abnormalities should be corrected by “reverse” PAO in those with acetabular retroversion or anterior acetabular debridement in those with satisfactory posterior coverage and a damaged anterior rim. Often combinations of the above are indicated. This talk will also update issues related to hip impingement and joint salvage surgery that have arisen over the past year

Cervical bifacet dislocations are devastating injuries and require early reduction and surgical stabilization. Closed reduction is safe and neurological deterioration is rare. Pre-reduction MRI can cause clinical uncertainty as to the safety of closed reduction when a significant sequestrated disc is found. This study explores the direct cord pressures in a bifacet dislocation model with the use of fresh frozen cadaver cervical spines and a Tekscan Pressure Measurement System. Method. Surgical dislocations were created and pressure monitors inserted into the canal. Pressures on the cord from the posterior-superior edge of the caudal body as well as that from the cranial body were assessed at the level of the dislocation. The effects of the presence of a disc and its size, reduction angles and level of dislocation before and during closed reduction were evaluated. Results. The average dislocated spinal cord pressures were measured at 3.81 kPa and increased to 20.22 kPa under traction. This decreased to 1.295 kPa after cervical spine reduction. Average cord pressures as well as peak loading pressures were shown to increase with the increasing size of the prolapsed disc and diminished once the spine was reduced. Conclusion. This model provides additional insight into cervical spine dislocation and the contribution of disc prolapse to cord injury. NO DISCLOSURES

Peri-prosthetic fractures of the femur around a THA remain challenging injuries to treat. The Vancouver Classification helps to guide decision making, and is based on fracture location, implant fixation status, and remaining bone quality. It is critical to determine fixation status of the implant, even if surgical dislocation is necessary. Type A fractures involve the trochanters, and are usually due to osteolysis. Revision of the bearing surface and bone grafting of the lesions can be effective. Type B1 fractures occur around a well fixed stem, typically at the stem tip. Internal fixation with laterally based locked cable plates is effective. Optimising proximal fixation is important, typically with locked screws and cables. Allograft struts are probably unnecessary with modern angle stable plates. Type B2 and B3 fractures are treated with revision, either with a fully coated cylindrical or a modular fluted tapered titanium stem. Distal fixation should be optimised, while preserving vascularity to proximal bony fragments. The « internal scaffold » technique has been described with excellent results. Rarely, a proximal femoral replacement is necessary. Careful attention to detail and clear knowledge of stem fixation status is necessary for a good outcome

The majority of patients who develop hip arthritis have a mechanical abnormality of the joint. The structural abnormalities range from instability (DDH) to impingement. Impingement leads to osteoarthritis by chronic damage to the acetabular labrum and adjacent cartilage. In situations of endstage secondary DJD, hip arthroplasty is the most reliable treatment choice. In young patients with viable articular cartilage, joint salvage is indicated. Treatment should be directed at resolving the structural abnormalities that create the impingement. Femoral abnormalities corrected by osteotomy or increased head-neck offset by chondro-osteoplasty creating a satisfactory head-neck offset. This can safely be done via anterior surgical dislocation or arthroscopically. The acetabular-labral lesions can be debrided and/or repaired. Acetabular abnormalities should be corrected by “reverse” PAO in those with acetabular retroversion or anterior acetabular debridement in those with satisfactory posterior coverage and a damaged anterior rim. Often combinations of the above are indicated

Cartilage repair strategies have been applied successfully to the knee, but only recently and with limited experience to the hip. The indications for these strategies have been well defined for the knee and are defined by the diameter and depth of the defects that are mainly post traumatic and degenerative. Viscosupplementation is an intra-articular therapy that theoretically restores the protective effects of hyaluronic acid. This therapy has been widely used for osteoarthritis of the knee with some early preliminary promising results for osteoarthritis of the hip. Microfracture can be performed arthroscopically or as part of an open procedure. This procedure is indicated for smaller lesions less than 3cm in diameter and 1cm in depth. Widely used in the knee, the results in the hip are limited but promising. The repair tissue is however fibrocartilage. Autologous chondrocyte transplantation can yield hyaline like repair cartilage with good mid- to long-term results in the knee. The indications are chondral defects greater than 3cm in diameter or osteochondral defects less than 1cm in depth. Its use in the hip has been limited with only a few published papers. The procedure requires two stages. The first stage which involves harvesting the cartilage can be done arthroscopically, and the second stage which involves transplantation of the cultured chondrocytes can be done arthroscopically or open. Larger lesions greater than 3cm in diameter and 1cm in depth, can be managed by osteochondral allografts. The published mid- to long-term results for the knee have been encouraging. The results for the hip are early. To date we have performed this procedure on 16 patients. Surgical dislocation of the hip is carried out via a trochanteric osteotomy and the defect defined and trephined out. A press-fit fresh osteochondral allograft is inserted using the trephine technique. We have published our early results on a series of 8 patients with 5 good to excellent results, 1 fair results and 2 failures

Perthes disease often leaves young adults with hip joint incongruency due to femoral head asphericity, (extra-articular extrusion and superior flattening). This causes femoro-acetabular impingement, a reduced range of movement and early degenerative change. We report a novel method for restoration of femoral head sphericity and femoro-acetabular congruency. Two males (aged 21 and 22 years) presented with groin pain and severe hip stiffness after childhood Perthes disease. Imaging confirmed characteristic saddle shaped deformities of the femoral head, with cartilage loss overlying a central depression in the superior section of the head. A new method of treatment was proposed. Both cases were treated in the same manner. A surgical dislocation was performed with a trochanteric flip osteotomy. The extra-articular bump was removed with osteotomes and a burr to reduce femoro- acetabular impingement. The sphericity of the femoral head was restored using a HemiCap partial re-surfacing (Arthrosurface, MA, USA). The radius of the implant was selected to match that of the acetabulum. Restoration of the height of the flattened portion of the weight-bearing surface of the femoral head reduces abnormal loading of the acetabular articular cartilage by improving congruency of the joint. Both patients recovered without incident and were mobilised with crutches, restricted to touch weight-bearing for six weeks to protect union of the trochanteric osteotomy. At a minimum of three year follow-up both patients had sustained improved range of movement, pain and Oxford hip score. Repeated imaging shows no evidence of joint space narrowing or loosening at this stage. We conclude that this novel treatment functions well in the short term. Further surveillance is on-going to confirm that this treatment results in improved long term durability of the natural hip joint after Perthes disease

Protrusio acetabuli (arthrokatadysis or Otto pelvis) is a relatively rare condition associated with secondary osteoarthritis of the hip. Radiographically, protrusio acetabuli is present when the medial aspect of the femoral head projects medial to Kohler's (ilioischial) line. This results in medialization of the center of rotation (COR) of the hip. Protrusio acetabuli is typically associated with metabolic bone disease (osteoporosis, osteomalacia, Paget's disease) or inflammatory arthritis (RA or ankylosing spondylitis). Idiopathic acetabular protrusio can occur without the above associated factors however. Patients with protrusio acetabuli typically present with significant restriction of range of motion (ROM) of the hip due to femoral neck and trochanteric impingement in the deep acetabular socket and pain associated with secondary osteoarthritis (OA). Total hip arthroplasty (THA) in patients with protrusion acetabuli is more challenging than THA in patients with a normal hip COR. ROM is typically quite restricted which can compromise surgical exposure. Dislocation of the hip in the patient with a deep socket and medialised COR can be extremely difficult and associated with fracture of the femur if not carefully performed. Restoration of the hip COR to the normal more lateralised position is a principle goal of surgery. This restores more normal mechanics of the hip and has been associated with improved durability. A variety of techniques to accomplish this have been described including medial acetabular bone grafting with cemented cups, protrusio rings or porous coated cementless cups fixed with multiple screws. The latter technique has been shown to be more durable and associated with better outcomes. THA in protrusio acetabuli starts with templating of the preoperative x-rays to determine the optimal acetabular implant size and final position of the acetabular component that restores the hip COR to the normal position. Patients with protrusio acetabuli often have varus oriented femoral necks and the femur needs to be carefully templated as well to insure that an appropriate femoral component is available that will allow for restoration of the patient's anatomy. Cartilage covering the thinned medial wall needs to be carefully removed without disruption of the medial acetabular wall. The acetabulum is then carefully reamed with the goal of obtaining stable peripheral rim support of a cementless socket and at least 50% contact of the implant on good quality host bone. Unlike acetabular preparation in the normal hip, preventing the reamer from “bottoming out” is essential in order to obtain desired rim support and return of the hip COR to the normal lateralised position. When good rim support of the reamer is obtained, a trial component is placed and intraoperative x-ray obtained to confirm fit, position and restoration of hip COR. Limited addition reaming can be performed to obtain desired degree of press fit (1‐2mm) and contact with host bone. Morselised autograft from the femoral head and neck is then packed into the medial defect and reverse reamed. The cementless acetabular component is then impacted into position and fixed with screws. Weight bearing is determined by bone quality, size and containment of the medial defect, amount of contact of the cementless cup with host bone and stability of the acetabular construct. Incorporation of autograft bone in the acetabulum and stable long term fixation occurs reliably if stable initial press-fit fixation of the cementless cup is obtained. Restoration of hip COR to within 7mm of its normal location is associated with better implant survival