CHONDROCYTE APOPTOSIS IN RESPONSE TO DISLOCATION OF THE HIP IN THE RAT MODEL

Impact of endoplasmic reticulum stress on chondrocyte apoptosis in rat model of DDH

Developmental dysplasia of the hip (DDH) is a developmental disorder characterized by acetabular dysplasia leading to early osteoarthritis. This study examines the role of endoplasmic reticulum stress (ERS) in chondrocyte apoptosis and cartilage degeneration within a DDH model. In the rat model of DDH, created using a swaddling technique, significant deformities in the femoral head and acetabulum were observed, alongside an upregulation of matrix metalloproteinase-13 in acetabular cartilage. We also noted increased levels of apoptosis and ERS-related factors in the acetabular cartilage of DDH models. Additionally, rat chondrocytes exposed to high-magnitude cyclic tensile strain (CTS, 1 Hz, 10% equibiaxial strain) in vitro exhibited elevated ERS and increased apoptosis. Importantly, treatment with the ERS inhibitor 4-phenylbutyric acid effectively suppressed apoptosis induced by CTS in chondrocytes. Our findings suggest that ERS contributes to the upregulation of apoptosis-related factors in chondrocytes within the DDH model, indicating the potential of ERS modulation as a therapeutic approach for DDH-related cartilage degeneration.

Medium-term outcome and classification of traumatic anterior hip dislocations

INTRODUCTION

Traumatic anterior hip dislocations are subdivided to obturator (inferior) and pubic (superior) dislocations by Epstein's descriptive classification. This rare injury is thought to have favourable clinical outcomes. The incidence of associated femoral head and acetabular injuries has been low in past case series. We sought to revisit this injury and classification in the era of advanced imaging and contemporary surgical techniques.

MATERIALS AND METHODS

A retrospective study of 15 patients treated for anterior hip dislocation was performed. Medical records were reviewed for demographic and surgical data. Imaging studies were revisited to determine direction of dislocation and associated fractures. Patients were assessed for pain, hip function using the modified Harris Hip Score (mHHS), hip range of motion and radiographic changes. Mean follow-up time was 3 years.

RESULTS

Anterior dislocation occurred in an obturator (inferior), pubic (superior) or central direction. 9 patients had concomitant femoral head impaction and 7 patients suffered from acetabular fractures. 8 patients with an anterior hip dislocation underwent surgical treatment. This therapy, along with early range of motion and weight bearing, produced favourable clinical outcomes with 9 patients reporting no pain and an average mHHS of 83.8. 6 patients had heterotopic ossification at latest follow-up.

CONCLUSIONS

Traumatic anterior hip dislocation is commonly associated with femoral head impaction and acetabular injuries which should be addressed operatively when appropriate to produce favourable results. In this paper, we propose a revision to the commonly used descriptive classification system.

Modulation of cartilage's response to injury: Can chondrocyte apoptosis be reversed?

Osteoarthritis is characterized by a chronic, progressive and irreversible degradation of the articular cartilage associated with joint inflammation and a reparative bone response. More than 100 million people are affected by this condition worldwide with significant health and welfare costs. Our available treatment options in osteoarthritis are extremely limited. Chondral or osteochondral grafts have shown some promising results but joint replacement surgery is by far the most common therapeutic approach. The difficulty lies on the limited regeneration capacity of the articular cartilage, poor blood supply and the paucity of resident progenitor stem cells. In addition, our poor understanding of the molecular signalling pathways involved in the senescence and apoptosis of chondrocytes is a major factor restricting further progress in the area. This review focuses on molecules and approaches that can be implemented to delay or even rescue chondrocyte apoptosis. Ways of modulating the physiologic response to trauma preventing chondrocyte death are proposed. The use of several cytokines, growth factors and advances made in altering several of the degenerative genetic pathways involved in chondrocyte apoptosis and degradation are also presented. The suggested approaches can help clinicians to improve cartilage tissue regeneration.

Emergent surgical reduction and fixation for Pipkin type I femoral fractures

The purpose of this study was to assess the effect of timing of large fragment fixation in patients with Pipkin type-I fractures. Patients with Pipkin type-I fractures from the authors' trauma center were prospectively observed between July 2007 and July 2010. Fragments that constituted more than one-fourth of the femoral head were included. Thirty-six patients were equally randomized to undergo emergent surgical reduction and fixation or secondary operative fixation after emergent closed reduction. No significant differences existed between the 2 groups with regard to the baseline characteristics, operating time, and blood loss (P>.05). However, the emergent surgical reduction and fixation group had a shorter hospital stay (P<.05). The results after more than 2-year follow-up showed that the complication and avascular necrosis rates were higher in the secondary operative fixation after emergent closed reduction group compared with the emergent surgical reduction and fixation group (P<.05). It was difficult to achieve an anatomically reduced femoral head when the fragments constituted more than one-fourth of the femoral head. Patients who underwent secondary operative fixation after emergent closed reduction had a high avascular necrosis rate and a relatively poor outcome. Emergent surgical reduction and fixation should be performed shortly after injury to enhance the treatment outcome.