The literature is divided as to the necessity of an intact posterior cruciate 
ligament for functional stability. Presented here is a prospective study of 
isolated posterior cruciate injuries seen in the acute stage in 13 patients, 6 
males and 7 females. The diagnosis of posterior cruciate ligament tear was made 
clinically and confirmed by arthroscopy. The average age at injury was 22 years. 
The athletic activity at injury was varied. Hyperflexion was the most common 
mechanism of injury, followed by pretibial trauma in the hyperflexed knee or in 
the "dashboard" injury. There were seven complete midsubstance tears and five 
partial tears. Direct visualization of the posterior cruciate ligament was not 
attained in one patient. All patients were treated nonoperatively on a 
physiotherapy routine. Average followup was 2.6 years. Patients were clinically 
examined and subjected to KT-1000 and Cybex testing. All patients were able to 
return to their previous activity and experienced no limitations with their 
injured knees. Using Hughston's criteria, subjective and functional ratings were 
all good. However, only 3 rated good and 10 fair when assessed objectively. We 
conclude that acceptable functional stability in these patients does not 
necessarily require absolute static stability. Nonoperative treatment of the 
isolated posterior cruciate ligament midsubstance injury may be a viable 
alternative to the difficult repair/reconstruction procedure.