The lifetime prevalence of symptomatic osteoarthritis at the knee is 50% osteoarthritis of the ankle occurs in only 1% of the population. This variation in prevalence has been hypothesised to result from the differential responsiveness of the joint cartilages to catabolic stimuli.

Human cartilage explants were taken from the talar domes (n=12) and the femoral condyles (n=7) following surgical amputation. Explants were cultured in the presence of either a combination of high concentration cytokines (TNFα, OSM, IL-1α) to resemble a post traumatic environment or low concentration cytokines to resemble a chronic osteoarthritic joint. Cartilage breakdown was measured by the percentage loss of Sulphated glycosaminoglycan (sGAG) from the explant to the media during culture. Expression levels of the pro-inflammatory molecules nitric oxide and prostaglandin E₂ were also measured.

Significantly more sGAG was lost from knee cartilage exposed to TNFα (22.2% vs 13.2%, P=0.01) and TNFα in combination with IL-1α (27.5% vs 16.0%, P=0.02) compared to the ankle; low cytokine concentrations did not affect sGAG release. Significantly more PGE₂ was produced by knee cartilage compared to ankle cartilage however no significant difference in nitrite production was noted.

Cartilage from the knee and ankle has a divergent response to stimulation by pro-inflammatory cytokines, with high concentrations of TNFα alone, or in combination with IL-1α amplifying cartilage degeneration. This differential response may account for the high prevalence of knee arthritis compared to ankle OA and provide a future pharmacological target to treat post traumatic arthritis of the knee.

Fractures of the shaft of the humerus are often treated conservatively in a hanging cast or a humeral brace. The conservative management of this fracture is often prolonged and quite uncomfortable for the patient. Some of the patients will need an operative fixation after a trial of conservative management.

We retrospectively looked at 72 consecutive patients with fractures of the shaft of the humerus that presented in our institution over a period of two years. The fracture pattern, treatment modality time to union and the number that needed operative fixation following a trial of conservative treatment was analysed. Of the 72 patients 4 were lost to follow-up. 45 patients had a 1.2.B or 1.2.C type of fracture and 23 had a 1.2.A type of fracture. 29 (41%) were successfully treated conservatively, 11 (16%) patients were operated as the primary procedure and 15 (22%) patients were operated due to delayed or non union. 13 (19%) patients were operated within 4 weeks of the fracture as their alignment was not acceptable on their weekly follow-up.

The average time to union in the patients treated conservatively was 22 weeks, while that of the patients treated primarily by open reduction and plating was 14 weeks (p-value<0.05). Patients who needed operation after initial conservative management required prolonged period of rehabilitation and union time was 32.2 weeks. At the time of fracture union 72% of the patients who had been treated conservatively had joint stiffness requiring physiotherapy, while only 18% of those who had an open reduction and internal fixation had stiffness and required physiotherapy. (p-value < 0.05).

In conclusion careful consideration should be given before it is decided to treat this fracture conservatively especially in the case of 1.2.A fracture pattern.