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The Journal of Bone & Joint Surgery British Volume
Vol. 81-B, Issue 4 | Pages 732 - 738
1 Jul 1999
Meek RMD McLellan S Crossan JF

Dupuytren’s disease is a chronic inflammatory process which produces contractures of the fingers. The nodules present in Dupuytren’s tissue contain inflammatory cells, mainly lymphocytes and macrophages. These express a common integrin known as VLA4. The corresponding binding ligands to VLA4 are vascular cell adhesion molecule-1 (VCAM-1) present on the endothelial cells and the CS1 sequence of the fibronectin present in the extracellular matrix. Transforming growth factor-beta (TGF-ß) is a peptide hormone which has a crucial role in the process of fibrosis. We studied tissue from 20 patients with Dupuytren’s disease, four samples of normal palmar fascia from patients undergoing carpal tunnel decompression and tissue from ten patients who had received perinodular injections of depomedrone into the palm five days before operation. The distribution of VLA4, VCAM-1, CS1 fibronectin and TGF-ß was shown by immunohistochemistry using an alkaline phosphorylase method for light microscopy. In untreated Dupuytren’s tissue CS1 fibronectin stained positively around the endothelial cells of blood vessels and also around the surrounding myofibroblasts, principally at the periphery of many of the active areas of the Dupuytren’s nodule. VCAM-1 stained very positively for the endothelial cells of blood vessels surrounding and penetrating the areas of high nodular activity. VCAM-1 was more rarely expressed outside the blood vessels. VLA4 was expressed by inflammatory cells principally in and around the blood vessels expressing VCAM-1 and CS1 but also on some cells spreading into the nodule. TGF-ß stained positively around the inflammatory cells principally at the perivascular periphery of nodules. These cells often showed VLA4 expression and co-localised with areas of strong production of CS1 fibronectin. Normal palmar fascia contained only scanty amounts of CS1 fibronectin, almost no VCAM-1 and only an occasional cell staining positively for VLA4 or TGF-ß. In the steroid-treated group, VCAM-1 expression was downregulated in the endothelium of perinodular blood vessels and only occasional inflammatory cell expression remained. Expression of CS1 fibronectin was also much reduced but still occurred in the blood vessels and around the myofibroblast stroma. VLA4-expressing cells were also reduced in numbers. A similar but reduced distribution of production of TGF-ß was also noted. Our findings show that adherence of inflammatory cells to the endothelial wall and the extravasation into the periphery of the nodule may be affected by steroids, which reduce expression of VCAM-1 in vivo. This indicates that therapeutic intervention to prevent the recommencement of the chronic inflammatory process and subsequent fibrosis necessitating further surgery may be possible


The Journal of Bone & Joint Surgery British Volume
Vol. 79-B, Issue 1 | Pages 147 - 153
1 Jan 1997
Brown MF Hukkanen MVJ McCarthy ID Redfern DRM Batten JJ Crock HV Hughes SPF Polak JM

We obtained intervertebral discs with cartilage endplates and underlying cancellous bone at operation from patients with degenerative disc disease and then used immunohistochemical techniques to localise the nerves and nerve endings in the specimens. We used antibodies for the ubiquitous neuronal protein gene product 9.5 (PGP 9.5). Immunoreactivity to neuropeptide Y was used to identify autonomic nerves and calcitonin gene-related peptide (CGRP) and substance P to identify sensory nerves. Blood vessels were identified by immunoreactivity with platelet-endothelial cell-adhesion molecule (CD31; PECAM). In a control group with no known history of chronic back pain, nerve fibres immunoreactive to PGP 9.5 and neuropeptide Y were most closely related to blood vessels, with occasional substance P and CGRP immunoreactivity. In patients with severe back pain and markedly reduced disc height, proliferation of blood vessels and accompanying nerve fibres was observed in the endplate region and underlying vertebral bodies. Many of these nerves were immunoreactive to substance P or CGRP, and in addition, substance P- and CGRP-immunoreactive nociceptors were seen unrelated to blood vessels. Quantification by image analysis showed a marked increase in CGRP-containing sensory nerve fibres compared with normal control subjects. We speculate that a chemotactic response to products of disc breakdown is responsible for the proliferation of vascularity and CGRP-containing sensory nerves found in the endplate region and vertebral body adjacent to degenerate discs. The neuropeptides substance P and CGRP have potent vasodilatory as well as pain-transmitting effects. The increase in sensory nerve endings suggests increase in blood flow, perhaps as an attempt to augment the nutrition of the degenerate disc. The increase in the density of sensory nerves, and the presence of endplate cartilage defects, strongly suggest that the endplates and vertebral bodies are sources of pain; this may explain the severe pain on movement experienced by some patients with degenerative disc disease


The Journal of Bone & Joint Surgery British Volume
Vol. 85-B, Issue 4 | Pages 604 - 610
1 May 2003
Reed AAC Joyner CJ Isefuku S Brownlow HC Simpson AHRW

Our aim was to develop a clinically relevant model of atrophic nonunion in the rat to test the hypothesis that the vessel density of atrophic nonunion reaches that of normal healing bone, but at a later time-point. Atrophic nonunion is usually attributed to impaired blood supply and is poorly understood. We determined the number of blood vessels at the site of an osteotomy using immunolocalisation techniques in both normally healing bones and in atrophic nonunion. At one week after operation there were significantly fewer blood vessels in the nonunion group than in the healing group. By eight weeks, the number in the atrophic nonunion group had reached the same level as that in the healing group. Our findings suggest that the number of blood vessels in atrophic nonunion reaches the same level as that in healing bone, but at a later time-point. Diminished vascularity within the first three weeks, but not at a later time-point, may prevent fractures from uniting


The Journal of Bone & Joint Surgery British Volume
Vol. 84-B, Issue 1 | Pages 141 - 144
1 Jan 2002
Petersen W Hohmann G Stein V Tillmann B

We studied the vascular pattern of human posterior tibial tendons by injection techniques and immunohistochemically using antibodies against laminin. The intravascular volume of the posterior tibial tendon was determined using a new method of injection of a solution of . 99m. Tc and gelatin ink into the lower legs of cadavers. Three segments of 1 cm length from different regions of the human posterior tibial tendon were measured using a gamma well counter. The main blood supply arises from the posterior tibial artery. Blood vessels enter the paratenon of the posterior tibial tendon via a mesotenon from the posterior aspect. From the paratenon, the blood vessels penetrate the posterior tibial tendon and anastomose with a longitudinally orientated intratendinous network. The number of vessels in the substance of the tendon is consistently less than that in the surrounding paratenon. The distribution of blood vessels within the posterior tibial tendon is not homogeneous. In the retromalleolar region the intravascular volume was significantly reduced with a mean value of 15 μl/g of tendon tissue. There was no significant difference between the mean intravascular volumes of the proximal and distal areas (distal, 27.7 μl/g tendon tissue; proximal, 30 μl/g tendon tissue). The immunohistochemical investigation showed that there was no immunostaining for laminin in the anterior part of the tendon in the region where it passes behind the medial malleolus. This region is avascular. The most frequent site of rupture of the posterior tibial tendon is in the region behind the medial malleolus. A potential endogenous risk factor may be the limited healing potential of avascular tissue


The Journal of Bone & Joint Surgery British Volume
Vol. 81-B, Issue 3 | Pages 531 - 537
1 May 1999
Corbett SA Hukkanen M Batten J McCarthy ID Polak JM Hughes SPF

Our aim was to investigate whether nitric oxide synthase (NOS) isoforms, responsible for the generation of NO, are expressed during the healing of fractures. To localise the sites of expression compared with those in normal bone we made standardised, stabilised, unilateral tibial fractures in male Wistar rats. Immunostaining was used to determine the precise tissue localisation of the different NOS isoforms. Western blotting was used to assess expression of NOS isoform protein and L-citrulline assays for studies on NOS activity. Control tissue was obtained from both the contralateral uninjured limb and limbs of normal rats. Immunohistochemistry showed increased expression of endothelial NOS (eNOS) to be strongest in the cortical blood vessels and in osteocytes in the early phase of fracture repair. Western blot and image analysis confirmed this initial increase. Significantly elevated calcium-dependent NOS activity was observed at day 1 after fracture. Inducible NOS (iNOS) was localised principally in endosteal osteoblasts and was also seen in chondroblasts especially in the second week of fracture healing. Western blotting showed a reduction in iNOS during the early healing period. Significantly reduced calcium-independent NOS activity was also seen. No neuronal NOS was seen in either fracture or normal tissue. Increased eNOS in bone blood vessels is likely to mediate the increased blood flow recognised during fracture healing. eNOS expression in osteocytes may occur in response to changes in either mechanical or local fluid shear stress. The finding that eNOS is increased and iNOS reduced in early healing of fractures may be important in their successful repair


The Journal of Bone & Joint Surgery British Volume
Vol. 80-B, Issue 1 | Pages 151 - 155
1 Jan 1998
Ahmed M Bergström J Lundblad H Gillespie WJ Kreicbergs A

We studied the presence of sensory nerves by immunohistochemistry in the interface membranes of hip prostheses after aseptic loosening. Substance P (SP), neurokinin A (NKA) and calcitonin gene-related peptide (CGRP) were analysed as was protein gene product (PGP) 9.5, a general marker for nerve fibres. We identified nerve fibres in all samples but differences in their density were found. SP- and NKA-positive fibres were predominantly non-vascular, forming varicose nerve terminals. CGRP-immunoreactive nerve fibres with varicose terminals were seen mostly close to blood vessels, but also as free nerve endings. Sensory neuropeptides participate not only in nociception but also stimulate immune cells to release cytokines. The presence of sensory nerves in the interface membrane may reflect a pathophysiological response contributing to the aseptic loosening of hip prostheses


Bone & Joint Research
Vol. 6, Issue 2 | Pages 98 - 107
1 Feb 2017
Kazemi D Shams Asenjan K Dehdilani N Parsa H

Objectives

Mesenchymal stem cells have the ability to differentiate into various cell types, and thus have emerged as promising alternatives to chondrocytes in cell-based cartilage repair methods. The aim of this experimental study was to investigate the effect of bone marrow derived mesenchymal stem cells combined with platelet rich fibrin on osteochondral defect repair and articular cartilage regeneration in a canine model.

Methods

Osteochondral defects were created on the medial femoral condyles of 12 adult male mixed breed dogs. They were either treated with stem cells seeded on platelet rich fibrin or left empty. Macroscopic and histological evaluation of the repair tissue was conducted after four, 16 and 24 weeks using the International Cartilage Repair Society macroscopic and the O’Driscoll histological grading systems. Results were reported as mean and standard deviation (sd) and compared at different time points between the two groups using the Mann-Whitney U test, with a value < 0.05 considered statistically significant.


Objectives

Degenerative disc disease (DDD) and osteoarthritis (OA) are relatively frequent causes of disability amongst the elderly; they constitute serious socioeconomic costs and significantly impair quality of life. Previous studies to date have found that aggrecan variable number of tandem repeats (VNTR) contributes both to DDD and OA. However, current data are not consistent across studies. The purpose of this study was to evaluate systematically the relationship between aggrecan VNTR, and DDD and/or OA.

Methods

This study used a highly sensitive search strategy to identify all published studies related to the relationship between aggrecan VNTR and both DDD and OA in multiple databases from January 1996 to December 2016. All identified studies were systematically evaluated using specific inclusion and exclusion criteria. Cochrane methodology was also applied to the results of this study.


Bone & Joint Research
Vol. 6, Issue 5 | Pages 277 - 283
1 May 2017
Yoshikawa M Nakasa T Ishikawa M Adachi N Ochi M

Objectives

Regenerative medicine is an emerging field aimed at the repair and regeneration of various tissues. To this end, cytokines (CKs), growth factors (GFs), and stem/progenitor cells have been applied in this field. However, obtaining and preparing these candidates requires invasive, costly, and time-consuming procedures. We hypothesised that skeletal muscle could be a favorable candidate tissue for the concept of a point-of-care approach. The purpose of this study was to characterize and confirm the biological potential of skeletal muscle supernatant for use in regenerative medicine.

Methods

Semitendinosus muscle was used after harvesting tendon from patients who underwent anterior cruciate ligament reconstructions. A total of 500 milligrams of stripped muscle was minced and mixed with 1 mL of saline. The collected supernatant was analysed by enzyme-linked immunosorbent assay (ELISA) and flow cytometry. The biological effects of the supernatant on cell proliferation, osteogenesis, and angiogenesis in vitro were evaluated using human mesenchymal stem cells (hMSCs) and human umbilical cord vein endothelial cells (HUVECs).


Bone & Joint Research
Vol. 5, Issue 1 | Pages 11 - 17
1 Jan 2016
Barlow JD Morrey ME Hartzler RU Arsoy D Riester S van Wijnen AJ Morrey BF Sanchez-Sotelo J Abdel MP

Aims

Animal models have been developed that allow simulation of post-traumatic joint contracture. One such model involves contracture-forming surgery followed by surgical capsular release. This model allows testing of antifibrotic agents, such as rosiglitazone.

Methods

A total of 20 rabbits underwent contracture-forming surgery. Eight weeks later, the animals underwent a surgical capsular release. Ten animals received rosiglitazone (intramuscular initially, then orally). The animals were sacrificed following 16 weeks of free cage mobilisation. The joints were tested biomechanically, and the posterior capsule was assessed histologically and via genetic microarray analysis.


Bone & Joint Research
Vol. 1, Issue 9 | Pages 218 - 224
1 Sep 2012
Tabuchi K Soejima T Kanazawa T Noguchi K Nagata K

Objectives

The purpose of this study was to evaluate chronological changes in the collagen-type composition at tendon–bone interface during tendon–bone healing and to clarify the continuity between Sharpey-like fibres and inner fibres of the tendon.

Methods

Male white rabbits were used to create an extra-articular bone–tendon graft model by grafting the extensor digitorum longus into a bone tunnel. Three rabbits were killed at two, four, eight, 12 and 26 weeks post-operatively. Elastica van Gieson staining was used to colour 5 µm coronal sections, which were examined under optical and polarised light microscopy. Immunostaining for type I, II and III collagen was also performed.


The Journal of Bone & Joint Surgery British Volume
Vol. 92-B, Issue 3 | Pages 448 - 453
1 Mar 2010
Benson RT McDonnell SM Knowles HJ Rees JL Carr AJ Hulley PA

The aim of this study was to investigate the occurrence of tissue hypoxia and apoptosis at different stages of tendinopathy and tears of the rotator cuff.

We studied tissue from 24 patients with eight graded stages of either impingement (mild, moderate and severe) or tears of the rotator cuff (partial, small, medium, large and massive) and three controls. Biopsies were analysed using three immunohistochemical techniques, namely antibodies against HIF-1α (a transcription factor produced in a hypoxic environment), BNip3 (a HIF-1α regulated pro-apoptotic protein) and TUNEL (detecting DNA fragmentation in apoptosis).

The HIF-1α expression was greatest in mild impingement and in partial, small, medium and large tears. BNip3 expression increased significantly in partial, small, medium and large tears but was reduced in massive tears. Apoptosis was increased in small, medium, large and massive tears but not in partial tears.

These findings reveal evidence of hypoxic damage throughout the spectrum of pathology of the rotator cuff which may contribute to loss of cells by apoptosis. This provides a novel insight into the causes of degeneration of the rotator cuff and highlights possible options for treatment.


The Journal of Bone & Joint Surgery British Volume
Vol. 92-B, Issue 4 | Pages 586 - 594
1 Apr 2010
Sonnabend DH Howlett CR Young AA

The establishment of a suitable animal model of repair of the rotator cuff is difficult since the presence of a true rotator cuff anatomically appears to be restricted almost exclusively to advanced primates. Our observational study describes the healing process after repair of the cuff in a primate model. Lesions were prepared and repaired in eight ‘middle-aged’ baboons. Two each were killed at four, eight, 12 and 15 weeks post-operatively. The bone-tendon repair zones were assessed macroscopically and histologically.

Healing of the baboon supraspinatus involved a sequence of stages resulting in the reestablishment of the bone-tendon junction. It was not uniform and occurred more rapidly at the sites of suture fixation than between them. Four weeks after repair the bone-tendon healing was immature. Whereas macroscopically the repair appeared to be healed at eight weeks, the Sharpey fibres holding the repair together did not appear in any considerable number before 12 weeks. By 15 weeks, the bone-tendon junction was almost, but not quite mature.

Our results support the use of a post-operative rehabilitation programme in man which protects the surgical repair for at least 12 to 15 weeks in order to allow maturation of tendon-to-bone healing.


Bone & Joint Research
Vol. 3, Issue 11 | Pages 310 - 316
1 Nov 2014
Tomaszewski R Bohosiewicz J Gap A Bursig H Wysocka A

Objectives

The aim of this experimental study on New Zealand’s white rabbits was to investigate the transplantation of autogenous growth plate cells in order to treat the injured growth plate. They were assessed in terms of measurements of radiological tibial varus and histological characteristics.

Methods

An experimental model of plate growth medial partial resection of the tibia in 14 New Zealand white rabbits was created. During this surgical procedure the plate growth cells were collected and cultured. While the second surgery was being performed, the autologous cultured growth plate cells were grafted at the right tibia, whereas the left tibia was used as a control group.


The Journal of Bone & Joint Surgery British Volume
Vol. 91-B, Issue 7 | Pages 973 - 976
1 Jul 2009
Kralinger F Unger S Wambacher M Smekal V Schmoelz W

The medial periosteal hinge plays a key role in fractures of the head of the humerus, offering mechanical support during and after reduction and maintaining perfusion of the head by the vessels in the posteromedial periosteum. We have investigated the biomechanical properties of the medial periosteum in fractures of the proximal humerus using a standard model in 20 fresh-frozen cadaver specimens comparable in age, gender and bone mineral density. After creating the fracture, we displaced the humeral head medial or lateral to the shaft with controlled force until complete disruption of the posteromedial periosteum was recorded. As the quality of periosteum might be affected by age and bone quality, the results were correlated with the age and the local bone mineral density of the specimens measured with quantitative CT.

Periosteal rupture started at a mean displacement of 2.96 mm (sd 2.92) with a mean load of 100.9 N (sd 47.1). The mean maximum load of 111.4 N (sd 42.5) was reached at a mean displacement of 4.9 mm (sd 4.2). The periosteum was completely ruptured at a mean displacement of 34.4 mm (sd 11.1). There was no significant difference in the mean distance to complete rupture for medial (mean 35.8 mm (sd 13.8)) or lateral (mean 33.0 mm (sd 8.2)) displacement (p = 0.589).

The mean bone mineral density was 0.111 g/cm3 (sd 0.035). A statistically significant but low correlation between bone mineral density and the maximum load uptake (r = 0.475, p = 0.034) was observed.

This study showed that the posteromedial hinge is a mechanical structure capable of providing support for percutaneous reduction and stabilisation of a fracture by ligamentotaxis. Periosteal rupture started at a mean of about 3 mm and was completed by a mean displacement of just under 35 mm. The microvascular situation of the rupturing periosteum cannot be investigated with the current model.


The Journal of Bone & Joint Surgery British Volume
Vol. 92-B, Issue 2 | Pages 298 - 303
1 Feb 2010
Toom A Suutre S Märtson A Haviko T Selstam G Arend A

We have developed an animal model to examine the formation of heterotopic ossification using standardised muscular damage and implantation of a beta-tricalcium phosphate block into a hip capsulotomy wound in Wistar rats. The aim was to investigate how cells originating from drilled femoral canals and damaged muscles influence the formation of heterotopic bone. The femoral canal was either drilled or left untouched and a tricalcium phosphate block, immersed either in saline or a rhBMP-2 solution, was implanted. These implants were removed at three and 21 days after the operation and examined histologically, histomorphometrically and immunohistochemically.

Bone formation was seen in all implants in rhBMP-2-immersed, whereas in those immersed in saline the process was minimal, irrespective of drilling of the femoral canals. Bone mineralisation was somewhat greater in the absence of drilling with a mean mineralised volume to mean total volume of 18.2% (sd 4.5) versus 12.7% (sd 2.9, p < 0.019), respectively.

Our findings suggest that osteoinductive signalling is an early event in the formation of ectopic bone. If applicable to man the results indicate that careful tissue handling is more important than the prevention of the dissemination of bone cells in order to avoid heterotopic ossification.


The Journal of Bone & Joint Surgery British Volume
Vol. 89-B, Issue 1 | Pages 116 - 120
1 Jan 2007
Laing AJ Dillon JP Condon E Coffey JC Street JT Wang JH McGuinness AJ Redmond HP

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 (MNCsca-1+) populations were then cultured and examined for functional vascular endothelial differentiation. Bone marrow MNCsca-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.


The Journal of Bone & Joint Surgery British Volume
Vol. 90-B, Issue 2 | Pages 246 - 253
1 Feb 2008
Coathup M Smith N Kingsley C Buckland T Dattani R Ascroft GP Blunn G

An experimental sheep model was used for impaction allografting of 12 hemiarthroplasty femoral components placed into two equal-sized groups. In group 1, a 50:50 mixture of ApaPore hydroxyapatite bone-graft substitute and allograft was used. In group 2, ApaPore and allograft were mixed in a 90:10 ratio. Both groups were killed at six months. Ground reaction force results demonstrated no significant differences (p > 0.05) between the two groups at 8, 16 and 24 weeks post-operatively, and all animals remained active. The mean bone turnover rates were significantly greater in group 1, at 0.00206 mm/day, compared to group 2 at 0.0013 mm/day (p < 0.05). The results for the area of new bone formation demonstrated no significant differences (p > 0.05) between the two groups. No significant differences were found between the two groups in thickness of the cement mantle (p > 0.05) and percentage ApaPore-bone contact (p > 0.05).

The results of this animal study demonstrated that a mixture of ApaPore allograft in a 90:10 ratio was comparable to using a 50:50 mixture.


The Journal of Bone & Joint Surgery British Volume
Vol. 87-B, Issue 7 | Pages 1006 - 1011
1 Jul 2005
Hatano H Ogose A Hotta T Endo N Umezu H Morita T

We examined osteochondral autografts, obtained at a mean of 19.5 months (3 to 48) following extracorporeal irradiation and re-implantation to replace bone defects after removal of tumours. The specimens were obtained from six patients (mean age 13.3 years (10 to 18)) and consisted of articular cartilage (five), subchondral bone (five), external callus (one) and tendon (one). The tumour cells in the grafts were eradicated by a single radiation dose of 60 Gy. In three cartilage specimens, viable chondrocytes were detected. The survival of chondrocytes was confirmed with S-100 protein staining. Three specimens from the subchondral region and a tendon displayed features of regeneration. Callus was seen at the junction between host and irradiated bone.


The Journal of Bone & Joint Surgery British Volume
Vol. 92-B, Issue 12 | Pages 1710 - 1716
1 Dec 2010
Chia W Pan R Tseng F Chen Y Feng C Lee H Chang D Sytwu H

The patellofemoral joint is an important source of symptoms in osteoarthritis of the knee. We have used a newly designed surgical model of patellar strengthening to induce osteoarthritis in BALB/c mice and to establish markers by investigating the relationship between osteoarthritis and synovial levels of matrix metalloproteinases (MMPs). Osteoarthritis was induced by using this microsurgical technique under direct vision without involving the cavity of the knee. Degeneration of cartilage was assessed by the Mankin score and synovial tissue was used to determine the mRNA expression levels of MMPs. Irrigation fluid from the knee was used to measure the concentrations of MMP-3 and MMP-9. Analysis of cartilage degeneration was correlated with the levels of expression of MMP.

After operation the patellofemoral joint showed evidence of mild osteoarthritis at eight weeks and further degenerative changes by 12 weeks. The level of synovial MMP-9 mRNA correlated with the Mankin score at eight weeks, but not at 12 weeks. The levels of MMP-2, MMP-3 and MMP-14 mRNA correlated with the Mankin score at 12 weeks. An increase in MMP-3 was observed from four weeks up to 16 weeks. MMP-9 was notably increased at eight weeks, but the concentration at 16 weeks had decreased to the level observed at four weeks.

Our observations suggest that MMP-2, MMP-3 and MMP-14 could be used as markers of the progression of osteoarthritic change.