The purpose of this study was to investigate the mechanism of injury causing anterior cruciate ligament ruptures in snowboarders and skateboarders.

Knee injuries in snowboarding and skateboarding are rare. We have seen 22 ACL ruptures with an identical injury mechanism that has not been previously described. Fifteen ACL ruptures occurred in snow-boarders and 7 in skateboarders. All were advanced or expert boarders. All injuries occurred on landing a high jump, which resulted in significant knee compression. All described a flat landing on a flexed knee with no twisting component.

We postulate that anterior cruciate ligament rupture in these patients is due to explosive eccentric quadriceps contraction when landing from a jump. The injury mechanism is not boot induced as has been described in downhill skiers landing from a jump.

Aim: To investigate the efficacy of the Insall tube realignment procedure when used to treat osteoarthrosis of the lateral facet of the patello-femoral joint. This procedure has not been reported before for this indication.

Methods: The operation is a quadricepsplasty that tilts the patella to enable it to articulate on its intact medial facet, decreasing the loading of the damaged lateral surface. An independent retrospective review was performed with clinical examinations and a score of pain and activity. The mean period of follow-up was 3.6 years with a minimum of one year.

Results: There were 43 operations in 30 patients (12 males), with a mean age of 54 years. The patients graded their overall pain relief and functional change as being good to excellent in 32 knees, unchanged in four knees and worse in seven knees. The overall pre- and postoperative pain scores for sitting, walking, running and stair climbing all showed improvements. Ten patients felt some quadriceps weakness on descending stairs, but only one was clinically weak. There was an increase in the number of patients with severe pain on kneeling. Three patients with unsuspected tibio-femoral degenerative change seen at surgery all had poor results.

Discussion: We recommend this relatively simple and effective operation for the surgical treatment of isolated lateral facet patello-femoral osteoarthritis.