This multicentre study analysed 12 alumina ceramic-on-ceramic components retrieved from squeaking total hip replacements after a mean of 23 months in situ (11 to 61). The rates and patterns of wear seen in these squeaking hips were compared with those seen in matched controls using retrieval data from 33 ‘silent’ hip replacements with similar ceramic bearings. All 12 bearings showed evidence characteristic of edge-loading wear. The median rate of volumetric wear was 3.4 mm³/year for the acetabular component, 2.9 mm³/year on the femoral heads and 6.3 mm³/year for head and insert combined. This was up to 45 times greater than that of previously reported silent ceramic-on-ceramic retrievals. The rate of wear seen in ceramic components revised for squeaking hips appears to be much greater than in that seen in retrievals from ‘silent’ hips.

Objectives

We aimed to further evaluate the biomechanical characteristics of two locking screws versus three standard bicortical screws in synthetic models of normal and osteoporotic bone.

We evaluated the biomechanical properties of two different methods of fixation for unstable fractures of the proximal humerus. Biomechanical testing of the two groups, locking plate alone (LP), and locking plate with a fibular strut graft (LPSG), was performed using seven pairs of human cadaveric humeri. Cyclical loads between 10 N and 80 N at 5 Hz were applied for 1 000 000 cycles. Immediately after cycling, an increasing axial load was applied at a rate of displacement of 5 mm/min. The displacement of the construct, maximum failure load, stiffness and mode of failure were compared.

The displacement was significantly less in the LPSG group than in the LP group (p = 0.031). All maximum failure loads and measures of stiffness in the LPSG group were significantly higher than those in the LP group (p = 0.024 and p = 0.035, respectively). In the LP group, varus collapse and plate bending were seen. In the LPSG group, the humeral head cut out and the fibular strut grafts fractured. No broken plates or screws were seen in either group.

We conclude that strut graft augmentation significantly increases both the maximum failure load and the initial stiffness of this construct compared with a locking plate alone.

We report the outcome of 32 patients (37 knees) who underwent hemicallostasis with a dynamic external fixator for osteoarthritis of the medial compartment of the knee. There were 16 men (19 knees) and 16 women (18 knees) with a mean age at operation of 54.6 years (27 to 72). The aim was to achieve a valgus overcorrection of 2° to 8° or mechanical axis at 62.5% (± 12.5%). At a mean follow-up of 62.8 months (51 to 81) there was no change in the mean range of movement, and no statistically significant difference in the Insall-Salvati index or tibial slope (p = 0.11 and p = 0.15, respectively). The mean hip-knee-ankle angle changed from 190.6 (183° to 197°) to 176.0° (171° to 181°), with a mean final position of the mechanical axis of 58.5% (35.1% to 71.2%).

The desired alignment was attained in 31 of 37 (84%) knees. There were 21 excellent, 13 good, two fair and one poor result according to the Oxford knee score with no correlation between age and final score. This score was at its best at one year with a statistically significant deterioration at two years (p = 0.001) followed by a small but not statistically significant deterioration until the final follow-up (p = 0.17). All the knees with Ahlback grade 1 osteoarthritis had excellent or good results. Complications included pin tract infections involving 16.4% of all pins used, delayed union in two, knee stiffness in four, fracture of the lateral cortex in one and ring sequestrum in one.

In conclusion, hemicallostasis provides precision in attaining the desired alignment without interfering with tibial slope or patellar height, and is relatively free of serious complications.

Failure of bone repair is a challenging problem in the management of fractures. There is a limited supply of autologous bone grafts for treating nonunions, with associated morbidity after harvesting. There is need for a better source of cells for repair. Mesenchymal stem cells (MSCs) hold promise for healing of bone because of their capacity to differentiate into osteoblasts and their availability from a wide variety of sources. Our review aims to evaluate the available clinical evidence and recent progress in strategies which attempt to use autologous and heterologous MSCs in clinical practice, including genetically-modified MSCs and those grown on scaffolds. We have compared various procedures for isolating and expanding a sufficient number of MSCs for use in a clinical setting.

There are now a number of clinical studies which have shown that implantation of MSCs is an effective, safe and durable method for aiding the repair and regeneration of bone.

Patella subluxation assessed on dynamic MRI has previously been shown to be associated with anterior knee pain. In this MRI study of 60 patients we investigated the relationship between subluxation and multiple bony, cartilaginous and soft-tissue factors that might predispose to subluxation using discriminant function analysis.

Patella engagement (% of patella cartilage overlapping with trochlea cartilage) had the strongest relationship with subluxation. Patellae with > 30% engagement tended not to sublux; those with < 30% tended to sublux. Other factors that were associated with subluxation included the tibial tubercle-trochlea notch distance, vastus medialis obliquus distance from patella, patella alta, and the bony and cartilaginous sulcus angles in the superior part of the trochlea. No relationship was found between subluxation and sulcus angles for cartilage and bone in the middle and lower part of the trochlea, cartilage thicknesses and Wiberg classification of the patella.

This study indicates that patella engagement is a key factor associated with patellar subluxation. This suggests that in patients with anterior knee pain with subluxation, resistant to conservative management, surgery directed towards improving patella engagement should be considered. A clinical trial is necessary to test this hypothesis.

We describe a retrospective review of 38 cases of reconstruction following resection of the metaphysiodiaphysis of the lower limb for malignant bone tumours using free vascularised fibular grafts. The mean follow-up was for 7.6 years (0.4 to 18.4). The mean Musculoskeletal Tumor Society score was 27.2 (20 to 30). The score was significantly higher when the graft was carried out in a one-stage procedure after resection of the tumour rather than in two stages. Bony union was achieved in 89% of the cases. The overall mean time to union was 1.7 years (0.2 to 10.3).

Free vascularised fibular transfer is a major operation with frequent, but preventable, complications which allows salvage of the limb with satisfactory functional results.

Percutaneous stabilisation of tibial fractures by locking plates has become an accepted form of osteosynthesis. A potential disadvantage of this technique is the risk of damage to the neurovascular bundles in the anterior and peroneal compartments. Our aim in this anatomical study was to examine the relationship of the deep peroneal nerve to a percutaneously-inserted Less Invasive Stabilisation System tibial plate in the lower limbs of 18 cadavers. Screws were inserted through stab incisions. The neurovascular bundle was dissected to reveal its relationship to the plate and screws.

In all cases, the deep peroneal nerve was in direct contact with the plate between the 11th and the 13th holes. In ten specimens the nerve crossed superficial to the plate, in six it was interposed between the plate and the bone and in the remaining two specimens it coursed at the edge of the plate.

Percutaneous insertion of plates with more than ten holes is not recommended because of the risk of injury to the neurovascular structures. When longer plates are required we suggest distal exposure so that the neurovascular bundle may be displayed and protected.

We present two children with massive defects of the tibia and an associated active infection who were treated by medial transport of the fibula using the Ilizarov device. The first child had chronic discharging osteomyelitis which affected the whole tibial shaft. The second had sustained bilateral grade-IIIB open tibial fractures in a motor-car accident. The first child was followed up for three years and the second for two years. Both achieved solid union between the proximal and distal stumps of the tibia and the fibula, with hypertrophy of the fibula. The first child had a normal range of movement at the knee, ankle and foot but there was shortening of 1.5 cm. The second had persistent anterior angulation at the proximal tibiofibular junction and the ankle was stiff in equinus.

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.

Ten patients, who were unsuitable for limb lengthening over an intramedullary nail, underwent lengthening with a submuscular locking plate. Their mean age at operation was 18.5 years (11 to 40). After fixing a locking plate submuscularly on the proximal segment, an external fixator was applied to lengthen the bone after corticotomy. Lengthening was at 1 mm/day and on reaching the target length, three or four screws were placed in the plate in the distal segment and the external fixator was removed. All patients achieved the pre-operative target length at a mean of 4.0 cm (3.2 to 5.5). The mean duration of external fixation was 61.6 days (45 to 113) and the mean external fixation index was 15.1 days/cm (13.2 to 20.5), which was less than one-third of the mean healing index (48 days/cm (41.3 to 55). There were only minor complications.

Lengthening with a submuscular locking plate can successfully permit early removal of the fixator with fewer complications and is a useful alternative in children or when nailing is difficult.

The cause of fracture of the femoral neck after hip resurfacing is poorly understood. In order to evaluate the role of avascular necrosis we compared 19 femoral heads retrieved at revision for fracture of the femoral neck and 13 retrieved for other reasons.

We developed a new technique of assessing avascular necrosis in the femoral head by determining the percentage of empty osteocyte lacunae present. Femoral heads retrieved as controls at total hip replacement for osteoarthritis and avascular necrosis had 9% (sd 4; n = 13) and 85% (sd 5; n = 10, p < 0.001) empty lacunae, respectively.

In the fracture group the percentage of empty lacunae was 71% (sd 22); in the other group it was 21% (sd 13). The differences between the groups were highly significant (p < 0.001).

We conclude that fracture after resurfacing of the hip is associated with a significantly greater percentage of empty osteocyte lacunae within the trabecular bone. This indicates established avascular necrosis and suggests that damage to the blood supply at the time of surgery is a potent risk factor for fracture of the femoral neck after hip resurfacing.

Conventional non-steroidal anti-inflammatory drugs (NSAIDs) and newer specific cyclo-oxygenase-2 (cox-2) inhibitors are commonly used in musculoskeletal trauma and orthopaedic surgery to reduce the inflammatory response and pain. These drugs have been reported to impair bone metabolism. In reconstruction of the anterior cruciate ligament the hamstring tendons are mainly used as the graft of choice, and a prerequisite for good results is healing of the tendons in the bone tunnel. Many of these patients are routinely given NSAIDs or cox-2 inhibitors, although no studies have elucidated the effects of these drugs on tendon healing in the bone tunnel.

In our study 60 female Wistar rats were randomly allocated into three groups of 20. One received parecoxib, one indometacin and one acted as a control. In all the rats the tendo-Achillis was released proximally from the calf muscles. It was then pulled through a drill hole in the distal tibia and sutured anteriorly. The rats were given parecoxib, indometacin or saline intraperitoneally twice daily for seven days. After 14 days the tendon/bone-tunnel interface was subjected to mechanical testing.

Significantly lower maximum pull-out strength (p < 0.001), energy absorption (p < 0.001) and stiffness (p = 0.035) were found in rats given parecoxib and indometacin compared with the control group, most pronounced with parecoxib.

Soaking bone grafts in a bisphosphonate solution before implantation can prevent their resorption and increase the local bone density in rats and humans. However, recent studies suggest that pre-treatment of allografts with bisphosphonate can prevent bone ingrowth into impaction grafts. We tested the hypothesis that excessive amounts of bisphosphonate would also cause a negative response in less dense grafts. We used a model where non-impacted metaphyseal bone grafts were randomised into three groups with either no bisphosphonate, alendronate followed by rinsing, and alendronate without subsequent rinsing, and inserted into bone chambers in rats. The specimens were evaluated histologically at one week, and by histomorphometry and radiology at four weeks. At four weeks, both bisphosphonate groups showed an increase in the total bone content, increased newly formed bone, and higher radiodensity than the controls. In spite of being implanted in a chamber with a limited opportunity to diffuse, even an excessive amount of bisphosphonate improved the outcome. We suggest that the negative results seen by others could be due to the combination of densely compacted bone and a bisphosphonate.

We suggest that bisphosphonates are likely to have a negative influence where resorption is a prerequisite to create space for new bone ingrowth.

Between June 1999 and May 2003 we undertook direct primary closure of the skin wounds of 173 patients with Gustilo and Anderson grade-IIIA and grade-IIIB open fractures. These patients were selected from a consecutive group of 557 with type-III injuries presenting during this time. Strict criteria for inclusion in the study included debridement within 12 hours of injury, no sewage or organic contamination, no skin loss either primarily or secondarily during debridement, a Ganga Hospital open injury skin score of 1 or 2 with a total score of ten or less, the presence of bleeding skin margins, the ability to approximate wound edges without tension and the absence of peripheral vascular disease. In addition, patients with polytrauma were excluded.

At a mean follow-up of 6.2 years (5 to 7), the outcome was excellent in 150 (86.7%), good in 11 (6.4%) and poor in 12 (6.9%). A total of 33 complications occurred in 23 patients including superficial infection in 11, deep infection in five and the requirement for a secondary skin flap in three. Six patients developed nonunion requiring further surgery, one of whom declined additional measures to treat an established infected nonunion.

Immediate skin closure when performed selectively with the above indications proved to be a safe procedure.

The rotational alignment of the tibia is an unresolved issue in knee replacement. A poor functional outcome may be due to malrotation of the tibial component. Our aim was to find a reliable method for positioning the tibial component in knee replacement.

CT scans of 19 knees were reconstructed in three dimensions and orientated vertically. An axial plane was identified 20 mm below the tibial spines. The centre of each tibial condyle was calculated from ten points taken round the condylar cortex. The tibial tubercle centre was also generated as the centre of the circle which best fitted eight points on the outside of the tubercle in an axial plane at the level of its most prominent point.

The derived points were identified by three observers with errors of 0.6 mm to 1 mm. The medial and lateral tibial centres were constant features (radius 24 mm (sd 3), and 22 mm (sd 3), respectively). An anatomical axis was created perpendicular to the line joining these two points. The tubercle centre was found to be 20 mm (sd 7) lateral to the centre of the medial tibial condyle. Compared with this axis, an axis perpendicular to the posterior condylar axis was internally rotated by 6° (sd 3). An axis based on the tibial tubercle and the tibial spines was also internally rotated by 5° (sd 10).

Alignment of the knee when based on this anatomical axis was more reliable than either the posterior surfaces or any axis involving the tubercle which was the least reliable landmark in the region.

Post-natal vasculogenesis, the process by which vascular committed bone marrow stem cells or endothelial precursor cells migrate, differentiate and incorporate into the nacent endothelium and thereby contribute to physiological and pathological neurovascularisation, has stimulated much interest. Its contribution to neovascularisation of tumours, wound healing and revascularisation associated with ischaemia of skeletal and cardiac muscles is well established. We evaluated the responses of endothelial precursor cells in bone marrow to musculoskeletal trauma in mice.

Bone marrow from six C57 Black 6 mice subjected to a standardised, closed fracture of the femur, was analysed for the combined expression of cell-surface markers stem cell antigen 1 (sca-1⁺) and stem cell factor receptor, CD117 (c-kit⁺) in order to identify the endothelial precursor cell population. Immunomagnetically-enriched sca-1⁺ mononuclear cell (MNC^sca-1+) populations were then cultured and examined for functional vascular endothelial differentiation. Bone marrow MNC^{sca-1+,c-kit+} counts increased almost twofold within 48 hours of the event, compared with baseline levels, before decreasing by 72 hours.

Sca-1⁺ mononuclear cell populations in culture from samples of bone marrow at 48 hours bound together Ulex Europus-1, and incorporated fluorescent 1,1′-dioctadecyl- 3,3,3,’3′-tetramethylindocarbocyanine perchlorate-labelled acetylated low-density lipoprotein intracellularily, both characteristics of mature endothelium.

Our findings suggest that a systemic provascular response of bone marrow is initiated by musculoskeletal trauma. Its therapeutic manipulation may have implications for the potential enhancement of neovascularisation and the healing of fractures.

Surgeons need to be able to measure angles and distances in three dimensions in the planning and assessment of knee replacement. Computed tomography (CT) offers the accuracy needed but involves greater radiation exposure to patients than traditional long-leg standing radiographs, which give very little information outside the plane of the image.

There is considerable variation in CT radiation doses between research centres, scanning protocols and individual scanners, and ethics committees are rightly demanding more consistency in this area.

By refining the CT scanning protocol we have reduced the effective radiation dose received by the patient down to the equivalent of one long-leg standing radiograph. Because of this, it will be more acceptable to obtain the three-dimensional data set produced by CT scanning. Surgeons will be able to document the impact of implant position on outcome with greater precision.

Achieving deep flexion after total knee replacement remains a challenge. In this study we compared the soft-tissue tension and tibiofemoral force in a mobile-bearing posterior cruciate ligament-sacrificing total knee replacement, using equal flexion and extension gaps, and with the gaps increased by 2 mm each. The tests were conducted during passive movement in five cadaver knees, and measurements of strain were made simultaneously in the collateral ligaments. The tibiofemoral force was measured using a customised mini-force plate in the tibial tray. Measurements of collateral ligament strain were not very sensitive to changes in the gap ratio, but tibiofemoral force measurements were. Tibiofemoral force was decreased by a mean of 40% (sd 10.7) after 90° of knee flexion when the flexion gap was increased by 2 mm. Increasing the extension gap by 2 mm affected the force only in full extension. Because increasing the range of flexion after total knee replacement beyond 110° is a widely-held goal, small increases in the flexion gap warrant further investigation.

We investigated several factors which affect the stability of cortical screws in osteoporotic bone using 18 femora from cadavers of women aged between 45 and 96 years (mean 76). We performed bone densitometry to measure the bone mineral density of the cortical and cancellous bone of the shaft and head of the femur, respectively. The thickness and overall bone mass of the cortical layer of the shaft of the femur were measured using a microCT scanner. The force required to pull-out a 3.5 mm titanium cortical bone screw was determined after standardised insertion into specimens of the cortex of the femoral shaft.

A significant correlation was found between the pull-out strength and the overall bone mass of the cortical layer (r² = 0.867, p < 0.01) and also between its thickness (r² = 0.826, p < 0.01) and bone mineral density (r² = 0.861, p < 0.01). There was no statistically significant correlation between the age of the donor and the pull-out force (p = 0.246), the cortical thickness (p = 0.199), the bone mineral density (p = 0.697) or the level of osteoporosis (p = 0.378).

We conclude that the overall bone mass, the thickness and the bone mineral density of the cortical layer, are the main factors which affect the stability of a screw in human female osteoporotic cortical bone.