In order to evaluate the relationship between acetabular and proximal femoral alignment in the initiation and evolution of osteoarthritis of the dysplastic hip, the acetabular and femoral angles were calculated geometrically from radiographs of 62 patients with pre-arthrosis and early osteoarthritis. The sum of the lateral opening angle of the acetabulum and the neck-shaft angle was defined as the lateral instability index (LII), and the sum of the anterior opening angle of the acetabulum and the anteversion angle of the femoral neck as the anterior instability index (AII). These two indices were compared in dysplastic and unaffected hips. A total of 22 unilateral hips with pre-arthrosis were followed for at least 15 years to determine whether the two indices were associated with the progression of osteoarthritis. The LII of the affected hips (197.4 (. sd. 6.0)) was significantly greater than that of the unaffected hips (1830 (. sd. 6.9)). A follow-up study of 22 hips with pre-arthrosis showed that only the LII was associated with progression of the disease, and an LII of 196 was the threshold value for this progression

Abstract. OBJECTIVES. Although surgical periacetabular osteotomy (PAO) for hip dysplasia aims to optimise acetabular coverage and restore hip function, it is unclear how surgery affects capsular mechanics and joint stability. The purpose was to examine how the reoriented acetabular coverage affects capsular mechanics and joint stability in dysplastic hips. METHODS. Twelve cadaveric dysplastic hips (n = 12) were denuded to the capsule and mounted onto a robotic tester. The robot positioned each hip in multiple flexion angles (Extension, Neutral 0°, Flexion 30°, Flexion 60°, Flexion 90°) and performed internal-external rotations and abduction-adduction to 5 Nm in each rotational or planar direction. Each hip underwent a PAO, preserving the capsule, and was retested postoperatively in the robot. Paired sample t-tests compared the range of motion before and after PAO surgery (CI = 95%). RESULTS. Pre-operatively, the dysplastic hips demonstrated large ranges of internal-external rotations and abduction-adduction motions throughout all flexion positions. Post-operatively, the PAO slackenend the anterosuperior capsule and tightened the inferior capsule. This increased external rotation in Flexion 60° and Flexion 90° (∆. ER. = +16 and +23%) but provided lateral coverage to decrease internal rotation at Flexion 90° (∆. IR. = –15%). The PAO also reduced abduction throughout, but increased adduction in Neutral 0°, Flexion 30°, and Flexion 60° (∆. ADD. = +34, +30%, +29% respectively). CONCLUSIONS. The PAO provided crucial osseous structural coverage to the femoral head, decreasing hypermobility and adverse loading at extreme hip flexion-extension. However, it also slackened the anterosuperior capsule and increased adduction and external rotation, which may lead to ischiofemoral impingement and adductor irritations. Capsular instability may be secondary to acetabular undercoverage, thus capsular alteration may be warranted for larger corrections or rotational osteotomies. To preserve native hip and delay joint degeneration, it is crucial to preserve capsule and elucidate amount of reorientation needed without causing iatrogenic instability. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Introduction. Bernese periacetabular osteotomy (PAO) repositions the acetabulum to increase femoral head coverage (FHC) in hip dysplasia. Currently, there is a paucity of objective peri-operative metrics to plan for optimal acetabular fragment repositioning. The MSk Lab Hip 3D Planner (MSkL-HP) measures acetabular morphology and simulates PAO cuts to achieve optimal FHC. We evaluated how adjusting location and orientation of cutting planes can alter FHC. Method. MSkL-HP simulated 274 feasible PAOs on four dysplastic hips. Femoroacetabular anatomy was landmarked to simulate cutting planes. Posterior column and ischial cuts were standardised, whilst iliac and pubic cut combinations varied. The slope of the iliac cut was either neutral (aligned to pelvis), exit point 5mm above the entry point (+5), or 5mm below (-5). The slope of the pubic cut was either 90°, 50°, or 70° (medial-to-lateral). Iliac and pubic cuts were simulated 0, 5 and 15mm - distal and medial – to a classic cut. Outcome measures were achieved LCEA, Tönnis, FHC and % bone overlap at the pubic cut. Targets were LCEA >30°, Tönnis angle <10°, and FHC >70% and minimum bone overlap ≥10%. Results. All feasible PAOs resulted in improvement from pre-operative metrics. Personalised cutting planes provided greater benefit than standard planes. Kruskal Wallis tests showed that the iliac cut at 5mm or 15mm resulted in a greater LCEA and lower Tönnis compared to the classic cut (p<0.05). Changing location of the pubic cut, and slope of the iliac and pubic cuts did not significantly affect LCEA and Tönnis in all hips (p<0.05). Cut combinations optimising metrics were associated with a lower % pubic cut overlap. Conclusion. MSkL-HP feasibly and reliably planned personalised PAO, measuring pre-operative and simulated post-operative objective metrics. Patient-specific pubic and iliac cuts enable greater correction whilst maintaining bone overlap. Further simulations on patients with varying morphology may improve standard techniques

When performing total hip replacements in patients with hip dysplasia, acetabular augmentation may be required to prevent early component failure. Preoperative radiographic templating may help estimate acetabularcomponent coverage but has not previously been shown to predict the need for augmentation. We developed a simple method to estimate the percentage of acetabular component coverage from pre-operative radiographs (True: False cup ratio). We aimed to evaluate whether this couldpredict the need foracetabular augmentation at primary total hip replacement for patients with dysplastic hips. We reviewed all patients with hip dysplasia who underwent a primary total hip replacement from 2005–2012. Classification of hip dysplasia (Crowe), centre edge angle (CEA), Sharp and Tonnis angles were determined on pre-operative radiographs for each patient. Templating was performed on anteroposteriorand lateral view hip radiographs to determine the likely percentage of acetabular component coverage using the True: False cup ratio. Patients requiring acetabular augmentation at time of primary total hip arthroplasty were noted. 128 cases were reviewed, 31 (24%) required acetabularaugmentation. Comparison between augmented and non-augmented cases revealed no difference in the mean CEA (p = 0.19), Sharp angles (p = 0.76) or Tonnis angles (p = 0.32). A lower True Cup: False Cup ratio was observed in the augmented groupcompared to the non-augmented group(median = 0.68 vs 0.88, p < 0.01). Preoperative templating can help predict which dysplastic hips are likely to require acetabular augmentation at primary total hip replacement

The outcome of periacetabular osteotomy in dysplastic hips is dependent on the absence of preoperative osteoarthritis [OA]. The purpose of this study was to analyze whether Tonnis grading is a reliable predictor of OA in patients with hip dysplasia. Thirty patients were identified who had undergone hip arthroscopy surgery to assess their suitability for periacetabular osteotomy. Radiographs were assessed for anterior centre edge angle, lateral centre edge angle, Tonnis angle and Tonnis grade for OA changes. The radiographic grading of OA was compared with arthroscopic findings. Results. The average age at the time of arthroscopy was 34.97 [16 – 53yrs] (28 females). Tonnis grade did not correlate with arthroscopic findings (p=0.082). There was a trend for patients with a higher Tonnis grade to have more OA changes. Of the 30 patients, all 3 with grade 0 were fit for periacetabular osteotomy, while only 8 out of 24 with grade I, and 1 out of 3 with grade II were fit for periacetabular osteotomy. This study reports that even when radiographic grading showed minimal OA changes, arthroscopy findings indicated significant OA changes. Hence radiographic grading is a poor indicator of OA and other diagnostic modality should be sought before proceeding with joint preserving surgery in this highly selected subgroup of dysplastic hips

Background. Although the tribological characteristics are excellent, cup fixation has been one of the limitations in alumina-on-alumina total hip replacement (THR), so different types of materials and surfaces have been developing. We analysed the clinical and radiological outcome of two different uncemented cups for the same alumina-on-alumina THR. Methods. 679 hips were prospectively followed for at least 5 years. 342 had a hydroxyapatite (HA)-coated relatively smoothed tri-radius cup, implanted between 1999 and 2005 (group 1), and, 337 had a HA-coated macotextured tri-radius implanted between 2006 and 2009 (group 2). Dysplastic hips were more frequently observed in group 2. We compared screw use in both groups as primary fixation, the clinical results, and the radiological appearance of cup loosening. Results. Multivariate analysis showed that group 1, osteopenic and dysplastic acetabulae and women had a higher risk of screw use (p=0.004, HR: 1.68,95% CI: 1.18 to 2.41; p<0.001, HR: 2.25 95%, CI: 1.55 to 3.38; p<0.001, HR: 4.95, 95% CI: 2.83 to 8.64; p=0.011, HR: 1.58, 95% CI: 1.11 to 2.25, respectively). Although the pre-operative clinical score was worse in group 2, the post-operative results were better (p<0.001). There were no complications related to alumina. 15 cups were revised for loosening in the group 1 and 2 in the group 2. The cumulative probability of not having a revision for cup loosening at 15 years for the whole series was 93.3 % (95% CI: 89.6 to 96.9). The probability of not having cup loosening was 93.3% (95% CI: 89.7 to 96.9) in group 1 and 97.5% (95% CI: 93.5 to 100) in group 2. Conclusions. Despite worse pre-operative conditions, the macrotextured surface of the cup in the second group improved bone fixation in this series. Continued follow-up will be required to determine if reduction in wear between the alumina-on alumina bearings results in less osteolysis and loosening

The pathology of the posterior acetabular legion in femoroacetabular impingement (FAI) syndrome, so called “contre-coup region”, is still unclear. . 18. F-fluoride positron emission tomography (PET) is a functional imaging modality, which reflects the osteoblast activity. Recent technological advances in PET combined with computed tomography (CT) imaging allowed us to obtain detailed 3-dimensional (3D) morphological information. We evaluated the abnormal uptake of . 18. F-fluoride PET/CT on posterior acetabular lesion in FAI syndrome cases. We enrolled forty-one hips from 41 patients who were diagnosed as FAI syndrome and were performed . 18. F-fluoride PET/CT between October 2014 and October 2016. In each hip, the maximum standardized uptake value (SUV. max. ) on the posterior acetabular was measured. The cases were divided into 4 groups; cam-type (11 cases), pincer-type (7), combined-type (11), dysplastic developmental hip (DDH) with cam morphology (12). The average SUV. max. of the pincer-type was significantly smaller than that of the other 3 groups (p < .05). The percentage of the cases with SUV. max. ≥ 6 was 81.8% in cam-type, 28.6% in pincer-type, 90.9% in combined-type, 91.7% in DDH with cam morphology. Furthermore, the average degree of α angle of the cases of SUV. max. ≥ 6 was significantly higher than that of the cases of SUV. max. < 6 (p = .005). Although actual biomechanical mechanism in contre-coup region is still controversial, this result indicated that the cam morphology related to the posterior acetabular lesion with accelerated bone metabolism

We studied the morphometry of 35 femora from 31 female patients with developmental dysplasia of the hip (DDH) and another 15 from 15 age- and sex-matched control patients using CT and three-dimensional computer reconstruction models. According to the classification of Crowe et al 15 of the dysplastic hips were graded as class I (less than 50% subluxation), ten as class II/III (50% to 100% subluxation) and ten as class IV (more than 100% subluxation). The femora with DDH had 10 to 14° more anteversion than the control group independent of the degree of subluxation of the hip. In even the most mildly dysplastic joints, the femur had a smaller and more anteverted canal than the normal control. With increased subluxation, additional abnormalities were observed in the size and position of the femoral head. Femora from dislocated joints had a short, anteverted neck associated with a smaller, narrower, and straighter canal than femora of classes I and II/III or the normal control group. We suggest that when total hip replacement is performed in the patient with DDH, the femoral prosthesis should be chosen on the basis of the severity of the subluxation and the degree of anteversion of each individual femur

Introduction. Curved varus intertrochanteric osteotomy of the femur is an excellent and minimally invasive method for the treatment of osteonecrosis of the femoral head or osteoarthritis of the hip for joint preservation. However, the early postoperative complications of this procedure may be due to separation at the osteotomy site and an increase in varus angle due to early partial weight bearing. Methods. We modified the curved varus intertrochanteric osteotomy of the femur by performing an additional rotation. Regarding the surgical technique, curved varus osteotomy is performed at an angle of 30 degrees to the femoral shaft and an additional rotational osteotomy is also performed at an angle of 15 or 20 degrees to the osteotomy plane. Partial weight bearing with one-third body weight is permitted 3 weeks after surgery. Results. Curved varus intertrochanteric osteotomy of the femur was designed for developmental dysplastic hip by Nishio in 1969 and reported to have good outcomes in 1971. An important feature of this method is that the incidence of high riding of the greater trochanter or shortening of leg length is less than that in varus intertrochanteric osteotomy. Moreover, good contact at the osteotomy site and less lateral shift of the femoral shaft is observed. However, we have experienced a case of separation at the osteotomy site and increase of the varus angle in our hospital. Previous reports recommended that partial weight bearing with one-third body weight should be initiated after 5 weeks and full weight bearing after 6 months because the contact area is decreased at the osteotomy site by varus osteotomy. The post-operative recovery of the patients with total hip arthroplasty is rapid, therefore, we must consider important issues such as initiating the rehabilitation program early and reducing the duration of hospitalization. As per our experience, we think that partial weight bearing with one-third body weight should be initiated at 3 weeks. At the osteotomy site, we rotated the nearest bone segment to move it such that it intersects the proximal and distal bone cortex. Therefore, the osteotomy site will be stabilized and will have the ability to endure load. Another feature of this technique is that the partial removal of the necrotic area leads to an increase in the healthy load-bearing area. A limitation of this method is that an angle of an additional rotation is up to 30 degrees, because the joint capsule cannot be incised circumferentially and the short external rotator tendons should also be preserved. Conclusion. Modified curved varus intertrochanteric osteotomy is a useful method for the prevention of increased degree of a varus angle as well as for obtaining more intact area of femoral head in osteonecrosis

Objectives

Acetabular component orientation in total hip arthroplasty (THA) influences results. Intra-operatively, the natural arthritic acetabulum is often used as a reference to position the acetabular component. Detailed information regarding its orientation is therefore essential. The aim of this study was to identify the acetabular inclination and anteversion in arthritic hips.

We used a biodegradable mesh to convert an acetabular defect into a contained defect in six patients at total hip replacement. Their mean age was 61 years (46 to 69). The mean follow-up was 32 months (19 to 50). Before clinical use, the strength retention and hydrolytic in vitro degradation properties of the implants were studied in the laboratory over a two-year period. A successful clinical outcome was determined by the radiological findings and the Harris hip score.

All the patients had a satisfactory outcome and no mechanical failures or other complications were observed. No protrusion of any of the impacted grafts was observed beyond the mesh. According to our preliminary laboratory and clinical results the biodegradable mesh is suitable for augmenting uncontained acetabular defects in which the primary stability of the implanted acetabular component is provided by the host bone. In the case of defects of the acetabular floor this new application provides a safe method of preventing graft material from protruding excessively into the pelvis and the mesh seems to tolerate bone-impaction grafting in selected patients with primary and revision total hip replacement.