Meniscal degeneration in human knee osteoarthritis: in situ hybridization and immunohistochemistry study

OBJECTIVE

Meniscus injury is one of the causes of secondary osteoarthritis (OA). However, the role of meniscus is still unclear. Human meniscal distribution of cells and cartilage oligomeric matrix protein (COMP) and their changes in advanced OA were analyzed.

PATIENTS AND METHODS

Thirty-one medial menisci from patients with knee OA that underwent a total knee arthroplasty were studied. Normal meniscal tissue was obtained from partial arthroscopic meniscectomy. Meniscal samples were processed for histology, immunohistochemistry and in situ hybridization, for cell assessment including density, active divisions, apoptosis, COMP distribution and proteoglycan content.

RESULTS

Osteoarthritic menisci demonstrated areas of cell depletion and significant decrease in COMP immunostaining. Actively dividing cells were only found in the meniscectomy group, but not in the osteoarthritic group. Proteoglycan staining was less prominent in menisci from the osteoarthritis group.

CONCLUSIONS

Our results show a decreased cell population, with low COMP and altered matrix organization in osteoarthritis menisci that suggest an altered meniscal scaffold and potential impairment of meniscal function. These meniscal changes may be associated with the development of knee osteoarthritis.

Evaluation of a minimally aggressive method of patellofemoral osteoarthritis treatment at 10 years minimum follow-up

BACKGROUND

Knee osteoarthritis mainly affecting the lateral facet of the patella, especially in young patients, is a definite challenge to the surgeon. Our purpose was to investigate the long-term outcome of a simple operation such as the partial lateral facetectomy on middle-aged to elderly patients with predominant lateral patellofemoral osteoarthritis.

METHODS

A retrospective, long-term study of 39 knees (28 females, mean aged at surgery 61yearsold) with a minimum follow-up of 10years was performed. Evaluations included preoperative and postoperative questionnaires, physical examinations, and radiographs.

RESULTS

The main outcomes included the initial anterior pain relief, with higher scores using the Knee Society Score (that improved in 84% of the knees), and the eventual failure of the technique, including percentage of patients that required secondary total knee replacement (30% of the knees).

CONCLUSION

Partial lateral facetectomy aiming to decrease the high pressure in the lateral facet of the patella confirmed frequent pain relief. This surgical procedure being minimally invasive, relatively simple, and effective in selected patients, is a valid early alternative to more complex operations and does not preclude further reconstructive surgery in case of disease progression.

An experimental study of COMP (cartilage oligomeric matrix protein) in the rabbit menisci

INTRODUCTION

Secondary knee osteoarthritis (OA) is currently associated with meniscal injuries, but the pathogenesis is unclear. We analyzed the distribution of cells and cartilage oligomeric matrix protein (COMP) and its changes in the early stages of degeneration in meniscus.

METHOD

Ten New Zealand rabbits underwent anterior cruciate ligament (ACL)-transection of the right knee-joint. Left knee-joints were used as controls. The animals were killed at 4 and 12 weeks. Gross injuries in meniscus and articular cartilage were scored. Meniscal tissues were immunostained with a specific antibody against COMP, with Ki-67, using TUNEL-assay and alcian blue stain. The number of cells was counted.

RESULTS

At 4 weeks post-ACL-transection, 2/5 of the operated knees showed articular damages and medial menisci tears. Menisci showed a weak increase of cells, higher in cells under division and an increase of apoptosis, COMP and proteoglycans. At 12 weeks, 5/5 of the medial menisci and 2/5 of lateral menisci presented tears, and osteoarthritic changes were seen in the cartilage of all the operated knees. Meniscal cells reverted to normal number, while active cell division decreased below normal, apoptotic events were still high, COMP remained elevated, and glycosaminoglycans were even more elevated.

CONCLUSION

Extracellular matrix changes and altered cell distribution occur early in the degenerative meniscus. There is a close relationship between changes in the articular cartilage and the menisci at the onset of secondary OA.