The recognition of hips at risk of displacement in children with cerebral palsy (CP) is a difficult problem for the orthopaedic surgeon. The Gross Motor Function Classification System (GMFCS) and head–shaft angle (HSA) are prognostic factors for hip displacement. However, reference values for HSA are lacking. This study describes and compares the development of HSA in normal hips and children with CP.

We selected 33 children from a retrospective cohort with unilateral developmental dysplasia of the hip (DDH) (five boys, 28 girls) and 50 children (35 boys, 15 girls) with CP with GMFCS levels II to V. HSA of normal developing hips was measured at the contralateral hip of unilateral DDH children (33 hips) and HSA of CP children was measured in both hips (100 hips). Measurements were taken from the radiographs of the children at age two, four and seven years. The normal hip HSA decreased by 2° per year (p < 0.001). In children with CP with GMFCS levels II and III HSA decreased by 0.6° (p = 0.046) and 0.9° (p = 0.049) per year, respectively. The HSA did not alter significantly in GMFCS levels IV and V.

Between the ages of two and eight years, the HSA decreases in normal hips and CP children with GMFCS level, II to III but does not change in GMFCS levels IV to V. As HSA has a prognostic value for hip displacement, these reference values may help the orthopaedic surgeon to predict future hip displacement in children with CP.

Cite this article: Bone Joint J 2015;97-B:1291–5.

In Japan, osteoarthritis (OA) of the hip secondary to acetabular dysplasia is very common, and there are few data concerning the pathogeneses and incidence of femoroacetabular impingement (FAI). We have attempted to clarify the radiological prevalence of painful FAI in a cohort of Japanese patients and to investigate the radiological findings. We identified 176 symptomatic patients (202 hips) with Tönnis grade 0 or 1 osteoarthritis, whom we prospectively studied between August 2011 and July 2012. There were 61 men (65 hips) and 115 women (137 hips) with a mean age of 51.8 years (11 to 83). Radiological analyses included the α-angle, centre–edge angle, cross-over sign, pistol grip deformity and femoral head neck ratio. Of the 202 hips, 79 (39.1%) had acetabular dysplasia, while 80 hips (39.6%) had no known aetiology. We found evidence of FAI in 60 hips (29.7%). Radiological FAI findings associated with cam deformity were the most common. There was a significant relationship between the pistol grip deformity and both the α-angle (p < 0.001) and femoral head–neck ratio (p = 0.024). Radiological evidence of symptomatic FAI was not uncommon in these Japanese patients.

Cite this article: Bone Joint J 2013;96-B:172–6.

It has recently been reported that the transverse acetabular ligament (TAL) is helpful in determining the position of the acetabular component in total hip replacement (THR). In this study we used a computer-assisted navigation system to determine whether the TAL is useful as a landmark in THR. The study was carried out in 121 consecutive patients undergoing primary THR (134 hips), including 67 dysplastic hips (50%). There were 26 men (29 hips) and 95 women (105 hips) with a mean age of 60.2 years (17 to 82) at the time of operation. After identification of the TAL, its anteversion was measured intra-operatively by aligning the inferomedial rim of the trial acetabular component with the TAL using computer-assisted navigation. The TAL was identified in 112 hips (83.6%). Intra-observer reproducibility in the measurement of anteversion of the TAL was high, but inter-observer reproducibility was moderate.

Each surgeon was able to align the trial component according to the target value of the angle of anteversion of the TAL, but it was clear that methods may differ among surgeons. Of the measurements of the angle of anteversion of the TAL, 5.4% (6 of 112 hips) were outliers from the safe zone.

In summary, we found that the TAL is useful as a landmark when implanting the acetabular component within the safe zone in almost all hips, and to prevent it being implanted in retroversion in all hips, including dysplastic hips. However, as anteversion of the TAL may be excessive in a few hips, it is advisable to pay attention to individual variations, particularly in those with severe posterior pelvic tilt.

Cite this article: Bone Joint J 2014;96-B:306–11.

The aim of this prospective study was to investigate prematurity as a risk factor for developmental dysplasia of the hip (DDH). The hips of 221 infants (88 female, 133 male, mean age 31.11 weeks; standard deviation (sd) 2.51) who were born in the 34th week of gestation or earlier, and those of 246 infants (118 female, 128 male, mean age 40.22 weeks; sd 0.36) who were born in the 40th week of gestation, none of whom had risk factors for DDH, were compared using physical examination and ultrasound according to the technique of Graf, within one week, after the correction of gestational age to the 40th week after birth or one week since birth, respectively. Both hips of all infants were included in the study. Ortolani’s and Barlow’s tests and restricted abduction were accepted as positive findings on examination. There was a statistically significant difference between pre- and full-term infants, according to the incidence of mature and immature hips (p < 0.001). The difference in the proportion of infants with an α angle < 60° between the two groups was statistically significant (p < 0.001). The incidence of pathological dysplasia (α angle < 50 º) was not significantly different in the two groups (p = 1.000). The Barlow sign was present in two (0.5%) pre-term infants and in 14 (2.8%) full-term infants.

These results suggests that prematurity is not a predisposing factor for DDH.

Cite this article: Bone Joint J 2015; 97-B:716–20

Perthes’ disease is an osteonecrosis of the juvenile hip, the aetiology of which is unknown. A number of comorbid associations have been suggested that may offer insights into aetiology, yet the strength and validity of these are unclear. This study explored such associations through a case control study using the United Kingdom General Practice Research database. Associations investigated were those previously suggested within the literature. A total of 619 cases of Perthes’ disease were included, as were 2544 controls. The risk of Perthes’ disease was significantly increased with the presence of congenital anomalies of the genitourinary and inguinal region, such as hypospadias (odds ratio (OR) 4.04 (95% confidence interval (CI) 1.41 to 11.58)), undescended testis (OR 1.83 (95% CI 1.12 to 3.00)) and inguinal herniae (OR 1.79 (95% CI 1.02 to 3.16)). Attention deficit hyperactivity disorder was not associated with Perthes’ disease (OR 1.01 (95% CI 0.48 to 2.12)), although a generalised behavioural disorder was (OR 1.55 (95% CI 1.10 to 2.17)). Asthma significantly increased the risk of Perthes’ disease (OR 1.44 (95% CI 1.17 to 1.76)), which remained after adjusting for oral/parenteral steroid use.

Perthes’ disease has a significant association with congenital genitourinary and inguinal anomalies, suggesting that intra-uterine factors may be critical to causation. Other comorbid associations may offer insight to support or refute theories of pathogenesis.

We investigated differences in the location and mode of labral tears between dysplastic hips and hips with femoroacetabular impingement (FAI). We also investigated the relationship between labral tear and adjacent cartilage damage. We retrospectively studied 72 symptomatic hips (in 68 patients: 19 men and 49 women) with radiological evidence of dysplasia or FAI on high-resolution CT arthrography. The incidence and location of labral tears and modes of tear associated with the base of the labrum (Mode 1) or body of the labrum (Mode 2) were compared among FAI, mildly dysplastic and severely dysplastic hips. The locations predominantly involved with labral tears were different in FAI and mild dysplastic hips (anterior and anterosuperior zones) and in severely dysplastic hips (anterosuperior and superior zones) around the acetabulum. Significant differences were observed in the prevalence of Mode 1 versus Mode 2 tears in FAI hips (72% (n = 13) vs 28% (n = 5)) and severe dysplastic hips (25% (n = 2) vs 75% (n = 6)). The frequency of cartilage damage adjacent to Mode 1 tears was significantly higher (42% (n = 14)) than that adjacent to Mode 2 tears (14% (n = 3)).

Hip pathology is significantly related to the locations and modes of labral tears. Mode 1 tears may be a risk factor for the development of adjacent acetabular cartilage damage.

Cite this article: Bone Joint J 2013;95-B:1320–5.

The February 2015 Hip & Pelvis Roundup³⁶⁰ looks at: Hip arthroplasty in Down syndrome; Bulk femoral autograft successful in acetabular reconstruction; Arthroplasty follow-up: is the internet the solution?; Total hip arthroplasty following acetabular fracture; Salvage arthroplasty following failed hip internal fixation; Bone banking sensible financially and clinically; Allogenic blood transfusion in arthroplasty.

In this study we used subject-specific finite element analysis to investigate the mechanical effects of rotational acetabular osteotomy (RAO) on the hip joint and analysed the correlation between various radiological measurements and mechanical stress in the hip joint.

We evaluated 13 hips in 12 patients (two men and ten women, mean age at surgery 32.0 years; 19 to 46) with developmental dysplasia of the hip (DDH) who were treated by RAO.

Subject-specific finite element models were constructed from CT data. The centre–edge (CE) angle, acetabular head index (AHI), acetabular angle and acetabular roof angle (ARA) were measured on anteroposterior pelvic radiographs taken before and after RAO. The relationship between equivalent stress in the hip joint and radiological measurements was analysed.

The equivalent stress in the acetabulum decreased from 4.1 MPa (2.7 to 6.5) pre-operatively to 2.8 MPa (1.8 to 3.6) post-operatively (p < 0.01). There was a moderate correlation between equivalent stress in the acetabulum and the radiological measurements: CE angle (R = –0.645, p < 0.01); AHI (R = –0.603, p < 0.01); acetabular angle (R = 0.484, p = 0.02); and ARA (R = 0.572, p < 0.01).

The equivalent stress in the acetabulum of patients with DDH decreased after RAO. Correction of the CE angle, AHI and ARA was considered to be important in reducing the mechanical stress in the hip joint.

Cite this article: Bone Joint J 2015;97-B:492–7.

We report the kinematic and early clinical results of a patient- and observer-blinded randomised controlled trial in which CT scans were used to compare potential impingement-free range of movement (ROM) and acetabular component cover between patients treated with either the navigated ‘femur-first’ total hip arthroplasty (THA) method (n = 66; male/female 29/37, mean age 62.5 years; 50 to 74) or conventional THA (n = 69; male/female 35/34, mean age 62.9 years; 50 to 75). The Hip Osteoarthritis Outcome Score, the Harris hip score, the Euro-Qol-5D and the Mancuso THA patient expectations score were assessed at six weeks, six months and one year after surgery. A total of 48 of the patients (84%) in the navigated ‘femur-first’ group and 43 (65%) in the conventional group reached all the desirable potential ROM boundaries without prosthetic impingement for activities of daily living (ADL) in flexion, extension, abduction, adduction and rotation (p = 0.016). Acetabular component cover and surface contact with the host bone were > 87% in both groups. There was a significant difference between the navigated and the conventional groups’ Harris hip scores six weeks after surgery (p = 0.010). There were no significant differences with respect to any clinical outcome at six months and one year of follow-up. The navigated ‘femur-first’ technique improves the potential ROM for ADL without prosthetic impingement, although there was no observed clinical difference between the two treatment groups.

Cite this article: Bone Joint J 2015; 97-B:890–8.

The February 2015 Children’s orthopaedics Roundup³⁶⁰ looks at: Hip dislocation in children with CTEV: two decades of experience; Population-based prevention of DDH in cerebral palsy: 20 years’ experience; Shoulder derotation in congenital plexus palsy; Back pain in the paediatric population: could MRI be the answer?; Intercondylar fracture of the humerus in children; The Dunn osteotomy in SUFE; Radiocapitellar line a myth!; Do ‘flatfooted’ children suffer?

Despite the worldwide usage of the cemented Contemporary acetabular component (Stryker), no published data are available regarding its use in patients aged < 50 years. We undertook a mid- to long-term follow-up study, including all consecutive patients aged < 50 years who underwent a primary total hip replacement using the Contemporary acetabular component with the Exeter cemented stem between January 1999 and January 2006. There were 152 hips in 126 patients, 61 men and 65 women, mean age at surgery 37.6 years (16 to 49 yrs). One patient was lost to follow-up.

Mean clinical follow-up of all implants was 7.6 years (0.9 to 12.0). All clinical questionnaire scores, including Harris hip score, Oxford hip score and several visual analogue scales, were found to have improved. The eight year survivorship of all acetabular components for the endpoints revision for any reason or revision for aseptic loosening was 94.4% (95% confidence interval (CI) 89.2 to 97.2) and 96.4% (95% CI 91.6 to 98.5), respectively. Radiological follow-up was complete for 146 implants. The eight year survival for the endpoint radiological loosening was 93.1% (95% CI 86.2 to 96.6). Three surviving implants were considered radiologically loose but were asymptomatic. The presence of acetabular osteolysis (n = 17, 11.8%) and radiolucent lines (n = 20, 13.9%) in the 144 surviving cups indicates a need for continued observation in the second decade of follow-up in order to observe their influence on long-term survival.

The clinical and radiological data resulting in a ten-year survival rate > 90% in young patients support the use of the Contemporary acetabular component in this specific patient group.

Cite this article: Bone Joint J 2013;95-B:1617–25.

Femoral stem version has a major influence on impingement and early post-operative stability after total hip arthroplasty (THA).

The main objective of this study was to evaluate the validity of a novel radiological method for measuring stem version. Anteroposterior (AP) radiographs and three-dimensional CT scans were obtained for 115 patients (female/male 63/72, mean age 62.5 years (50 to 75)) who had undergone minimally invasive, cementless THA. Stem version was calculated from the AP hip radiograph by rotation-based change in the projected prosthetic neck–shaft (NSA*) angle using the mathematical formula ST = arcos [tan (NSA*) / tan (135)]. We used two independent observers who repeated the analysis after a six-week interval. Radiological measurements were compared with 3D-CT measurements by an independent, blinded external institute.

We found a mean difference of 1.2° (sd 6.2) between radiological and 3D-CT measurements of stem version. The correlation between the mean radiological and 3D-CT stem torsion was r = 0.88 (p < 0.001). The intra- (intraclass correlation coefficient ≥ 0.94) and inter-observer agreement (mean concordance correlation coefficient = 0.87) for the radiological measurements were excellent.

We found that femoral tilt was associated with the mean radiological measurement error (r = 0.22, p = 0.02).

The projected neck–shaft angle is a reliable method for measuring stem version on AP radiographs of the hip after a THA. However, a highly standardised radiological technique is required for its precise measurement.

Cite this article: Bone Joint J 2015; 97-B:306–11.

Construction of a functional skeleton is accomplished through co-ordination of the developmental processes of chondrogenesis, osteogenesis, and synovial joint formation. Infants whose movement in utero is reduced or restricted and who subsequently suffer from joint dysplasia (including joint contractures) and thin hypo-mineralised bones, demonstrate that embryonic movement is crucial for appropriate skeletogenesis. This has been confirmed in mouse, chick, and zebrafish animal models, where reduced or eliminated movement consistently yields similar malformations and which provide the possibility of experimentation to uncover the precise disturbances and the mechanisms by which movement impacts molecular regulation. Molecular genetic studies have shown the important roles played by cell communication signalling pathways, namely Wnt, Hedgehog, and transforming growth factor-beta/bone morphogenetic protein. These pathways regulate cell behaviours such as proliferation and differentiation to control maturation of the skeletal elements, and are affected when movement is altered. Cell contacts to the extra-cellular matrix as well as the cytoskeleton offer a means of mechanotransduction which could integrate mechanical cues with genetic regulation. Indeed, expression of cytoskeletal genes has been shown to be affected by immobilisation. In addition to furthering our understanding of a fundamental aspect of cell control and differentiation during development, research in this area is applicable to the engineering of stable skeletal tissues from stem cells, which relies on an understanding of developmental mechanisms including genetic and physical criteria. A deeper understanding of how movement affects skeletogenesis therefore has broader implications for regenerative therapeutics for injury or disease, as well as for optimisation of physical therapy regimes for individuals affected by skeletal abnormalities.

Cite this article: Bone Joint Res 2015;4:105–116

We evaluated an operative technique, described by the Exeter Hip Unit, to assist accurate introduction of the femoral component. We assessed whether it led to a reduction in the rate of leg-length discrepancy after total hip arthroplasty (THA).

A total of 100 patients undergoing THA were studied retrospectively; 50 were undertaken using the test method and 50 using conventional methods as a control group. The groups were matched with respect to patient demographics and the grade of surgeon. Three observers measured the depth of placement of the femoral component on post-operative radiographs and measured the length of the legs.

There was a strong correlation between the depth of insertion of the femoral component and the templated depth in the test group (R = 0.92), suggesting accuracy of the technique. The mean leg-length discrepancy was 5.1 mm (0.6 to 21.4) pre-operatively and 1.3 mm (0.2 to 9.3) post-operatively. There was no difference between Consultants and Registrars as primary surgeons. Agreement between the templated and post-operative depth of insertion was associated with reduced post-operative leg-length discrepancy. The intra-class coefficient was R ≥ 0.88 for all measurements, indicating high observer agreement. The post-operative leg-length discrepancy was significantly lower in the test group (1.3 mm) compared with the control group (6.3 mm, p < 0.001).

The Exeter technique is reproducible and leads to a lower incidence of leg-length discrepancy after THA.

Cite this article: Bone Joint J 2015;97-B:154–9.

We describe our experience in the reduction of dislocation of the hip secondary to developmental dysplasia using ultrasound-guided gradual reduction using flexion and abduction continuous traction (FACT-R). During a period of 13 years we treated 208 Suzuki type B or C complete dislocations of the hip in 202 children with a mean age of four months (0 to 11). The mean follow-up was 9.1 years (five to 16). The rate of reduction was 99.0%. There were no recurrent dislocations, and the rate of avascular necrosis of the femoral head was 1.0%. The rate of secondary surgery for residual acetabular dysplasia was 19.2%, and this was significantly higher in those children in whom the initial treatment was delayed or if other previous treatments had failed (p = 0.00045). The duration of FACT-R was significantly longer in severe dislocations (p = 0.001) or if previous treatments had failed (p = 0.018).

This new method of treatment is effective and safe in these difficult cases and offers outcomes comparable to or better than those of standard methods.

Cite this article: Bone Joint J 2015;97-B:405–11.

Hip arthroscopy is particularly attractive in children as it confers advantages over arthrotomy or open surgery, such as shorter recovery time and earlier return to activity. Developments in surgical technique and arthroscopic instrumentation have enabled extension of arthroscopy of the hip to this age group. Potential challenges in paediatric and adolescent hip arthroscopy include variability in size, normal developmental change from childhood to adolescence, and conditions specific to children and adolescents and their various consequences. Treatable disorders include the sequelae of traumatic and sports-related hip joint injuries, Legg–Calve–Perthes’ disease and slipped capital femoral epiphysis, and the arthritic and septic hip. Intra-articular abnormalities are rarely isolated and are often associated with underlying morphological changes.

This review presents the current concepts of hip arthroscopy in the paediatric and adolescent patient, covering clinical assessment and investigation, indications and results of the experience to date, as well as technical challenges and future directions.

The December 2014 Children’s orthopaedics Roundup³⁶⁰ looks at: predicting drift in supracondylar fractures; do normal hips dislocate?; the burden of trampoline fractures; muscle eversion activity is strongly predictive of outcome in CTEV; the modified Dunn osteotomy; plaster and moulded casts; and psychology and fractures.

We report the clinical and radiographic outcomes of 208 consecutive femoral revision arthroplasties performed in 202 patients (119 women, 83 men) between March 1991 and December 2007 using the X-change Femoral Revision System, fresh-frozen morcellised allograft and a cemented polished Exeter stem. All patients were followed prospectively. The mean age of the patients at revision was 65 years (30 to 86). At final review in December 2013 a total of 130 patients with 135 reconstructions (64.9%) were alive and had a non re-revised femoral component after a mean follow-up of 10.6 years (4.7 to 20.9). One patient was lost to follow-up at six years, and their data were included up to this point. Re-operation for any reason was performed in 33 hips (15.9%), in 13 of which the femoral component was re-revised (6.3%). The mean pre-operative Harris hip score was 52 (19 to 95) (n = 73) and improved to 80 (22 to 100) (n = 161) by the last follow-up. Kaplan–Meier survival with femoral re-revision for any reason as the endpoint was 94.9% (95% confidence intervals (CI) 90.2 to 97.4) at ten years; with femoral re-revision for aseptic loosening as the endpoint it was 99.4% (95% CI 95.7 to 99.9); with femoral re-operation for any reason as the endpoint it was 84.5% (95% CI 78.3 to 89.1); and with subsidence ≥ 5 mm it was 87.3% (95% CI 80.5 to 91.8). Femoral revision with the use of impaction allograft bone grafting and a cemented polished stem results in a satisfying survival rate at a mean of ten years’ follow-up.

Cite this article: Bone Joint J 2015; 97-B:771–9.

The February 2013 Children’s orthopaedics Roundup³⁶⁰ looks at: ABC treated with suction and curettage; peri-acetabular osteotomy; cast index; Perthes’ disease associated with accidental injury; brachial plexus birth palsy; MRI assessment of DDH; total meniscectomy; and paediatric septic arthritis.

When performing total hip replacement (THR) in high dislocated hips, the presence of soft-tissue contractures means that most surgeons prefer to use a femoral shortening osteotomy in order to avoid the risk of neurovascular damage. However, this technique will sacrifice femoral length and reduce the extent of any leg-length equalisation. We report our experience of 74 THRs performed between 2000 and 2008 in 65 patients with a high dislocated hip without a femoral shortening osteotomy. The mean age of the patients was 55 years (46 to 72) and the mean follow-up was 42 months (12 to 78). All implants were cementless except for one resurfacing hip implant. We attempted to place the acetabular component in the anatomical position in each hip. The mean Harris hip score improved from 53 points (34 to 74) pre-operatively to 86 points (78 to 95) at final follow-up. The mean radiologically determined leg lengthening was 42 mm (30 to 66), and the mean leg-length discrepancy decreased from 36 mm (5 to 56) pre-operatively to 8.5 mm (0 to 18) postoperatively. Although there were four (5%) post-operative femoral nerve palsies, three had fully resolved by six months after the operation. No loosening of the implant was observed, and no dislocations or infections were encountered.

Total hip replacement without a femoral shortening osteotomy proved to be a safe and effective surgical treatment for high dislocated hips.