We report the effects of local administration of osteogenic protein-1 on the biomechanical properties of the overstretched anterior cruciate ligament in an animal model. An injury in the anterior cruciate ligament was created in 45 rabbits. They were divided into three equal groups. In group 1, no treatment was applied, in group II, phosphate-buffered saline was applied around the injured ligament, and in group III, 12.5 μg of osteogenic protein-1 mixed with phosphate-buffered saline was applied around the injured ligament. A control group of 15 rabbits was assembled from randomly-selected injured knees from among the first three groups. Each rabbit was killed at 12 weeks.

The maximum load and stiffness of the anterior cruciate ligament was found to be significantly greater in group III than either group 1 (p = 0.002, p = 0.014) or group II (p = 0.032, p = 0.025). The tensile strength and the tangent modulus of fascicles from the ligament were also significantly greater in group III than either group I (p = 0.002, p = 0.0174) or II (p = 0.005, p = 0.022).

The application of osteogenic protein-1 enhanced the healing in the injured anterior cruciate ligament, but compared with the control group the treated ligament remained lengthened. The administration of osteogenic protein-1 may have a therapeutic role in treating the overstretched anterior cruciate ligament.

Matrix metalloproteinases (MMPs), responsible for extracellular matrix remodelling and angiogenesis, might play a major role in the response of the growth plate to detrimental loads that lead to overuse injuries in young athletes. In order to test this hypothesis, human growth plate chondrocytes were subjected to mechanical forces equal to either physiological loads, near detrimental or detrimental loads for two hours. In addition, these cells were exposed to physiological loads for up to 24 hours. Changes in the expression of MMPs -2, -3 and -13 were investigated.

We found that expression of MMPs in cultured human growth plate chondrocytes increases in a linear manner with increased duration and intensity of loading. We also showed for the first time that physiological loads have the same effect on growth plate chondrocytes over a long period of time as detrimental loads applied for a short period.

These findings confirm the involvement of MMPs in overuse injuries in children. We suggest that training programmes for immature athletes should be reconsidered in order to avoid detrimental stresses and over-expression of MMPs in the growth plate, and especially to avoid physiological loads becoming detrimental.

Cite this article: Bone Joint J 2013;95-B:568–73.

Mesenchymal stem-cell based therapies have been proposed as novel treatments for intervertebral disc degeneration, a prevalent and disabling condition associated with back pain. The development of these treatment strategies, however, has been hindered by the incomplete understanding of the human nucleus pulposus phenotype and by an inaccurate interpretation and translation of animal to human research. This review summarises recent work characterising the nucleus pulposus phenotype in different animal models and in humans and integrates their findings with the anatomical and physiological differences between these species. Understanding this phenotype is paramount to guarantee that implanted cells restore the native functions of the intervertebral disc.

Cite this article: Bone Joint Res 2013;2:169–78.

Objectives

This study aimed to investigate time-dependent gene expression of injured human anterior cruciate ligament (ACL), and to evaluate the histological changes of the ACL remnant in terms of cellular characterisation.

The role of inflammatory cells and their products in tendinopathy is not completely understood. Pro-inflammatory cytokines are upregulated after oxidative and other forms of stress. Based on observations that increased cytokine expression has been demonstrated in cyclically-loaded tendon cells we hypothesised that because of their role in oxidative stress and apoptosis, pro-inflammatory cytokines may be present in rodent and human models of tendinopathy. A rat supraspinatus tendinopathy model produced by running overuse was investigated at the genetic level by custom micro-arrays. Additionally, samples of torn supraspinatus tendon and matched intact subscapularis tendon were collected from patients undergoing arthroscopic shoulder surgery for rotator-cuff tears and control samples of subscapularis tendon from ten patients with normal rotator cuffs undergoing arthroscopic stabilisation of the shoulder were also obtained. These were all evaluated using semiquantitative reverse transcription polymerase chain-reaction and immunohistochemistry.

We identified significant upregulation of pro-inflammatory cytokines and apoptotic genes in the rodent model (p = 0.005). We further confirmed significantly increased levels of cytokine and apoptotic genes in human supraspinatus and subscapularis tendon harvested from patients with rotator cuff tears (p = 0.0008).

These findings suggest that pro-inflammatory cytokines may play a role in tendinopathy and may provide a target for preventing tendinopathies.

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

Objectives

Recent studies have shown that modulating inflammation-related lipid signalling after a bone fracture can accelerate healing in animal models. Specifically, decreasing 5-lipoxygenase (5-LO) activity during fracture healing increases cyclooxygenase-2 (COX-2) expression in the fracture callus, accelerates chondrogenesis and decreases healing time. In this study, we test the hypothesis that 5-LO inhibition will increase direct osteogenesis.

We isolated multilineage mesenchymal progenitor cells from haematomas collected from fracture sites. After the haematoma was manually removed from the fracture site it was cut into strips and cultured. Homogenous fibroblastic adherent cells were obtained. Flow cytometry revealed that the adherent cells were consistently positive for mesenchymal stem-cell-related markers CD29, CD44, CD105 and CD166, and were negative for the haemopoietic markers CD14, CD34, CD45 and CD133 similar to bone-marrow-derived mesenchymal stem cells. In the presence of lineage-specific induction factors the adherent cells could differentiate in vitro into osteogenic, chondrogenic and adipogenic cells.

Our results indicate that haematomas found at a fracture site contain multilineage mesenchymal progenitor cells and play an important role in bone healing. Our findings imply that to enhance healing the haematoma should not be removed from the fracture site during osteosynthesis.

Osteoarthritis (OA) is an important cause of pain, disability and economic loss in humans, and is similarly important in the horse. Recent knowledge on post-traumatic OA has suggested opportunities for early intervention, but it is difficult to identify the appropriate time of these interventions. The horse provides two useful mechanisms to answer these questions: 1) extensive experience with clinical OA in horses; and 2) use of a consistently predictable model of OA that can help study early pathobiological events, define targets for therapeutic intervention and then test these putative therapies. This paper summarises the syndromes of clinical OA in horses including pathogenesis, diagnosis and treatment, and details controlled studies of various treatment options using an equine model of clinical OA.

Frozen shoulder is commonly encountered in general orthopaedic practice. It may arise spontaneously without an obvious predisposing cause, or be associated with a variety of local or systemic disorders. Diagnosis is based upon the recognition of the characteristic features of the pain, and selective limitation of passive external rotation. The macroscopic and histological features of the capsular contracture are well-defined, but the underlying pathological processes remain poorly understood. It may cause protracted disability, and imposes a considerable burden on health service resources. Most patients are still managed by physiotherapy in primary care, and only the more refractory cases are referred for specialist intervention. Targeted therapy is not possible and treatment remains predominantly symptomatic. However, over the last ten years, more active interventions that may shorten the clinical course, such as capsular distension arthrography and arthroscopic capsular release, have become more popular.

This review describes the clinical and pathological features of frozen shoulder. We also outline the current treatment options, review the published results and present our own treatment algorithm.

Low bone mass and osteopenia have been described in the axial and peripheral skeleton of patients with adolescent idiopathic scoliosis (AIS). Recently, many studies have shown that gene polymorphism is related to osteoporosis. However, no studies have linked the association between IL6 gene polymorphism and bone mass in AIS. This study examined the association between bone mass and IL6 gene polymorphism in 198 girls with AIS. The polymorphisms of IL6-597 G→A, IL6-572 G→C and IL6-174 G→A and the bone mineral density in the lumbar spine and femoral neck were analysed and compared with their levels in healthy controls. The mean bone mineral density at both sites in patients with AIS was decreased compared with controls (p = 0.0022 and p = 0.0013, respectively). Comparison of genotype frequencies between AIS and healthy controls revealed a statistically significant difference in IL6-572 G→C polymorphism (p = 0.0305). There was a significant association between the IL6-572 G→C polymorphism and bone mineral density in the lumbar spine, with the CC genotype significantly higher with the GC (p = 0.0124) or GG (p = 0.0066) genotypes.

These results suggest that the IL6-572 G→C polymorphism is associated with bone mineral density in the lumbar spine in Korean girls with AIS.

Various chemicals are commonly used as adjuvant treatment to surgery for giant-cell tumour (GCT) of bone. The comparative effect of these solutions on the cells of GCT is not known. In this study we evaluated the cytotoxic effect of sterile water, 95% ethanol, 5% phenol, 3% hydrogen peroxide (H₂O₂) and 50% zinc chloride (ZnCI₂) on GCT monolayer tumour cultures which were established from six patients. The DNA content, the metabolic activity and the viability of the cultured samples of tumour cells were assessed at various times up to 120 hours after their exposure to these solutions.

Equal cytotoxicity to the GCT monolayer culture was observed for 95% ethanol, 5% phenol, 3% H₂O₂ and 50% ZnCI₂. The treated samples showed significant reductions in DNA content and metabolic activity 24 hours after treatment and this was sustained for up to 120 hours. The samples treated with sterile water showed an initial decline in DNA content and viability 24 hours after treatment, but the surviving cells were viable and had proliferated. No multinucleated cell formation was seen in these cultures.

These results suggest that the use of chemical adjuvants other than water could help improve local control in the treatment of GCT of bone.

We have used Fourier transform infrared spectroscopy (FTIR) to characterise the chemical and structural composition of the tendons of the rotator cuff and to identify structural differences among anatomically distinct tears. Such information may help to identify biomarkers of tears and to provide insight into the rates of healing of different sizes of tear. The infrared spectra of 81 partial, small, medium, large and massive tears were measured using FTIR and compared with 11 uninjured control tendons. All the spectra were classified using standard techniques of multivariate analysis.

FTIR readily differentiates between normal and torn tendons, and different sizes of tear. We identified the key discriminating molecules and spectra altered in torn tendons to be carbohydrates/phospholipids (1030 cm⁻¹ to 1200 cm⁻¹), collagen (1300 cm⁻¹ to 1700 cm⁻¹ and 3000 cm⁻¹ to 3350 cm⁻¹) and lipids (2800 cm⁻¹ to 3000 cm⁻¹).

Our study has shown that FTIR spectroscopy can identify tears of the rotator cuff of varying size based upon distinguishable chemical and structural features. The onset of a tear is mainly associated with altered structural arrangements of collagen, with changes in lipids and carbohydrates. The approach described is rapid and has the potential to be used peri-operatively to determine the quality of the tendon and the extent of the disease, thus guiding surgical repair.

We undertook a prospective study to evaluate the prognostic significance of the serum levels of vascular endothelial growth factor (VEGF) in predicting the survival of patients with osteosarcoma. The levels were measured by an enzyme-linked immunosorbent assay in 15 patients with osteosarcoma before commencing treatment. The patients were divided into two groups, with a high or a low serum VEGF level, and the incidence of metastases and overall survival rate were compared.

No significant relationship was observed between the serum VEGF levels and gender, age, the size of the tumour or the response to pre-operative chemotherapy. Patients with a serum VEGF > 1000 pg/ml had significantly worse survival than those with a level < 1000 pg/ml (p = 0.002). The serum VEGF level may be useful in predicting the prognosis for survival in patients with osteosarcoma.

The mammalian growth plate is a complex structure which is essential for the elongation of long bones. However, an understanding of how the growth plate functions at the cellular level is lacking. This review, summarises the factors involved in growth-plate regulation, its failure and the consequence of injury. We also describe some of the cellular mechanisms which underpin the increase in volume of the growth-plate chondrocyte which is the major determinant of the rate and extent of bone lengthening. We show how living in situ chondrocytes can be imaged using 2-photon laser scanning microscopy to provide a quantitative analysis of their volume. This approach should give better understanding of the cellular control of bone growth in both healthy and failed growth plates.

We have performed a prospective double-blind, randomised controlled trial over two years to evaluate the efficacy and safety of an intra-operative peri-articular injection of triamcinolone acetonide in patients undergoing medial unicondylar knee replacement. We randomised 90 patients into two equal groups. The study group received an injection of triamcinolone acetonide, bupivacaine, and epinephrine into the peri-articular tissues at the end of the operation. The control group received the same injection mixture but without the addition of triamcinolone. The peri-operative analgesic regimen was standardised.

The study group reported a significant reduction in pain (p = 0.014 at 12 hours, p = 0.031 at 18 hours and p = 0.031 at 24 hours) and had a better range of movement (p = 0.023 at three months). There was no significant difference in the rate of infection and no incidence of tendon rupture in either group.

The addition of corticosteroid to the peri-articular injection after unicondylar knee replacement had both immediate and short-term benefits in terms of relief from pain, and rehabilitation with no increased risk of infection.

We have undertaken a prospective study in patients with a fracture of the femoral shaft requiring intramedullary nailing to test the hypothesis that the femoral canal could be a potential source of the second hit phenomenon. We determined the local femoral intramedullary and peripheral release of interleukin-6 (IL-6) after fracture and subsequent intramedullary reaming.

In all patients, the fracture caused a significant increase in the local femoral concentrations of IL-6 compared to a femoral control group. The concentration of IL-6 in the local femoral environment was significantly higher than in the patients own matched blood samples from their peripheral circulation. The magnitude of the local femoral release of IL-6 after femoral fracture was independent of the injury severity score and whether the fracture was closed or open.

In patients who underwent intramedullary reaming of the femoral canal a further significant local release of IL-6 was demonstrated, providing evidence that intramedullary reaming can cause a significant local inflammatory reaction.

This paper reviews the current literature concerning the main clinical factors which can impair the healing of fractures and makes recommendations on avoiding or minimising these in order to optimise the outcome for patients. The clinical implications are described.

In an attempt to increase the life of cementless prostheses, an hydroxyapatite-coated implant which releases a bisphosphonate has been suggested as a drug-delivery system. Our in vitro study was designed to determine the maximum dose to which osteoblasts could be safely exposed.

Our findings demonstrated that zoledronate did not impair the proliferation of human osteoblasts when used at concentrations below 1 μm. Murine cells can be exposed to concentrations as high as 10 μm.

A concentration of 0.01% of titanium particles did not impair the proliferation of either cell line. Zoledronate affected the alkaline phosphatase activity of murine osteoblasts through a chelation phenomenon. The presence of titanium particles strongly decreased the alkaline phosphatase activity of murine osteoblasts. We did not detect any synergic effect of zoledronate and titanium particles on the behaviour of both human and murine osteoblasts.