Hip simulators have been used for ten years to determine the tribological performance of large-head metal-on-metal devices using traditional test conditions. However, the hip simulator protocols were originally developed to test metal-on-polyethylene devices. We have used patient activity data to develop a more physiologically relevant test protocol for metal-on-metal devices. This includes stop/start motion, a more appropriate walking frequency, and alternating kinetic and kinematic profiles.

There has been considerable discussion about the effect of heat treatments on the wear of metal-on-metal cobalt chromium molybdenum (CoCrMo) devices. Clinical studies have shown a higher rate of wear, levels of metal ions and rates of failure for the heat-treated metal compared to the as-cast metal CoCrMo devices. However, hip simulator studies in vitro under traditional testing conditions have thus far not been able to demonstrate a difference between the wear performance of these implants.

Using a physiologically relevant test protocol, we have shown that heat treatment of metal-on-metal CoCrMo devices adversely affects their wear performance and generates significantly higher wear rates and levels of metal ions than in as-cast metal implants.

Aims

The surgical management of ankle arthritis with tibiotalar arthrodesis is known to alter gait, as compared with normal ankles. The purpose of this study was to assess post-operative gait function with gait before arthrodesis.

Objectives

The objective of this study was to compare the elution characteristics, antimicrobial activity and mechanical properties of antibiotic-loaded bone cement (ALBC) loaded with powdered antibiotic, powdered antibiotic with inert filler (xylitol), or liquid antibiotic, particularly focusing on vancomycin and amphotericin B.

Objectives

We sought to determine if a durable bilayer implant composed of trabecular metal with autologous periosteum on top would be suitable to reconstitute large osteochondral defects. This design would allow for secure implant fixation, subsequent integration and remodeling.

Cartilage repair in terms of replacement, or regeneration of damaged or diseased articular cartilage with functional tissue, is the ‘holy grail’ of joint surgery. A wide spectrum of strategies for cartilage repair currently exists and several of these techniques have been reported to be associated with successful clinical outcomes for appropriately selected indications. However, based on respective advantages, disadvantages, and limitations, no single strategy, or even combination of strategies, provides surgeons with viable options for attaining successful long-term outcomes in the majority of patients. As such, development of novel techniques and optimisation of current techniques need to be, and are, the focus of a great deal of research from the basic science level to clinical trials. Translational research that bridges scientific discoveries to clinical application involves the use of animal models in order to assess safety and efficacy for regulatory approval for human use. This review article provides an overview of animal models for cartilage repair.

Cite this article: Bone Joint Res 2014;4:89–94.

Although equinus gait is the most common abnormality in children with spastic cerebral palsy (CP) there is no consistency in recommendations for treatment, and evidence for best practice is lacking. The Baumann procedure allows selective fractional lengthening of the gastrocnemii and soleus muscles but the long-term outcome is not known. We followed a group of 18 children (21 limbs) with diplegic CP for ten years using three-dimensional instrumented gait analysis. The kinematic parameters of the ankle joint improved significantly following this procedure and were maintained until the end of follow-up. We observed a normalisation of the timing of the key kinematic and kinetic parameters, and an increase in the maximum generation of power of the ankle. There was a low rate of overcorrection (9.5%, n = 2), and a rate of recurrent equinus similar to that found with other techniques (23.8%, n = 5).

As the procedure does not impair the muscle architecture, and allows for selective correction of the contracted gastrocnemii and soleus, it may be recommended as the preferred method for correction of a mild fixed equinus deformity.

In arthritis of the varus knee, a high tibial osteotomy (HTO) redistributes load from the diseased medial compartment to the unaffected lateral compartment.

We report the outcome of 36 patients (33 men and three women) with 42 varus, arthritic knees who underwent HTO and dynamic correction using a Garches external fixator until they felt that normal alignment had been restored. The mean age of the patients was 54.11 years (34 to 68). Normal alignment was achieved at a mean 5.5 weeks (3 to 10) post-operatively. Radiographs, gait analysis and visual analogue scores for pain were measured pre- and post-operatively, at one year and at medium-term follow-up (mean six years; 2 to 10). Failure was defined as conversion to knee arthroplasty.

Pre-operative gait analysis divided the 42 knees into two equal groups with high (17 patients) or low (19 patients) adductor moments. After correction, a statistically significant (p < 0.001, t-test,) change in adductor moment was achieved and maintained in both groups, with a rate of failure of three knees (7.1%), and 89% (95% confidence interval (CI) 84.9 to 94.7) survivorship at medium-term follow-up.

At final follow-up, after a mean of 15.9 years (12 to 20), there was a survivorship of 59% (95% CI 59.6 to 68.9) irrespective of adductor moment group, with a mean time to conversion to knee arthroplasty of 9.5 years (3 to 18; 95% confidence interval ± 2.5).

HTO remains a useful option in the medium-term for the treatment of medial compartment osteoarthritis of the knee but does not last in the long-term.

Cite this article: Bone Joint J 2016;98-B:601–7.

Objectives

Hips with metal-on-metal total hip arthroplasty (MoM THA) have a high rate of adverse local tissue reactions (ALTR), often associated with hypersensitivity reactions. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) measures tissue perfusion with the parameter Ktrans (volume transfer constant of contrast agent). Our purpose was 1) to evaluate the feasibility of DCE-MRI in patients with THA and 2) to compare DCE-MRI in patients with MoM bearings with metal-on-polyethylene (MoP) bearings, hypothesising that the perfusion index Ktrans in hips with MoM THA is higher than in hips with MoP THA.

Determining and accurately restoring the flexion-extension axis of the elbow is essential for functional recovery after total elbow arthroplasty (TEA). We evaluated the effect of morphological features of the elbow on variations of alignment of the components at TEA. Morphological and positioning variables were compared by systematic CT scans of 22 elbows in 21 patients after TEA.

There were five men and 16 women, and the mean age was 63 years (38 to 80). The mean follow-up was 22 months (11 to 44).

The anterior offset and version of the humeral components were significantly affected by the anterior angulation of the humerus (p = 0.052 and p = 0.004, respectively). The anterior offset and version of the ulnar components were strongly significantly affected by the anterior angulation of the ulna (p < 0.001 and p < 0.001).

The closer the anterior angulation of the ulna was to the joint, the lower the ulnar anterior offset (p = 0.030) and version of the ulnar component (p = 0.010). The distance from the joint to the varus angulation also affected the lateral offset of the ulnar component (p = 0.046).

Anatomical variations at the distal humerus and proximal ulna affect the alignment of the components at TEA. This is explained by abutment of the stems of the components and is particularly severe when there are substantial deformities or the deformities are close to the joint.

Cite this article: Bone Joint J 2015;97-B:1539–45.

It has been suggested that extracorporeal shockwave therapy is a safe and effective treatment for pain relief from recalcitrant plantar fasciopathy (PF). However, the changes in gait and associated biomechanical parameters have not been well characterised. We recruited 12 female patients with recalcitrant PF who had a mean age of 59 years (50 to 70) and mean body mass index of 25 kg/m² (22 to 30). The patients reported a mean duration of symptoms of 9.3 months (6 to 15). Shockwave therapy consisting of 1500 impulses (energy flux density 0.26 mJ/mm²) was applied for three sessions, each three weeks apart. A pain visual analogue scale (VAS) rating, plantar pressure assessment and motion analysis were carried out before and nine weeks after first shock wave therapy. It was demonstrated that patients increased their walking velocity and cadence as well indicating a decrease in pain after shockwave therapy. In the symptomatic foot, the peak contact pressure over the forefoot increased and the contact area over the digits decreased. The total foot impulse also decreased as did stance duration. The duration the centre of pressure remained in the hindfoot increased in the symptomatic foot after shockwave therapy. The differences in centre of pressure trajectory at baseline decreased at final follow-up. In conclusion, shockwave therapy not only decreased the pain VAS rating but also improved the gait parameters of the symptomatic foot in PF patients.

Cite this article: Bone Joint J 2013;95-B:1088–93.

Hallux rigidus was first described in 1887. Many aetiological factors have been postulated, but none has been supported by scientific evidence. We have examined the static and dynamic imbalances in the first metatarsophalangeal joint which we postulated could be the cause of this condition. We performed a finite-element analysis study on a male subject and calculated a mathematical model of the joint when subjected to both normal and abnormal physiological loads.

The results gave statistically significant evidence for an increase in tension of the plantar fascia as the cause of abnormal stress on the articular cartilage rather than mismatch of the articular surfaces or subclinical muscle contractures. Our study indicated a clinical potential cause of hallux rigidus and challenged the many aetiological theories. It could influence the choice of surgical procedure for the treatment of early grades of hallux rigidus.

Infection of a total hip replacement (THR) requires component removal and thorough local debridement. Usually, long-term antibiotic treatment in conjunction with a two-stage revision is required. This may take several months. One-stage revision using antibiotic-loaded cement has not gained widespread use, although the clinical and economic advantages are obvious. Allograft bone may be impregnated with high levels of antibiotics, and in revision of infected THR, act as a carrier providing a sustained high local concentration.

We performed 37 one-stage revision of infected THRs, without the use of cement. There were three hips which required further revision because of recurrent infection, the remaining 34 hips (92%) stayed free from infection and stable at a mean follow-up of 4.4 years (2 to 8). No adverse effects were identified. Incorporation of bone graft was comparable with unimpregnated grafts.

Antibiotic-impregnated allograft bone may enable reconstruction of bone stock, insertion of an uncemented implant and control of infection in a single operation in revision THR for infection.

Tendinopathy is a debilitating musculoskeletal condition which can cause significant pain and lead to complete rupture of the tendon, which often requires surgical repair. Due in part to the large spectrum of tendon pathologies, these disorders continue to be a clinical challenge. Animal models are often used in this field of research as they offer an attractive framework to examine the cascade of processes that occur throughout both tendon pathology and repair. This review discusses the structural, mechanical, and biological changes that occur throughout tendon pathology in animal models, as well as strategies for the improvement of tendon healing.

Cite this article: Bone Joint Res 2014;3:193–202.

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.

Injury to the anterior cruciate ligament (ACL) is one of the most devastating and frequent injuries of the knee. Surgical reconstruction is the current standard of care for treatment of ACL injuries in active patients. The widespread adoption of ACL reconstruction over primary repair was based on early perception of the limited healing capacity of the ACL. Although the majority of ACL reconstruction surgeries successfully restore gross joint stability, post-traumatic osteoarthritis is commonplace following these injuries, even with ACL reconstruction. The development of new techniques to limit the long-term clinical sequelae associated with ACL reconstruction has been the main focus of research over the past decades. The improved knowledge of healing, along with recent advances in tissue engineering and regenerative medicine, has resulted in the discovery of novel biologically augmented ACL-repair techniques that have satisfactory outcomes in preclinical studies. This instructional review provides a summary of the latest advances made in ACL repair.

Cite this article: Bone Joint Res 2014;3:20–31.

Articular cartilage repair remains a challenge to surgeons and basic scientists. The field of tissue engineering allows the simultaneous use of material scaffolds, cells and signalling molecules to attempt to modulate the regenerative tissue. This review summarises the research that has been undertaken to date using this approach, with a particular emphasis on those techniques that have been introduced into clinical practice, via in vitro and preclinical studies.

The April 2012 Research Roundup³⁶⁰ looks at who is capable of being an arthroscopist, bupivacaine, triamcinolone and chondrotoxicity, reducing scarring in injured skeletal muscle, horny Goat Weed and the repair of osseous defects, platelet-derived growth factor and fracture healing, the importance of the reserve zone in a child’s growth plate, coping with advanced arthritis, hydroxyapatite and platelet-rich plasma for bone defects, and calcium phosphate and bone regeneration

In a double-blinded randomised controlled trial, 83 patients with primary osteoarthritis of the hip received either a ceramic-on-metal (CoM) or metal-on-metal (MoM) total hip replacement (THR). The implants differed only in the bearing surfaces used. The serum levels of cobalt and chromium and functional outcome scores were compared pre-operatively and at six and 12 months post-operatively.

Data were available for 41 CoM and 36 MoM THRs (four patients were lost to follow-up, two received incorrect implants). The baseline characteristics of both cohorts were similar. Femoral head size measured 36 mm in all but two patients who had 28 mm heads. The mean serum cobalt and chromium levels increased in both groups, with no difference noted between groups at six months (cobalt p = 0.67, chromium p = 0.87) and 12 months (cobalt p = 0.76, chromium p = 0.76) post-operatively. Similarly, the mean Oxford hip scores, Western Ontario and McMaster Universities Osteoarthritis index and University of California, Los Angeles activity scores showed comparable improvement at 12 months.

Our findings indicate that CoM and MoM couplings are associated with an equivalent increase in serum cobalt and chromium levels, and comparable functional outcome scores at six and 12-months follow-up.

Scapulothoracic fusion (STF) for painful winging of the scapula in neuromuscular disorders can provide effective pain relief and functional improvement, but there is little information comparing outcomes between patients with dystrophic and non-dystrophic conditions. We performed a retrospective review of 42 STFs in 34 patients with dystrophic and non-dystrophic conditions using a multifilament trans-scapular, subcostal cable technique supported by a dorsal one-third semi-tubular plate. There were 16 males and 18 females with a mean age of 30 years (15 to 75) and a mean follow-up of 5.0 years (2.0 to 10.6). The mean Oxford shoulder score improved from 20 (4 to 39) to 31 (4 to 48). Patients with non-dystrophic conditions had lower overall functional scores but achieved greater improvements following STF. The mean active forward elevation increased from 59° (20° to 90°) to 97° (30° to 150°), and abduction from 51° (10° to 90°) to 83° (30° to 130°) with a greater range of movement achieved in the dystrophic group. Revision fusion for nonunion was undertaken in five patients at a mean time of 17 months (7 to 31) and two required revision for fracture. There were three pneumothoraces, two rib fractures, three pleural effusions and six nonunions. The main risk factors for nonunion were smoking, age and previous shoulder girdle surgery.

STF is a salvage procedure that can provide good patient satisfaction in 82% of patients with both dystrophic and non-dystrophic pathologies, but there was a relatively high failure rate (26%) when poor outcomes were analysed. Overall function was better in patients with dystrophic conditions which correlated with better range of movement; however, patients with non-dystrophic conditions achieved greater functional improvement.