Intro: Anatomical abnormality associated with severe developmental dysplasia of the hip presents technical difficulties at THR. Patients often present at a younger age and may have had previous surgery. We report the difficulties encountered during surgery, and the long term results of patients who had Crowe 3 or 4 DDH and a technically difficult primary hip arthroplasty using the modular S-ROM stem. Method: 28 patients were entered into the prospective trial. The average age of the patient at surgery was 45 (range 23–74 years). All patients underwent surgery by the senior author using the S-ROM femoral stem. They were followed up for an average of 10 years (range 5–16 years), clinical scores recorded by a clinician other than the surgeon and radiographs were examined by an independent radiologist. Results: 21 patients required a significant autologous bone graft, one patient had a large allograft and six patients required femoral shortening at the time of their THR. 4 patients had a technical complication during surgery. The average pre-op Harris Hip Score was 37, at 5 years it was 83, and at 10 years 81. The SF12 measure of physical and mental wellbeing was 43.90 physical/54.48 mental at 5 years, and 41.64 physical/54.03 mental at 10 years. The WOMAC average score (the lower the score the better the outcome) was 27 at 5 years and 23 at 10 years. None of the S-ROM stems had been revised, 2 hips had undergone acetabular revision and one hip had a liner exchange. None of the S-ROM stems were loose at latest follow-up. Four hips had osteolysis in Gruen zone 1, one hip had osteolysis in zone 7, and one hip had osteolysis in zone 1 and 7. There was no evidence of osteolysis around or distal to the sleeve. Conclusion: The S-ROM stem used in primary THR shows excellent results at 10 years in patients with anatomical abnormality related to severe DDH. S-ROM stem/sleeve modularity allows femoral component anteversion independent of the position of best fit in the proximal femur, and helps overcome the technical difficulty in these patients

Aims. Accurate positioning of the acetabular component is essential for achieving the best outcome in total hip arthroplasty (THA). However, the acetabular shape and anatomy in severe hip dysplasia (Crowe type IV hips) is different from that of arthritic hips. Positioning the acetabular component in the acetabulum of Crowe IV hips may be surgically challenging, and the usual surgical landmarks may be absent or difficult to identify. We analyzed the acetabular morphology of Crowe type IV hips using CT data to identify a landmark for the ideal placement of the centre of the acetabular component as assessed by morphometric geometrical analysis and its reliability. Patients and Methods. A total of 52 Crowe IV and 50 normal hips undergoing total hip arthroplasty were retrospectively identified. In this CT-based simulation study, the acetabular component was positioned at the true acetabulum with a radiographic inclination of 40° and anteversion of 20° (Figure 1). Acetabular shape and the position of the centre of the acetabular component were analyzed by morphometric geometrical analysis using the generalized Procrustes analysis (Figure 2). To describe major trends in shape variations within the sample, we performed a principal component analysis of partial warp variables (Figure 3). Results. The plot of the landmarks showed that the centre of the acetabular component of normal hips was positioned around the centre of the acetabulum and superior and slightly posterior on the acetabular fossa (Figure 3). The acetabular shapes of Crowe IV hips were distinctively triangular; the ideal position of the centre of the acetabular component was superior on the posterior bony wall (Figure 3). The first and second relative warps explained 34.2% and 18.4% of the variance, respectively, compared with that of 28.6% and 18.0% in normal hips. We defined the landmark as one-third the distance from top on the posterior bony wall in Crowe IV hips. The average distance from the centre of the acetabular component was 5.6 mm. There were 24 hips (50%) for which the distance from 1/3 pbw was within 5 mm, and 43 hips (89.6%) for which the distance was within 10 mm. Conclusions. Morphometric geometrical analysis showed that the acetabulum shape of Crowe type IV hips was distinctively triangular; the centre of the acetabular component was not positioned at the centre of the acetabulum, but rather superior on the posterior bony wall. The point one-third from the top on the posterior bony wall was a useful landmark for surgeons to set the acetabular component in the precise position in Crowe IV hips. This avoids the risk of using a smaller acetabular component and destruction of the anterior wall. For any figures or tables, please contact the authors directly

Intro. Sciatic nerve injury (SNI) is a rare and potentially devastating complication after total hip arthroplasty (THA). Neural monitoring has been found in several studies to be useful in preventing SNI, but can be difficult to practically implement during surgery. In this study, we examine the results of using a handheld nerve stimulator for intraoperative sciatic nerve monitoring during complex THA requiring limb lengthening and/or significant manipulation of the sciatic nerve. Methods. We retrospectively reviewed a consecutive series of 11 cases (9 patients, 11 hips) with either severe developmental dysplasia of the hip (Crowe 3–4) or other underlying conditions requiring complex hip reconstruction involving significant leg lengthening and/or nerve manipulation. Sciatic nerve function was monitored intra-operatively with a handheld nerve stimulator by obtaining pre- and post-reduction conduction thresholds during component trialling. The results of nerve stimulation were then used to influence intraoperative decision- making (downsizing components, shortening osteotomy). Results. No permanent postoperative sciatic nerve complication occurred, with an average increase of 28.5mm in limb length, ranging from 6 to 51mm. In 2 out of 11 cases, a change in nerve response was identified after trial reduction, which resulted in an alternate surgical plan (femoral shortening osteotomy and downsizing femoral head). In the remainder cases, the stimulator demonstrated a response consistent with the baseline assessment, assuring that the appropriate lengthening was achieved without SNI. One patient had a transient motor and sensory peroneal nerve palsy, which resolved within two weeks. Conclusions. The intraoperative use of a handheld nerve stimulator facilitates surgical decision-making and can potentially prevent SNI. The real-time assessment of nerve function allows immediate corrective action to be taken before nerve injury occurs

Introduction. The aim of this study was to compare patient reported outcomes, radiographic measurements, and survival free from total hip arthroplasty (THA) in patients who underwent periacetabular osteotomy (PAO) for mild, moderate, or severe developmental dysplasia of the hip (DDH). Methods. We performed a retrospective cohort study on all patients (n=223, n=274 hips) who underwent a PAO procedure between May 1996 and May 2016, by a single surgeon at one academic center. Cases with a history of retroversion (n=64), Perthes (n=5), and those with <2 years of follow-up (n=63) were excluded. Patients were evaluated based on severity of dysplasia using the preoperative lateral center edge angle (LCEA): 18° – 25° was considered mild dysplasia (n=19), 10° – 17° moderate (n=62), and <10° severe (n=61). There was no difference in patient characteristics (age, sex, body mass index, or ASA score) between then cohorts (all, p>0.05). NIH PROMIS outcome measures included the physical function computerized adaptive test (PF CAT) and the Global 10 health assessment. Generalized estimating equations were used for all comparisons and missing data was imputed using the multivariate imputation by chained equations method. A Kaplan-Meier analysis was used to assess survival. Failure was defined as conversion to THA and follow-up was ended at time of failure or at the time of last follow-up. Mean follow-up was five years (1 – 19). Results. Using the mild group as a reference, there was no difference in the PF CAT T-scores for moderate (p=0.167) or severe (p=0.910) dysplasia. These findings were similar for the Global physical and Mental Health T-scores (all, p>0.05). These outcomes were all within ½ of the standard deviation of the US general population (T-Score 50, SD 10) and demonstrate an average level of function or health. There was no difference in the numeric pain scores at last follow-up (all, p>0.05), with scores of approximately 2 – 3 units. There was no difference (all, p>0.05) in the proportion of patients achieving the correction goal for the LCEA (20° – 40°) where 95% (95% CI, 85% – 105%) of the mild group, 95% (95% CI, 90% – 100%) of the moderate group, and 76% (95% CI, 65% – 87%) in the severe group achieved this goal. The average amount of correction was roughly 12° (9° – 15°) in the mild, 15° (13° – 16°) in the moderate (p=0.185), and 23° (21° – 25°) in the severe group (p<0.001). The post-operative anterior center edge angle was in goal in approximately 70% – 80% of the cases for all groups (all, p>0.05). The post-operative acetabular index was within goal in roughly 65% – 75% of the cases in each group (all, p>0.05). Survival free from THA at five years was 100% for the mildly dysplastic, 92% (77% – 98%) for moderately dysplastic, and 96% (85% – 99%) for severely dysplastic hips (p=0.696). Conclusion. Although requiring less correction than hips with moderate or severe dysplasia, we found PAO for mild dysplasia to be associated with promising patient reported outcomes, consistent with that of the general US population, and excellent survivorship at 5 years. Future studies should compare these results to hip arthroscopy in the setting of mild hip dysplasia

Introduction. The purpose of this study was to demonstrate postoperative improvement and high satisfaction rates after a surgical approach that includes arthroscopic labral repair only, in patients with borderline dysplasia, without instability. Methods. Between September 2009 and December 2011, patients less than 50 years old who underwent hip arthroscopy for symptomatic intra-articular hip disorders, with a lateral center-edge (CE) angle between 20 and 25, were included in this study. Patients with Tönnis grade 2 or greater, hip joint space narrowing, severe hip dysplasia (CE〈20), hip joint instability and Legg-Calve-Perthes disease were excluded. Patient-reported outcome scores, including the modified Harris Hip Score (mHHS), Western Ontario and McMaster Universities Arthritis index (WOMAC), and visual analog scale (VAS) for pain were obtained in all patients preoperatively and at 1, 2, and 3 years postoperatively. Results. A total of 36 patients met the criteria to be included in the study. Of these, 32 (88.8%) patients were available for follow-up. There was a significant improvement in mHHS from 67.19±7.66 to 82.69±6.95 (P<0.001), and WOMAC score from 58.90±5.77 to 77.90±6.38 (P<0.001). There was a significant improvement in VAS scores from 5.8 to 2.9 (P<0.001). There was a significant improvement in range of motion, flexion from 108.44±7.77 to 115.31±6.08 (P<0.001) and external rotation from 29.06±5.74 to 33.13±4.88 (P<0.001). Conclusions. The current study demonstrates favorable results in borderline dysplasia hip without instability at minimum 3-year follow-up for an arthroscopic approach that includes labral repair. Labrum is the main key-stone structure, which should be preserved in borderline dysplasia hip for functional and pain improvement. Also the prognosis of treatment is probably forecasted more by the nature of stability and the intra-articular pathology rather than simply the presence or absence of radiographic finding of borderline dysplasia

Purpose. The purpose of this study was to demonstrate postoperative improvement and high satisfaction rates after a surgical approach that includes arthroscopic labral repair only, in patients with borderline dysplasia, without instability. Methods. Between September 2009 and December 2011, patients less than 50 years old who underwent hip arthroscopy for symptomatic intra-articular hip disorders, with a lateral center-edge (CE) angle between 20 and 25, were included in this study. Patients with Tönnis grade 2 or greater, hip joint space narrowing, severe hip dysplasia, hip joint instability and Legg-Calve-Perthes disease were excluded. Patient-reported outcome scores, including the modified Harris Hip Score (mHHS), Western Ontario and McMaster Universities Arthritis index (WOMAC), and visual analog scale (VAS) for pain were obtained in all patients preoperatively and at 1, 2, and 3 years postoperatively. Results. A total of 36 patients met the criteria to be included in the study. Of these, 32 (88.8%) patients were available for follow-up. There was a significant improvement in mHHS from 67.19 ± 7.66 to 82.69 ± 6.95 (P<0.05), WOMAC score from 58.90 ± 5.77 to 77.90 ± 6.38 (P<0.05), and VAS scores from 5.8 ± 0.88 to 2.9 ± 0.62 (P<0.05). There was a also improvement in range of motion, flexion from 108.44 ± 7.77 to 115.31 ± 6.08 (P<0.05) and external rotation from 29.06 ± 5.74 to 33.13 ± 4.88 (P<0.05). Conclusions. The current study demonstrates favorable results in borderline dysplasia hip without instability at minimum 3-year follow-up for an arthroscopic approach that includes labral repair. Labrum is the main key-stone structure, which should be preserved in borderline dysplasia hip for functional and pain improvement

Aims

The aim of this study was to evaluate the reliability and validity of a patient-specific algorithm which we developed for predicting changes in sagittal pelvic tilt after total hip arthroplasty (THA).

Introduction. The anatomic abnormalities associated with the dysplastic hip increase the complexity of hip arthroplasty, in addition previous femural osteotomy can deformate proximal femur. Despite the fact that uncemented cup and stems are specifically designed for dysplasia to recover the true acetabular region in Crowe IV and sometimes Crowe III additional surgical procedure are required. Purpose of the study is to verify surgical procedures and explore reconstruction options on severe hip dysplasia. Materials and methods. In last 25 years, 2308 arthroplasties were performed in dysplastic hips (565 cases had a previous femoral osteotomy). In 128 cases was required a correction of femoral side deformity: in 64 cases was performed a greater trochanter osteotomy (in 12 of these a proximal femoral shortening was associated), 55 cases were treated by a shortening subtrochanteric osteotomy (that allows corrections in any plane) and in 9 cases was performed a distal femur osteotomy. Discussion. Long-term results in these patients are steadily inferior to those obtained in general population (70% survival rate at 15 years). On femoral side early failures reflect learning curve and are due to insufficient fixation of osteotomies. Despite this, the more promising outcomes are concerning shortening sub-trochanteric osteotomy with uncemented stem but only early and mid-term data are available

Introduction. We present our experience of the coned hemi-pelvis (‘ice-cream’ cone) implant, using an extended posterior approach to the hip joint, in the management of pelvic bone loss and pelvic discontinuity. Methods. Retrospective study conducted utilising a prospectively collected database. Patients who underwent an ice-cream cone reconstruction between August 2004 – September 2011 were identified. All had a posterior approach to the hip. Femur prepared in the standard fashion. A variety of femoral components used. Demographic data was recorded along with the indication for surgery and outcomes. Results. 16 patients identified. Mean age was 62.2 years. 5 (31.25%) male. 11 (69.75%) female. Indications included; multiple hip revision surgery 4(25%); post Gridlestones for severe hip dysplasia 1 (6.25%); peri-acetabular metastatic deposits 11 (68.75%) from breast, renal, endometrial, prostatic, myeloma primary malignancies. Mean follow-up was 32.06 months. Complications; 1 intra-operative death from tumour embolus; 1 dislocation; 1 superficial surgical site infection. 3 deaths from their primary malignancy. Mean time from prosthesis implantation to death was 14.5 months. All patients at last follow-up were mobilizing. No implant has needed to be revised. Discussion. Pelvic bone loss provides reconstructive challenges. The coned hemi-pelvis is simple to make, easy and versatile to use even when there is little pelvis remaining. It provides a method of negotiating hip reconstruction in patients with severe pelvic bone loss. Orthopaedic surgeons are familiar with the posterior approach to the hip. The ice-cream cone implant can therefore be placed with ease using this well-known approach to the hip

Introduction: The anatomic abnormalities associated with the dysplastic hip increase the complexity of hip arthroplasty, in addition previous femural osteotomy can deformate proximal femur. Despite the fact that uncemented cup and stems are specifically designed for dysplasia to recover the true acetabular region in Crowe IV and sometimes Crowe III additional surgical procedure are required. Purpose of the study is to analize surgical procedure and then reconstruction options on severe hip dysplasia. Materials and methods: From 1984 till today 2308 cases of arthroplasty were performed in dysplastic hip, 565 cases have a previous femoral osteotomy; out of these 2308 cases 128 cases need treatment for corrections of femural side deformity. 64 cases were subjected to a greater trochanteric osteotomy. In 12 cases proximal femural shortening was associated. In 9 cases rotational abnormality and shortening were controlled with a distal femur osteotomy. 55 cases were treated by a shortening subtrochanteric osteotomy that allows corrections of any deformity. Only uncemented stems were used and in the majority of cases a specific device for displastic hip (Wagner Conus produced by Zimmer). Discussion: Long-term results in these patients are steadily inferior to that in the general population (70% survival at 15 yrs). On femural side early failures are the reflection of learning curve and are due to insufficient fixation of the osteotomy. Despite this, the more promising outcomes are concerning shortening subtrochanteric osteotomy with uncemented stem but only early and mid-term data are available

Introduction and Objectives: We compared the clinical and radiological results in patients under and over 40 years of age who had received a non-cemented alumina-alumina hip replacement. Materials and Methods: We studied 337 Cerafit acetabular cups implanted in 4 hospitals in association with Multicone-Hydroxyapatite stems with alumina-alumina bearing surfaces. Group 1 consisted of 63 patients under 40 years of age and group 2 of 274 patients over 40 years of age. Mean follow-up was 59.0 months. Demographic data and clinical and radiological results of both groups were compared. Results: There were no cases of primary arthritis in group 1, however severe hip dysplasia and juvenile rheumatoid arthritis were frequent (p< 0.001). Weight (p< 0.001) and degree of activity (p=0.003) were greater in group 2. Preoperative function (p=0.03) and mobility (p< 0.001) were worse in group 1. There were 3 cup revisions in group 1 and 4 (including an alumina breakage) in group 2. Survival with no revision due to any cause was 91.4+5.1% in group 1 and 97.0+ 1.1 in group 2 (p=0.4007). There were no noises. Clinical and radiological results were similar in both groups. Discussion and Conclusions: Diagnoses were different in both groups, the younger patients were in worse conditions. In spite of these differences, the alumina-alumina prosthesis showed similar results in both groups in the medium term. Long-term follow-ups are necessary to confirm these results

Rotational acetabular osteotomy (RAO) is a circumacetabular osteotomy of the acetabulum designed to correct the dysplastic hip. In this procedure, the femoral head is covered with the articular cartilage of the acetabulum and the forces of weight-bearing are distributed more evenly. The purpose of this study was to determine whether RAO is effective in delaying the onset of arthrosis in patients with painful hip dysplasia. We determined the outcome of 20 female patients in whom RAO was performed between 1975 and 1984; all were aged 20 to 29 years at the time of surgery. The pre-operative centre-edge angle of Wiberg was 0 or negative with proximal subluxation of the femoral head. Of these, 10 were lost to follow-up before the age of 42. In these patients, however, radiographs showed no signs of arthrosis at the last follow-up. The remaining 10 patients were examined 15 to 25 years after surgery, when they were 42 to 47 years old. Radiographs revealed findings of arthrosis in only two of them who had had the secondary acetabulum before surgery. To evaluate the efficacy of preventive medicine, it is necessary to compare the results of intervention with the natural course of the disease. Wiberg reported on the natural history of seven female patients with severe hip dysplasia in 1939. When these patients were 13 to 34 years old, radiographs demonstrated no sign of arthrosis and the centre-edge angle was equal to or less than 12 degrees with proximal subluxation of the femoral head. These hips deteriorated to advanced arthrosis by the age of 42 years. Thus the outcome of our patients was significantly better than the natural course. In conclusion, our study suggests that RAO is effective in delaying the onset of arthrosis in patients with painful hip dysplasia

In severe hip dysplasia the fixation of the cup becomes a technical hazard, and the augmentation of the acetabulum with an autologous bone graft is helpful when the bone stock is deficient. Twenty-four patients (25 hips) were operated on between 1993 and 1994; the mean age at operation was 49 years (range, 28 to 71 years). The mean Sharp acetabular angle was 55degrees (range, 45 to 63degrees). The dislocation of the femoral head was graded Crowe 1 in 4 hips, grade II in 5 hips, Grade III in 10 hips, and grade IV in 6 hips. Autologus bone was harvested from the femoral head and from the proximal metaphysis of the femur. The fixation of the graft to the anterior wall and to the roof of the acetabulum was achieved using impaction using the reinforcement ring with hook of Ganz. A separate cohort of 25 patients (25 hips) operated on between 1998 and 1999 was investigated using radiostereometry (RSA). The clinical outcome of the hips was prospectively reviewed using the Harris hip score at an average of 8.3 years (range 8 to 9 years) postoperatively. Twenty-four hips were pain-free, and had a range of motion of 210 degrees or more except 3. A positive Trendelenburg sign disappeared in 88% of the hips. One cup (4%) showed radiological loosening with migration and required revision surgery. No signs of migration or progressive radiolucent lines were present in the remaining hips. The graft appeared united without resorption in 24 hips. The results of micromotion analysis using RSA confirm the stable fixation of the reinforcement ring in dysplasia. Satisfactory middle term results of total hip replacement for severe dysplasia can be achieved using appropriate surgery and specific components. The use of reinforcement ring is important to obtain adequate primary stability, and to protect the graft during healing

Purpose of the study: Labrum lesions can be an important source of hip pain. Besides the classical causes, certain morophological anomalies can be associated with labrum lesions. The purpose of this work was to study the contribution of plain x-rays to the search for morphological anomalies of the hip in patients with labrum lesions. Materials and methods: Twenty-six patients with labrum lesions were included in this study. The plain x-rays protocol included an anteroposterior view of the pelvis in the standing position, a Lequesne oblique view and a lateral view of the neck in the hip flexion position. Patients with severe hip dysplasia (VCA or VCI < 15° or THE > 15°) were excluded. Measurements were made after digitalization using a dedicated software. Measures were: neck-shaft angle, acetabular cover, lateral alpha (neck axis, center of the head, most lateral point of the head sphere), lateral offset, acetabular version. Femoral data in flexion were compared with 20 controls. Results: Acetabular cover was considered moderately insufficient in five patients (VCA and/or VCE 15–25°). These patients had the same alpha angle as the control population (56°), i.e. no anomaly of the neck-head junction. The 21 patients with non-dysplastic hips exhibited a significantly greater alpha angle (64±9° versus 54.6±8°, p< 0.01) than the controls. All controls presented an alpha angle ≤ 69°. Among the 21 non-dysplastic patients, five presented coxa vara (< 125°), five acetabular retroversion, nine an alpha angle > 69°. In all, 77% of patients presented morphological anomalies of the hip. Among the six «normal» hips using these measures, three presented a pistol-grip aspect which could not be quantified with these measures. Discussion: This analysis confirms the association between morphological anomalies detectable on plain x-rays and labrum lesions in patients who do no present severely insufficient acetabular coverage. We were unable to detect any difference in femoral offset compared with the control population. Conclusion: A standard x-ray protocol can, in the majority of cases, detect morphological anomalies of the hip, an important etiological diagnostic element for understanding pathogenic mechanisms

Objectives/Background: Long-term outcome in THR is multifactorial influenced. Malpositioning leads to complications as early loosening, leg length difference or dislocation of the artificial joint. A proven factor for early losening is a misplacment of the center of rotation or varusposition of the stem. A higher luxation risk results out of high inclination and anteversion angles an reduced soft tissue tension. Aim of this study was to prove the image free navigation software in the modular Navitrack-System to check the implant position based on anatomical intraoperative acquired data. Design/Methods: In 35 consecutive cases we implantet the ACA screwcup and the Optan anatomical stem with use of the Navitrack navigation System. The software calculates al relevant data out of intraopertive probed landmarks. Intraoperative the shifting of the center of rotation, the cup anteversion and inclination, the stem inclination and torsion and the leglength shift is shown in real time. Intraoperative data were compared with postoperative position measurement in plain X-rays and in 15 patients in postoperative CT scans. Results: In all cases navigated implantpositioning was possible. In 3 cases stem positioning was not possible cause of refference loosening. Mean inclination of the cup as shown in the Navigation System was 52 (range 45 – 58 ), mean anteversion was 11 (range -5 – 27). Mean postoperative inclination measured on postoperative X-Ray was 53,8 (range 49 – 60). The difference between the shown values from the CAS System to the postoperative X Ray for the inclination was 1,8 (range -9 – 6). The leg length difference on postoperative X-ray was in mean 3,1 mm, on screenshots 2,8 mm. The difference between screenshot and X ray was in mean 0,83 mm. Conclusions: This study shows, that with the CT free software for the Navitrack-System reliable cup and stem navigation is possible. Whenever the hip joint allows to probe a spherical segment in the femoral head or acetabulum navigated THR is possible without the need of intraoperative fluoroscopy or preoperative CT scan. For leg length control and cup Inclination the data are still promising. Further investigation is necessary for stem axis and cup anteversion according to the navigation based reference coordinate system. Whenever no geometric sphere existent, e.g. severe hip dysplasia, the system must be developed as a hybrid system with CT (NMR) based cup and image-less stem navigation

Metal-on-metal hip resurfacing (MOMHR) is a good surgical indication for young active patients. However, it cannot be used in patients with severe CDH and in particular a too short head/neck. To address these cases, a new surgical technique consisting of augmentation of the femoral head with impacted morcellized bone grafts has been developed. 32 osteoarthritis patients following severe congenital insufficiency of the femoral head/neck were treated with MOMHR combined with femoral head augmentation. The required amount of augmentation was calculated on preoperative X-rays and confirmed during surgery. Using special instrumentation, bone chips produced while reaming the socket and trimming the head were impacted on the head to achieve the desired reconstruction and lengthening. Finally, the femoral component was cemented. Mean patient age was 49+ 9 years (18–66). Median head lengthening was 12+ 2 mm. Mean follow up is 4.2 years (3–6). Mean preoperative Harris hip score (HHS) was 58 and at follow-up 95 (p < 0.05). Mean leg lengthening was 2.2 cm (p = 0.001). In all Gruen zones, bone mineral density (BMD) decreased during the first 3 months. At 2 years in zone 1 mean BMD increased to 96.8% (p = 0.009) and in zone 7 to 102.1% (p = 0.05). A correlation was found between valgus positioning of the femoral components and increased BMD (p = 0.005). This impaction bone grafting technique expands the use of MOMHR to patients with severe congenital hip dysplasia leading to a more anatomical reconstruction with a full recovery of function and BMD

Objective

Hip arthroscopy in the setting of hip dysplasia is controversial in the orthopaedic community, as the outcome literature has been variable and inconclusive. We hypothesise that outcomes of hip arthroscopy may be diminished in the setting of hip dysplasia, but outcomes may be acceptable in milder or borderline cases of hip dysplasia.