We compared the long-term clinical and radiological results of hybrid total hip replacement (THR) with metal-on-metal Birmingham hip resurfacing (BHR) in two groups of 54 young patients matched for age, gender, body mass index and pre-operative levels of activity.

The clinical outcome was assessed by the University of California, Los Angeles (UCLA) activity score, the Oxford Hip Score (OHS) and the EuroQol scores. Radiologically, all hips were assessed for migration and osteolysis, the hybrid THRs for polyethylene wear and the BHRs for a pedestal sign.

The mean follow-up of the patients with a hybrid THR was 16 years and for those with a BHR, 15 years. 12 patients with a hybrid THR and 6 with a BHR had died. 2 patients with a BHR refused follow up but remain unrevised and 5 were lost to follow-up, as was 1 with a hybrid THR. The revision rate of the hybrid THRs was 28% (15 of 54) and of the BHRs 11% (6 of 54) (p = 0.029). Radiographs of a further 13 hybrid THRs demonstrated wear and osteolysis but are functioning well and are under observation. Of the unrevised BHRs 96% had radiological changes, of which approximately 17% had progressed over the previous 6 years. All hybrid THRs demonstrated linear polyethylene wear with a mean of 1.84mm (0.06 to 2.6). The BHRs recorded superior OHS (p = 0.03), UCLA (p = 0.0096), and EuroQol visual analogue scores (p = 0.03).

After 15 years, patients with BHRs remained more active and had a lower rate of revision and death than those with hybrid THRs. Both groups demonstrated progressive radiological changes at long-term follow-up.

Cement-induced thermal osteonecrosis is well documented, as is the potential for nerve injury from thermal energy. Cement is often used to augment fixation following excision of humeral metastases. Porcine femurs were used as a model. We sought to find out the maximum temperatures that would be reached in various parts of the bone during the cement setting process, to explore what negative effects this might have on neighbouring bone and nerve.

A 12mm by 12mm window was cut from 12 porcine femoral shafts, and Palacos R+D cement injected into the defect. As cement set, bone surface temperature was measured using infra-red thermal imaging and thermocouples used to measure temperatures at the bone-cement interface, 5mm from the cement bolus, 10mm from cement bolus and an area running around the shaft replicating radial nerve.

Bone surface temperature rose to a maximum of 34.0 C (on average), and 32.9 C in the ‘radial nerve’ thermocouple. Notably, in two bones there were fractures during specimen preparation, and maximum temperatures in these two areas exceeded 41 degrees C.

Average maximum temperatures were 58.1 C, 36.5 C and 30.1 C at the bone cement interface, 5mm and 10mm from the cement bolus respectively.

Cement-in-cement femoral component revision is a useful and commonly practised technique. Onerous and hazardous re-shaping of the original cement mantle is required if the new stem does not seat easily. Furthermore, without removing the entirety of the original cement mantle, the freedom to alter anteversion or leg length is difficult to predict preoperatively. We present data from in vitro experiments testing the compatibility of the top cemented stems according to UK registry figures (NJR 2013). This data augments preoperative planning by indicating which revision stems require minimal or no cement reshaping when being inserted into another stem's mantle. We also present the maximum shortening and anteversion that can be achieved without reshaping the original cement mantle.

In September 2011 our departmental protocol for peri-operative prophylactic antibiotic administration was altered from cefuroxime to gentamicin/flucloxacillin, in response to reported links between cephalosporin use and Clostridium difficile (C. diff) infection.

As both gentamicin and flucloxacillin are known to be nephrotoxic in some patients, we investigated whether the new regimen increases the risk of Acute Kidney Injury (AKI) in patients undergoing elective and trauma hip and knee surgery, classified by severity (AKI Network criteria). The incidence of C. diff was noted.

10 out of 202 (5%) patients receiving cefuroxime (group A) developed AKI, compared with 23 of 210 (11%) patients receiving gentamicin and flucloxacillin (group B) (p=0.012). The severity of the renal injury was higher in the group B patients with 16 sustaining stage II/III AKI, whereas in Group A only one patient sustained a stage II injury and none stage III.

The increased AKI rate in group B was observed equally in hip fracture patients and elective hip/knee replacement patients. However, 3 of 80 (4%) patients with hip fractures who received doses of cefuroxime developed C. diff, with none in the other groups (p=0.04).

The choice of prophylactic antibiotics depends on a careful assessment of benefits and risks. Our data suggests that whereas hip fracture patients may have benefitted from the protocol change with reduced C. diff incidence, elective hip and knee replacement patients sustained additional harm. Different antibiotic regimens may be appropriate for these two groups.

Total Shoulder Resurfacing (TSR) provides a reliable solution for the treatment of glenohumeral arthritis. It confers a number of advantages over traditional joint replacement with stemmed humeral components, in terms of bone preservation and improved joint kinematics.

This study aimed to determine if humeral reaming instruments produce a thermal insult to subchondral bone during TSR. This was tested in vivo on 13 patients (8 with rheumatoid arthritis and 5 with osteoarthritis) with a single reaming system and in vitro with three different humeral reaming systems on saw bone models. Real-time infrared thermal video imaging was used to assess the temperatures generated.

Synthes Epoca instruments generated average temperatures of 40.7°^C (SD 0.9°^C) in the rheumatoid group and 56.5°^C (SD 0.87°^C) in the osteoarthritis group (p = 0.001). Irrigation with room temperature saline cooled the humeral head to 30°^C (SD 1.2°^C). Saw bone analysis generated temperatures of 58.2°^C (SD 0.79°^C) in the Synthes (Epoca) 59.9°^C (SD 0.81°^C) in Biomet (Copeland) and 58.4°^C (SD 0.88°^C) in the Depuy (CAP) reamers (p=0.12).

Humeral reaming with power driven instruments generates considerable temperatures both in vivo and in vitro. This paper demonstrates that a significant thermal effect beyond the 47°^C threshold needed to induce osteonecrosis is observed with humeral reamers, with little variation seen between manufacturers. Irrigation with room temperature saline cools the reamed bone to physiological levels, and should be performed regularly during this step in TSR.

Aim

Evaluate the outcome and complications of anterior pubic symphysis plating in the stabilisation of traumatic anterior pelvic ring injuries.

There is controversy regarding the optimum method of stabilising traumatic anterior pelvic ring injuries. This study aimed to evaluate the role of pubic symphysis plating.

Long-term prospective RCT comparing hemiarthroplasty (HEMI) and total hip arthroplasty (THA) for the treatment of intracapsular neck of femur fracture.

81 previously mobile, independent, orientated patients were randomised to receive THA or HEMI after sustaining a displaced neck of femur fracture. Patients were followed up with radiographs, Oxford hip score (OHS), SF-36 scores and their walking distance.

At a mean follow up of 8.7 years, overall mortality following THA was 32.5% compared to 51.2% following HEMI (p=0.09). Following THA, patients died after a mean of 63.6 months compared to 45 months following HEMI (p=0.093). Patients with THA walked further and had better physical function. No HEMIs dislocated but three (7.5%) THAs did. Four (9.8%) HEMI patients were revised to THA, but only one (2.5%) THA required revision. All surviving HEMI patients had acetabular erosion and all surviving THA patients had wear of the cemented polyethylene cup.

Patients with THA have better function in the medium-term and survive longer.

Metal-on-metal resurfacing offers an alternative strategy to hip replacement in the young active patient with severe osteoarthritis of the hip. The aim of this study was to compare functional outcomes, failure rates and impending revisions in hybrid total hip arthroplasties (THAs) and Birmingham Hip Resurfacings (BHRs) in young active patients.

We compared the 5-7 year clinical and radiological results of the metal-on-metal BHR with hybrid THA in two groups of 54 hips each, matched for sex, age, body mass index and activity. Function was excellent in both groups as measured by the Oxford hip score (median 13 in the BHRs and 14 in the THAs, p=0.14), but the resurfacings had higher UCLA activity scores (median 9 v 7, p=0.001) and better EuroQol quality of life scores (0.90 v 0.78, p=0.003). The THAs had a revision or intention to revise rate of 8% and the BHRs 6%. Both groups demonstrated impending failure on surrogate end-points. 12% of THAs had polyethylene wear and osteolysis under observation, and there was femoral component migration in 8% of resurfacings. Polyethylene wear was present in 48% of hybrid hips without osteolysis. Of the femoral components in the resurfacing group which had not migrated, 66% had radiological changes of unknown significance (classification proposed).

In conclusion, the early to mid-term results of resurfacing with the BHR appear at least as good as those of hybrid THA. Only by longer term follow-up will we establish whether the change of practice recorded here represents a true advance.

Introduction: We report on the long-term follow up of a previously published randomised controlled trial comparing Hemiarthroplasty (HEMI) and total hip arthroplasty (THA) for the treatment of intracapsular fracture neck of femur.

Methods: In this prospectively randomized study, 81 patients who had been mobile and lived independently and who sustained a displaced fracture of the femoral neck were randomized to receive either a fixed acetabular component THA or HEMI. The mean age of the study group was 75 years at fracture. All patients received the same cemented collarless tapered femoral stem and all procedures were performed through a transgluteal approach. Patients were followed up with radiographs, Oxford hip score (OHS), SF-36, Euroqol and their walking distance.

Results: At a mean follow-up of 8.6 years (7.18 to 10.27), 19 HEMI patients and 27 THA were alive (p=0.042). The mean walking distance of patients after HEMI was 600m and the OHS 21. After THA, the mean walking distance was 1200m and the OHS was 22. Both groups had a deterioration of their OHS over time. There were no significant differences between the groups with respect to both physical and mental component SF-36 scores and Euroqol visual analogue scores.

Of the survivors four of the HEMI group were revised to total hip arthroplasty. One patient had been revised in the THA group. Radiographically six of seven patients in the HEMI group had evidence of acetabular erosion and 13 of 15 patients in the THA group had a lucency around their acetabular component.

Discussion: Patients with THA walked further and survived longer. After a mean of nine years follow up there was no difference with respect to function as measured by OHS, Euroqol and SF-36 scores.

Introduction: We compared the eight- to ten-year clinical and radiological results of the metal-on-metal Birmingham hip resurfacing (BHR) with a hybrid total hip arthroplasty (HYBRID) in two groups of 54 hips, previously matched for gender, age, body mass index and activity level.

Method: Patients were followed up in outpatients and function assessed by using the Oxford Hip Score, UCLA activity score and Euroqol score. Radiographs were assessed for osteolysis and wear. BHR were also assessed for the presence of a pedestal sign around the femoral component.

Results: The mean follow up of the BHR group was 9 years (8.17 to 10.33) and for hybrids 10 (7.53 to 14.5). Four patients had died in the hybrid group and one in the BHR. Four were lost to follow up in each group. The revision rate in the BHR group was 9.25% verses 18% in the Hybrid, a further eight patients in the hybrid group have evidence of wear and osteolysis and are intended for revision (p=0.008). One patient in the BHR group was explored for late onset sciatic nerve palsy. All patients in the hybrid group had evidence of polyethylene wear, mean 1.24mm (0.06–3.03). 90% of the BHR group had evidence of a pedestal sign.

Satisfactory function was shown in both groups. There was no significant difference between groups with respect to the OHS but the UCLA score was superior in the BHR group (p=0.008). There was no significant difference for Euroqol visual analogue score. 56% of hybrids were delighted with their hip replacement verses 65% of BHR patients.

Discussion: After ten years the hip resurfacing patients were still more active and had a lower revision burden than the hybrid hip replacements. Both groups showed worrying radiological evidence of change with long-term follow-up.

Aims: To determine the incidence and pattern of pain in patients with displaced pelvic ring injuries treated surgically. To investigate the link between pain and neurological injury.

Methods: All patients with pelvic ring fractures treated surgically were contacted by a postal questionnaire. Assessment was made from validated pain scores, pain maps, a Visual Analog Scale (VAS) and correlated with outcome scores including SF36 and Euroqol. Injuries were classified using the Young and Burgess (YB) classification.

Results: There was a response rate of 85% (151 of 178 patients). Average age at injury was 40 yrs (16–74 yrs). Average follow up was 5.3yrs (1–12 yrs). 72% were male. There were 31% Antero-Posterior Compression (APC) injuries, 37% Lateral Compression (LC) injuries and 32% Vertical Shear (VS) injuries. 76% of all patients reported activity related pain; 70% of APC, 73% of LC and 86% of VS injuries (p=0.05, Chi-squared test). These results correlated directly with the pain domain of the Euroqol tool. There were however no statistically significant differences in the interference of pain with work (SF36) or the VAS between injury classes. There was a 15% prevalence of neurological injury in the cohort (9% of APC, 11% of LC and 27% of VS injuries; p=0.03 Chi-squared test). There were no statistically significant differences in the prevalence of moderate to severe pain (Euroqol) or the VAS between those with and without significant neurological injury. The presence of neurological injury significantly affected return to employment but not return to sports or social activities.

Conclusions: These results illustrate the prevalence of significant morbidity in patients with surgically treated pelvic ring fractures. Presence of pain could be linked to injury category but a link with neurological injury was not obvious. This can help give prognostic information to patients suffering displaced pelvic ring injuries requiring surgical reconstruction.

Aims: To determine the incidence and pattern of sexual dysfunction in patients with displaced pelvic ring injuries treated surgically. To investigate a link between sexual and urological dysfunction.

Methods: All patients with pelvic ring fractures treated surgically were contacted by a postal questionnaire. Sexual function was assessed using elements of the validated Sexual Function Questionnaire. Patients were also asked specifically about new-onset sexual and urological dysfunction. Injuries were classified using the Young and Burgess (YB) classification.

Results: There was a response rate of 85% (151 of 178 patients). Average age at injury was 40 yrs (16–74 yrs). Average follow up was 5.3yrs (1–12 yrs). 72% were male.

31% were Antero-Posterior Compression (APC) injuries, 37% Lateral Compression (LC) injuries and 32% Vertical Shear (VS) injuries.

32% of all patients reported significant new sexual problems (36% of males and 24% of females). Of the males, 31% reported erectile dysfunction (12% absolute impotence), 32% reported decreased arousal and 21% reported ejaculatory problems. Of the females, 16% reported decreased arousal, 5% reported anorgasmia and 3% reported painful orgasms. There were no reported cases of dyspareunia in the female patients.

41% of APC, 15% of LC and 39% of VS injuries reported significant new sexual problems (p=0.02, Chi-squared test).

There was a 12% prevalence of significant new urological dysfunction in the entire cohort, with 27% of those with sexual dysfunction also reporting urological dysfunction. This compares with a 5% prevalence of urological dysfunction in patients without sexual dysfunction (p< 0.0001, Chi-squared test).

Conclusions: This large outcome study of UK patients illustrates the significant prevalence of new onset sexual dysfunction in patients with surgically treated pelvic ring fractures. The results also suggest an association between sexual and urological dysfunction. This can help give prognostic information to patients and plan service provision.

We aimed to determine multi-modality outcomes in surgically treated patients with high energy pelvic ring injuries. A retrospective cohort study of all patients with pelvic ring fractures treated surgically within our specialist tertiary referral unit was undertaken between 1994 and 2007. Case-notes and radiographs were reviewed and patients were contacted by postal questionnaire. Outcome measures were return to work, return to pre-injury sports and social activities, and the Short Form-36 (SF-36) outcome tool. Injuries were classified using the Young and Burgess (YB) classifications.

There was a response rate of 70% (145 of 209 patients), 74% of the study subjects were male. Average age at injury was 40 yrs (16–74 yrs). Average follow up was 5.3 yrs (1–12 yrs). There were 45 Antero-Posterior Compression (APC) injuries, 51 Lateral Compression (LC) injuries and 49 Vertical Shear (VS) injuries. 58% of the APC injuries had returned to work (including changed roles at work), compared with 68% of the LC injuries and 51% of the VS injuries. 27% of the APC injuries had returned to their pre-injury sports, compared with 39% of the LC and 33% of the VS injuries. 64% of the APC injuries had returned to their pre-injury social activities compared with 77% of the LC and 49% of the VS injuries.

The SF-36 average Physical Functioning Score was better for the LC group (73.2) than the APC (61.7) and VS (63.3) groups. This general trend was repeated when the General Health and Social Functioning scores were reviewed.

These results illustrate the long-term morbidity associated with pelvic ring injuries and relationship with injury subtypes. The LC injuries appear to have better outcomes with all outcome measures than APC and VS injuries. Further studies are underway to look at other factors and their relationship to outcomes.

The incidence of degenerative scoliosis in the lumbar spine is not known. In the ageing population deformity may coexist or cause stenosis. MRI gives limited information on this important parameter in the treatment of stenosis. The aim of this study was to highlight the incidence of coronal abnormalities of the lumbar spine dependent on age in a large population of patients.

We reviewed all abdominal radiographs performed in our hospital over ten months. 2276 radiographs were analysed for degenerative lumbar scoliosis and lateral vertebral slips in patients who are over 20 years. Evidence of osteoarthritis of the spine was also documented. Radiographs were included if the inferior border of T12 to the superior border of S1 was visualised and no previous spinal surgery was evident (metal work).

2233 (98%) radiographs were included. 48% of patients were female. The incidence of degenerative lumbar scoliosis, lateral listhesis and osteoarthritis increased with age. Degenerative scoliosis was present in 1.6% of 30–39 year olds increasing every decade to 29.7% of patients 90 years or older. In all age groups curves were more frequent and had greater average Cobb angles in female patients.

Degenerative lumbar scoliosis starts to appear in the third decade of life increasing in frequency every decade thereafter, affecting almost a third of patients in the ninth decade. It is more common in female patients and has a greater magnitude. Deformity may be even greater on standing views and is important to recognise in all patients that are undergoing lumbar spinal decompressive surgery. A failure to do so may lead to inferior results or the need for further surgery.

Introduction: Injuries to the bony pelvis are a significant group of injuries with often serious implications. The close proximity of the bony pelvis to vital organs, it’s involvement in weight bearing and ambulation, and the high energy mechanisms usually required to produce these injuries produces a variety of injury patterns, associated injuries and possible outcomes.

Aims: To determine the long-term functional outcomes of displaced pelvic ring injuries treated surgically in the United Kingdom

Methods: All patients with pelvic ring fractures treated surgically were contacted by postal questionnaire. Outcomes were measured using the SF-36, as well as ad-hoc tools including return to work and sporting activities. Injuries were classified using the Young and Burgess (YB) classification system.

Results: There was a response rate of 70% (145 of 209 patients). Average age at injury was 40 yrs (16–74 yrs). Average follow up was 5.3yrs (1–12 yrs).

There were 45 Antero-Posterior Compression (APC) injuries, 51 Lateral Compression (LC) injuries and 49 Vertical Shear (VS) injuries.

69% of the LC injuries had returned to some form of employment, compared with 58% of the APC injuries and 51% of the VS. 39% of the LC injuries had returned to their pre-injury sporting activities, compared with 27% of the APC and 33% of the VS.

The average Physical Functioning Score of the SF-36 outcome tool was 73.2 for the LC injuries, 61.7 for the APC injuries and 63.3 for the VS injuries (scale 0–100, 100 representing best status). These trends were mirrored in the other outcome domains of the SF-36 tool.

Conclusions: These results illustrate the long-term morbidity associated with pelvic ring injuries and relationship with injury subtypes. LC injuries appeared to perform better than APC and VS injuries in all outcome measures utilized. These findings may aid in determining the prognosis and provision of services for patients with pelvic ring injuries.

Introduction: The incidence of degenerative scoliosis in the lumbar spine is not known. In the ageing population deformity may coexist or cause stenosis. MRI gives limited information on this important parameter and is often the only investigation used pre-operatively in the treatment of stenosis. The aim of this study was to highlight the incidence of coronal abnormalities of the lumbar spine dependent on age in a large population of patients requiring abdominal and KUB radiographs at our institution.

Method: We reviewed all abdominal and KUB radiographs performed in our hospital in the first ten months from the introduction of our digital PACS system. 2276 radiographs were analysed for the incidence of degenerative lumbar scoliosis and lateral vertebral slips in patients who are ≥ 20 years old, in ten-year age ranges. Evidence of osteoarthritis of the spine was also documented. Radiographs were included if the inferior border of T12 to the superior border of S1 was visualised and no previous spinal surgery was evident (metal work/laminectomy).

Results: 2233 (98%) radiographs were analysed. 48% of patients were female. The youngest patient was 20 and the oldest 101 years. The incidence of degenerative lumbar scoliosis, lateral listhesis and osteoarthritis increased with age.

In all age groups curves were more frequent and had greater average Cobb angles in female patients except in the 30–39 year olds–where the males equalled females in frequency and had the greatest Cobb angles.

Conclusions: Degenerative lumbar scoliosis starts to appear in the third decade of life and increases in frequency every decade thereafter, affecting almost a third of patients in the ninth decade. It is more common in female patients and has a greater magnitude. Deformity may be even greater on standing views and is important to recognise in all patients that are undergoing lumbar spinal decompressive surgery. A failure to do so may lead to inferior results or the need for further surgery.

Objective: An anatomical study to describe the radiographic pattern of canal, foraminal and lateral recess stenosis in degenerative lumbar stenosis associated with open and closed subluxations of the lumbar spine.

Introduction: Degenerative lumbar scoliosis is a three-dimensional deformity frequently associated with facet joint subluxation. It is suggested that the causative mechanism of open subluxation is vertebral rotation, whereas closed subluxation is driven by erosion of the convex facet joint. Patients with degenerative lumbar scoliosis are predominantly symptomatic on standing. However, standing MRI scans are not currently feasible to investigate this dynamic problem, therefore an accurate interpretation of the standing and lateral radiographs is essential to effectively treat this condition. We have undertaken a study to compare standing radiographs with supine MRI to determine the pattern of nerve root entrapment with open and closed facet joint dislocations in DLS.

Methods: Plain radiographs and MRI scans of 35 consecutive patients with de novo degenerative lumbar scoliosis (average age 72 years) were evaluated. Radiographic measurements included the angle of the dislocation, degree of translation, position of osteophytes, vertebral rotation and the degree and location of any stenosis present on the axial MRI images.

Results: Open dislocations were associated with a pre-dominant contralateral lateral recess and/or foraminal stenosis in 74% of cases. Closed dislocations were associated with ipsilateral lateral recess and/or foraminal stenosis in 82% of cases. Both open and closed dislocations had a similar degree of vertebral rotation.

67% of open subluxations occurred at L3/4. In closed subluxations the most frequent level involved was LI/2 (53% of cases). Open dislocations are located closest to the apex of the curve, with closed dislocations being more peripheral. The curve was noted to rotate towards the apex.

Conclusion: Open and closed subluxations of the lumbar spine result in different, but predictable, patterns of stenosis. The findings are important in the diagnosis and planning of treatment in patients with lumbar spinal stenosis, when associated with degenerative scoliosis and lateral spondylolisthesis.

Objective: An anatomical study to describe the radiographic pattern of canal, foraminal and lateral recess stenosis in degenerative lumbar stenosis associated with open and closed subluxations of the lumbar spine.

Introduction: Degenerative lumbar scoliosis is a three-dimensional deformity frequently associated with facet joint subluxation. It is suggested that the causative mechanism of open subluxation is vertebral rotation, whereas closed subluxation is driven by erosion of the convex facet joint.

Methods: Plain radiographs and MRI scans of 40 consecutive patients with de novo degenerative lumbar scoliosis (average age 72 years) were evaluated. Radiographic measurements included the angle of the dislocation, degree of translation, position of osteophytes, vertebral rotation and the degree and location of any stenosis present on the axial MRI images.

Results: Open dislocations were associated with a contralateral lateral recess and/or foraminal stenosis in 85.7% of cases. Closed dislocations were associated with ipsilateral lateral recess and/or foraminal stenosis in 83.3% of cases. Open dislocations had a greater degree of vertebral rotation than closed (10.9° v 7.8°).

56% of open subluxations occurred at L3/4. In closed subluxations the most frequent level involved was LI/2 (36% of cases). Where both subluxations coexisted, the open subluxation was more proximal.

Conclusion: Open and closed subluxations of the lumbar spine result in different, but predictable, patterns of stenosis. The findings are important in the diagnosis and planning of treatment in patients with lumbar spinal stenosis, when associated with degenerative scoliosis and lateral spondylolisthesis.

There is much debate about the nature and extent of deformities in the proximal femur in children with cerebral palsy. Most authorities accept that increased femoral anteversion is common, but its incidence, severity and clinical significance are less clear. Coxa valga is more controversial and many authorities state that it is a radiological artefact rather than a true deformity.

We measured femoral anteversion clinically and the neck-shaft angle radiologically in 292 children with cerebral palsy. This represented 78% of a large, population-based cohort of children with cerebral palsy which included all motor types, topographical distributions and functional levels as determined by the gross motor function classification system.

The mean femoral neck anteversion was 36.5° (11° to 67.5°) and the mean neck-shaft angle 147.5° (130° to 178°). These were both increased compared with values in normally developing children. The mean femoral neck anteversion was 30.4° (11° to 50°) at gross motor function classification system level I, 35.5° (8° to 65°) at level II and then plateaued at approximately 40.0° (25° to 67.5°) at levels III, IV and V. The mean neck-shaft angle increased in a step-wise manner from 135.9° (130° to 145°) at gross motor function classification system level I to 163.0° (151° to 178°) at level V. The migration percentage increased in a similar pattern and was closely related to femoral deformity.

Based on these findings we believe that displacement of the hip in patients with cerebral palsy can be explained mainly by the abnormal shape of the proximal femur, as a result of delayed walking, limited walking or inability to walk. This has clinical implications for the management of hip displacement in children with cerebral palsy.