We conducted a retrospective study to investigate the effect of femoral bowing on the placement of components in total knee replacement (TKR), with regard to its effect on reestablishing the correct mechanical axis, as we hypothesised that computer-assisted total knee replacement (CAS-TKR) would produce more accurate alignment than conventional TKR. Between January 2006 and December 2009, 212 patients (306 knees) underwent TKR. The conventional TKR was compared with CAS-TKR for accuracy of placement of the components and post-operative alignment, as determined by five radiological measurements. There were significant differences in the reconstructed mechanical axes between the bowed and the non-bowed group after conventional TKR (176.2° (sd 3.4) vs 179.3° (sd 2.1), p < 0.001).

For patients with significant femoral bowing, the reconstructed mechanical axes were significantly closer to normal in the CAS group than in the conventional group (179.2° (sd 1.9) vs 176.2° (sd 3.4), p < 0.001). Femoral bowing resulted in inaccuracy when a conventional technique was used. CAS-TKR provides an effective method of restoring the mechanical axis in the presence of significant femoral bowing.

Four uncemented Symax hip stems were extracted at three weeks and nine, 13 and 32 months, respectively, for reasons other than loosening. The reasons for implant removal were infection in two cases, recurrent dislocation in one and acetabular fracture in one. They were analysed to assess the effect and behaviour of an electrochemically deposited, completely resorbable biomimetic BONIT-hydroxyapatite (HA) coating (proximal part) and a DOTIZE surface treatment (distal part) using qualitative histology, quantitative histomorphometry and scanning electron microscopy (SEM). Early and direct bone-implant bonding with signs of active remodelling of bone and the HA coating were demonstrated by histology and SEM. No loose BONIT-HA particles or delamination of the coating were observed, and there was no inflammation or fibrous interposition at the interface.

Histomorphometry showed bone-implant contact varying between 26.5% at three weeks and 83.5% at 13 months at the HA-coated implant surface. The bone density in the area of investigation was between 24.6% at three weeks and 41.1% at 32 months. The DOTIZE surface treatment of the distal part of the stem completely prevented tissue and bone apposition in all cases, thereby optimising proximal stress transfer.

The overall features of this implant, in terms of geometry and surface texture, suggest a mechanically stable design with a highly active biomimetic coating, resulting in rapid and extensive osseo-integration, exclusively in the metaphyseal part of the stem. Early remodelling of the HA coating does not seem to have a detrimental effect on short-term bone-implant coupling. There were no adverse effects identified from either the BONIT-HA coating or the DOTIZE surface treatment.

The management of joint replacement in lysosomal storage diseases has not been well reported. We present three patients with progressive degenerative changes of the hips who required bilateral total hip replacement in early childhood. The stature of the patients make it essential to have access to appropriately scaled prostheses. Consideration has to be given to associated disorders of the skeleton which must be carefully screened to ensure safety in providing appropriate anaesthesia as well as ensuring that there is no cardiac abnormality. In one patient, a periprosthetic fracture was sustained in one hip in the early post-operative course requiring internal fixation.

The patient made a full recovery and all six hips were clinically and radiologically satisfactory at mid-term review.

This paper reviews the current knowledge relating to the management of adult patients with congenital hip disease. Orthopaedic surgeons who treat these patients with a total hip replacement should be familiar with the arguments concerning its terminology, be able to recognise the different anatomical abnormalities and to undertake thorough pre-operative planning in order to replace the hip using an appropriate surgical technique and the correct implants and be able to anticipate the clinical outcome and the complications.

The radiological evaluation of the anterolateral femoral head is an essential tool for the assessment of the cam type of femoroacetabular impingement. CT, MRI and frog lateral plain radiographs have all been suggested as imaging options for this type of lesion. The alpha angle is accepted as a reliable indicator of the cam type of impingement and may also be used as an assessment for the successful operative correction of the cam lesion.

We studied the alpha angles of 32 consecutive patients with femoroacetabular impingement. The angle measured on frog lateral radiographs using templating tools was compared with that measured on CT scans in order to assess the reliability of the frog lateral view in analysing the alpha angle in cam impingement.

A high interobserver reliability was noted for the assessment of the alpha angle on the frog lateral view with an intraclass correlation coefficient of 0.83. The mean alpha angle measured on the frog lateral view was 58.71° (32° to 83.3°) and that by CT was 65.11° (30° to 102°). A poor intraclass correlation coefficient (0.08) was noted between the measurements using the two systems.

The frog lateral plain radiograph is not reliable for measuring the alpha angle. Various factors may be responsible for this such as the projection of the radiograph, the positioning of the patient and the quality of the image. CT may be necessary for accurate measurement of the alpha angle.

We undertook a study in which 138 female patients with a mean age of 71.2 years (51 to 82) received a standard NexGen CR-flex prosthesis in one knee and a gender-specific NexGen CR-flex prosthesis in the other. The mean follow-up period was 3.25 years (3.1 to 3.5). The aspect ratios of the standard and gender-specific prostheses were compared with that of the distal femur.

The mean post-operative Knee Society knee scores were 94 (70 to 100) and 93 (70 to 100) points and the function scores were 83 (60 to 100) and 84 (60 to 100) points for the standard implants and the gender-specific designs, respectively. The mean post-operative Western Ontario and McMaster Universities score was 26.4 points (0 to 76). Patient satisfaction, the radiological results and the complication rates were similar in the two groups. In those with a standard prosthesis, the femoral component was closely matched in 80 knees (58.0%), overhung in 14 (10.1%) and undercovered the bone in 44 (31.9%). In those with a gender-specific prosthesis, it was closely matched in 15 knees (10.9%) and undercovered the bone in 123 (89.1%).

Since we found no significant differences between the two groups with regard to the clinical and radiological results, patient satisfaction or complication rate, the goal of the design of the gender-specific CR-flex prosthesis to improve the outcome was not achieved in our patients.

We describe the management of nonunion combined with limb-length discrepancy following vascularised fibular grafting for the reconstruction of long-bone defects in the lower limb after resection of a tumour in skeletally immature patients. We operated on nine patients with a mean age of 13.1 years (10.5 to 14.5) who presented with a mean limb-length discrepancy of 7 cm (4 to 9) and nonunion at one end of a vascularised fibular graft, which had been performed previously, to reconstruct a bone defect after resection of an osteosarcoma.

Reconstruction was carried out using a ring fixator secured with correction by half pins of any malalignment, compression of the site of nonunion and lengthening through a metaphyseal parafocal osteotomy without bone grafting. The expected limb-length discrepancy at maturity was calculated using the arithmetic method. Solid union and the intended leg length were achieved in all the patients. Excessive scarring and the distorted anatomy from previous surgery in these patients required other procedures to be performed with minimal exposures and dissection in order to avoid further compromise to the vascularity of the graft or damage to neurovascular structures. The methods which we chose were simple and effective in addressing these complex problems.

The survivorship of contemporary resurfacing arthroplasty of the hip using metal-on-metal bearings is better than that of first generation designs, but short-term failures still occur. The most common reasons for failure are fracture of the femoral neck, loosening of the component, osteonecrosis of the femoral head, reaction to metal debris and malpositioning of the component. In 2008 the Australian National Joint Registry reported an inverse relationship between the size of the head component and the risk of revision in resurfacing hip arthroplasty. Hips with a femoral component size of ≤ 44 mm have a fivefold increased risk of revision than those with femoral components of ≥ 55 mm irrespective of gender. We have reviewed the literature to explore this observation and to identify possible reasons including the design of the implant, loading of the femoral neck, the orientation of the component, the production of wear debris and the effects of metal ions, penetration of cement and vascularity of the femoral head. Our conclusion is that although multifactorial, the most important contributors to failure in resurfacing arthroplasty of the hip are likely to be the design and geometry of the component and the orientation of the acetabular component.

We present a retrospective review of a single-surgeon series of 30 consecutive lengthenings in 27 patients with congenital short femur using the Ilizarov technique performed between 1994 and 2005.

The mean increase in length was 5.8 cm/18.65% (3.3 to 10.4, 9.7% to 48.8%), with a mean time in the frame of 223 days (75 to 363). By changing from a distal to a proximal osteotomy for lengthening, the mean range of knee movement was significantly increased from 98.1° to 124.2° (p = 0.041) and there was a trend towards a reduced requirement for quadricepsplasty, although this was not statistically significant (p = 0.07). The overall incidence of regenerate deformation or fracture requiring open reduction and internal fixation was similar in the distal and proximal osteotomy groups (56.7% and 53.8%, respectively). However, in the proximal osteotomy group, pre-placement of a Rush nail reduced this rate from 100% without a nail to 0% with a nail (p < 0.001). When comparing a distal osteotomy with a proximal one over a Rush nail for lengthening, there was a significant decrease in fracture rate from 58.8% to 0% (p = 0.043).

We recommend that in this group of patients lengthening of the femur with an Ilizarov construct be carried out through a proximal osteotomy over a Rush nail. Lengthening should also be limited to a maximum of 6 cm during one treatment, or 20% of the original length of the femur, in order to reduce the risk of complications.

We have investigated the accuracy of placement of the femoral component using imageless navigation in 100 consecutive Birmingham Hip Resurfacings. Pre-operative templating determined the native neck-shaft angle and planned stem-shaft angle of the implant. The latter were verified post-operatively using digital anteroposterior unilateral radiographs of the hip.

The mean neck-shaft angle determined before operation was 132.7° (118° to 160°). The mean planned stem-shaft angle was a relative valgus alignment of 9.7° (sd 2.6). The stem-shaft angle after operation differed from that planned by a mean of 2.8° (sd 2.0) and in 86% of cases the final angle measured within ± 5° of that planned. We had no instances of notching of the neck or varus alignment of the implant in our series. A learning curve was observed in the time taken for navigation, but not for accurate placement of the implant.

Navigation in hip resurfacing may afford the surgeon a reliable and accurate method of placement of the femoral component.

Carbonate-substituted hydroxyapatite (CHA) is more osteoconductive and more resorbable than hydroxyapatite (HA), but the underlying mode of its action is unclear. We hypothesised that increased resorption of the ceramic by osteoclasts might subsequently upregulate osteoblasts by a coupling mechanism, and sought to test this in a large animal model.

Defects were created in both the lateral femoral condyles of 12 adult sheep. Six were implanted with CHA granules bilaterally, and six with HA. Six of the animals in each group received the bisphosphonate zoledronate (0.05 mg/kg), which inhibits the function of osteoclasts, intra-operatively.

After six weeks bony ingrowth was greater in the CHA implants than in HA, but not in the animals given zoledronate. Functional osteoclasts are necessary for the enhanced osteoconduction seen in CHA compared with HA.

We describe two patients aged 16 and 25 years with osteogenesis imperfecta who sustained displaced fractures of the acetabulum following minor trauma. The femoral heads were deformed by impact against the acetabular margin and both cases underwent surgical reconstruction. The quality of the bone and soft tissues made the operations challenging. There were potential complications specific to osteogenesis imperfecta, including bleeding, the creation of secondary fracture lines and shredding of the soft-tissue. The cases provide useful guidelines for addressing these difficulties.

This prospective study presents the ten-year (5 to 16) clinical and radiological results of 55 primary total hip replacements (THR) using a cementless modular femoral component (S-ROM). All patients had a significant anatomical abnormality which rendered the primary THR difficult.

The mean Harris hip score was 36 (12 to 72) pre-operatively, 83 (44 to 100) at five years, and 85 (45 to 99) at ten years. The Western Ontario and McMaster Universities osteoarthritis index (WOMAC) and short-form (SF)-12 scores were recorded from the year 2000. The mean SF-12 score at five years after surgery was 45.24 (22.74 to 56.58) for the physical component and 54.14 (29.20 to 66.61) for the mental component. By ten years the SF-12 scores were 42.86 (21.59 to 58.95) and 51.03 (33.78 to 61.40), respectively. The mean WOMAC score at five years post-operatively was 25 (0 to 59), and at ten years was 27 (2 to 70).

No femoral components were radiologically loose, although five had osteolysis in Gruen zone 1, three had osteolysis in zone 7, and two showed osteolysis in both zones 1 and 7. No osteolysis was observed around or distal to the prosthetic sleeve. No femoral components were revised, although three hips underwent an acetabular revision and two required a liner exchange. At a mean of ten years’ follow-up the S-ROM femoral component implanted for an anatomically difficult primary THR has excellent clinical and radiological results.

We have managed 27 patients (16 women and 11 men) with a mean age of 68.4 years (50 to 84), with failed total hip replacement and severe proximal femoral bone loss by revision using a distal fix/proximal wrap prosthesis. The mean follow-up was for 55.3 months (25 to 126). The mean number of previous operations was 2.2 (1 to 4). The mean Oxford hip score decreased from 46.2 (38 to 60) to 28.5 (17 to 42) (paired t-test, p < 0.001) and the mean Harris Hip score increased from 30.4 (3 to 57.7) to 71.7 (44 to 99.7) (paired t-test, p < 0.001). There were two dislocations, and in three patients we failed to eradicate previous infection. None required revision of the femoral stem.

This technique allows instant distal fixation while promoting biological integration and restoration of bone stock. In the short term, the functional outcome is encouraging and the complication rates acceptable in this difficult group of patients.

Conventional treatment of mild slipped capital femoral epiphysis consists of fixation in situ with wires or screws. Recent contributions to the literature suggest that even a mild slip may lead to early damage of the acetabular labrum and adjacent cartilage by abutment of a prominent femoral metaphysis. It has been suggested that the appropriate treatment in mild slipped capital femoral epiphysis should not only prevent further slipping of the epiphysis, but also address potential femoroacetabular impingement by restoring the anatomy of the proximal femur.

Between October 1984 and December 1995 we treated 16 patients for unilateral mild slipped capital femoral epiphysis by fixation in situ with Kirschner wires. In this study we have reviewed these patients for clinical and radiological evidence of femoroacetabular impingement. There was little clinical indication of impingement but radiological evaluation assessing the femoral head-neck ratio and measuring the Nötzli α angle on the anteroposterior and cross-table radiographs showed significant alterations in the proximal femur. None of the affected hips had a normal head-neck ratio and the mean α angle was 86° (55° to 99°) and 55° (40° to 94°) on the anteroposterior and lateral cross-table radiographs, respectively.

While our clinical data favours conventional treatment, our radiological findings are in support of restoring the anatomy of the proximal femur to avoid or delay the development of femoroacetabular impingement following mild slipped capital femoral epiphysis.

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.

A clinical and radiological study was conducted on 97 total hip replacements performed for congenital hip dislocation in 79 patients between 1989 and 1998 using a three-dimensional custom-made cementless stem. The mean age at operation was 48 years (17 to 72) and the mean follow-up was for 123 months (83 to 182).

According to the Crowe classification, there were 37 class I, 28 class II, 13 class III and 19 class IV hips. The mean leg lengthening was 25 mm (5 to 58), the mean pre-operative femoral anteversion was 38.6° (2° to 86°) and the mean correction in the prosthetic neck was −23.6° (−71° to 13°). The mean Harris hip score improved from 58 (15 to 84) to 93 (40 to 100) points. A revision was required in six hips (6.2%). The overall survival rate was 89.5% (95% confidence interval 89.2 to 89.8) at 13 years when two hips were at risk.

This custom-made cementless femoral component, which can be accommodated in the abnormal proximal femur and will correct the anteversion and frontal offset, provided good results without recourse to proximal femoral corrective osteotomy.

Systemic mastocytosis is a rare condition that often involves the bone marrow. We report the case of a patient with systemic mastocytosis who underwent total hip replacement. Technical difficulties encountered during the procedure included a narrow medullary canal and abnormally hard bone, later confirmed by laboratory measurements. Follow-up at five years showed a good clinical and radiological outcome.

A giant cell tumour is a primary lesion of bone of intermediate severity. Its histogenesis is unclear. In a few cases pulmonary metastases have been described. Multiple skeletal metastases in the absence of sarcomatous change have been observed.

We present a case report of a 25-year-old woman with a recurrent giant cell tumour of the distal fibula. After a second recurrence and six years after the initial diagnosis, she rapidly developed multiple bony metastases. The outcome was fatal.

This paper summarises the current knowledge on the effects of medullary reaming of long-bone fractures. Following a review of intramedullary vascular physiology, the consequences for vascularity, the autograft effects, the generation of heat, and fat embolism are outlined. Also, alternative reaming techniques are described.