Effect of low-dose irradiation on structural and mechanical properties of hyaline cartilage-like fibrocartilage.

OBJECTIVE: The aim of this study was to analyze the effect of low-dose irradiation on fibrous cartilage and to obtain a hyaline cartilage-like fibrocartilage (HCLF) with similar structural and mechanical properties to hyaline cartilage. METHODS: An osteochondral defect was created in 40 knees of 20 rabbits. At the 7th postoperative day, a single knee of each rabbit was irradiated with a total dose of 5.0 Gy in 1.0 Gy fractions for 5 days (radiotherapy group), while the other knee was not irradiated (control group). Rabbits were then divided into four groups of 5 rabbits each. The first three groups were sacrificed at the 4th, 8th and the 12th postoperative weeks and cartilage defects were macroscopically and microscopically evaluated. The remaining group of 5 rabbits was sacrificed at the 12th week and biomechanical compression tests were performed on the cartilage defects. RESULTS: There was no significant biomechanical difference between the radiotherapy and the control group (p=0.686). There was no significant macroscopic and microscopic difference between groups (p=0.300). Chondrocyte clustering was observed in the irradiated group. CONCLUSION: Low-dose irradiation does not affect the mechanical properties of HCLF in vivo. However, structural changes such as chondrocyte clustering were observed.

Acetabular reconstruction by impacted cancellous allografts in cementless total hip arthroplasty revision.

OBJECTIVE: The aim of this study was to evaluate the primary and secondary stability, where 100% or virtually 100% of the uncemented acetabular component contacted with impacted cancellous allografts, focusing especially on the amount of graft used and rim contact. METHODS: Fifteen cases of acetabular reconstruction using impacted cancellous allografts and cementless porous-coated component in which 100% or virtually 100% of the component contacted only with the allograft were reviewed. Mean follow-up was 97.5 (range: 58 to 130) months after revision. The Harris hip score was used to evaluate clinical results. Radiographic evaluations were done using standard anteroposterior views obtained at the final follow-up. RESULTS: Two patients underwent re-revision. The mean Harris hip score of the remaining 13 patients was 88.3±11.9 (range: 68 to 100) at the final follow-up. Early postoperative radiographs showed mean angle of inclination of 45° (range: 30° to 55°). There was a mean migration of 6.2±7.8 (range: 0 to 29) mm and the migration amount did not differ according to rim contact (p=0.054). There was no correlation between migration and amount of graft used (p>0.05). There was a significant correlation between migration and follow-up time (p<0.01). CONCLUSION: Our results imply that 50% host bone contact is not absolutely necessary to form a stable construct while restoring the centre of hip rotation.

[An evaluation of knee ligament injuries encountered in skiers at the Uludag Ski Center]. / Uludag Kayak Merkezi'nde kayakçilarda görülen diz bag yaralanmalarinin degerlendirilmesi.

OBJECTIVES: We evaluated the frequency, anatomic types, and predisposing factors of knee ligament injuries that occur in skiers during a winter season at the Uludag Ski Center, Bursa, Turkey. METHODS: A total of 215 patients (240 knees) presented to the Uludag University-Sabanci Health Center after sustaining a skier knee injury during the 2003-2004 winter season. The mean patient age was 31 years (range 9 to 55 years). Knee ligament injuries were assessed according to the AOSSM (American Orthopaedic Society for Sports Medicine) criteria. Cumulative data were collected from patient records and from a questionnaire administered to 100 healthy skiers. RESULTS: The mean knee injury rate was 1.14 injuries per 1000 skier-days. The mean length of time between the occurrence of knee injuries was 875 skier-days. The most frequently injured ligament was the interior cruciate ligament (35.4%) followed by the anterior cruciate ligament (27.1%). Knee ligament injuries were significantly more common in skiers than in snowboarders (odds ratio 6.83, p<0.001). Hard and steep pists were associated with a two-fold risk for knee ligament injuries (odds ratio 2.28, p<0.001). For the occurrence of knee injuries, no significant differences were found with respect to sex and age. CONCLUSION: The interior and the anterior cruciate ligaments are the most commonly injured ligaments in skiers. Two risk factors concerning the equipment (ski) and the environment (hard pists) play a significant role in the occurrence of knee injuries.