Reconstruction of the anterior cruciate ligament (ACL) of the knee is a common surgery. One of the reasons for ACL reconstruction is to prevent the development of osteoarthritis (OA) of the knee. In an attempt to fix the ligament, though, OA can sometimes develop where the patella (kneecap) and femur (thigh bone) meet. This joint is called the patellofemoral joint.
The authors of this study followed up on 100 patients who had undergone ACL reconstruction surgery about seven years earlier. All patients had a follow-up physical examination, answered questions about their pain and function, and had knee X-rays taken. These latest results were compared with the patients’ records from before and just after surgery.
Of the 100 patients, follow-up X-rays showed that 53% had no sign of OA. Of the remaining patients, almost half ended up with some amount of degeneration. Mild degeneration was seen in 34%. Another 12% had moderate degeneration, and 1% had severe degenerative changes. Not everyone who had signs of OA felt pain or significant symptoms, however.
The X-rays showed a link between patellofemoral OA and a shortened patellar tendon. The worse the OA, the shorter the patellar tendon. The authors suggest the two may go hand-in-hand. There also tended to be a connection between patellofemoral OA and the spot where the tendon graft was placed. The incidence of OA was higher when the graft was placed slightly forward on the femur and further back on the tibia.
It is impossible to tell from this study how much the original knee injury, the type of surgery, or immobilization after surgery affected the development of OA. It is possible that newer surgical techniques using the arthroscope could show a lower rate of post-surgical OA in the patellofemoral joint. Patients usually don’t immobilize their knees during rehabilitation anymore, either. This study can help give a baseline to see if newer techniques are any better at preventing the “seven-year hitch” of post-operative OA in patellofemoral joint.