Knee replacements are great to have around but they don't last forever. Younger, active adults who experience degenerative arthritis of the knee may be too young for a knee replacement. It's likely they will outlive the implant. Getting a second knee replacement is not usually an option. So what can be done instead?
Anyone with chronic knee pain who has been evaluated by an orthopedic surgeon and diagnosed with early stages of degenerative arthritis can begin with conservative (nonoperative) care. Activities can be modified to reduce stress and load on the joint. Weight loss is advised for anyone who is overweight. Physical therapy to improve posture, alignment, motion, and strength is often helpful.
But when the joint is worn down to the end-stages of arthritis, then surgery is often required. In this study, one particular type of knee arthritis is investigated. Medial compartment osteoarthritis (MCOA) affects just one side of the joint -- medial refers to the side closest to the other knee.
Misalignment of the hip, knee, and/or ankle leading to an uneven weight distribution contributes to the development of medial compartment osteoarthritis (MCOA). Surgery to correct the problem consists of: high tibial osteotomy (HTO), unicompartmental knee arthroplasty (UKA), or total knee replacement (TKR).
One surgeon performed 455 high tibial osteotomies in patients with medial compartment osteoarthritis and then surveyed long-term results up to 19 years later. The results are the subject of this study. High-tibial osteotomy refers to a surgical procedure where the surgeon removes a wedge-shaped piece of bone from one side of the tibia (lower leg bone). The word "high" tells us the wedge is taken out of the tibia at the top of the bone near the knee (rather than down low by the ankle).
There are different ways to do a wedge osteotomy -- the bone can be removed from the medial side of the tibia or from the lateral side (opposite the medial side or the side away from the other knee). The patients in this study all had a high-tibial lateral closing osteotomy. You know that a high osteotomy refers to where the bone is removed from (upper part of the tibia).
You know that a lateral osteotomy is taken from the outside edge of the tibia. But what does a "closing" osteotomy mean? That's where the piece of bone is removed and the two remaining edges of bone are shifted together (the hole made by removing the bone is closed). The goal of a lateral open osteotomy for medial compartment osteoarthritis (MCOA) is to shift the weight off the medial side of the joint. By shifting the weight-bearing load, the medial joint surface gets a break and the tension on the knee ligaments can be corrected.
The surgeon who did the operations wanted to know several things: 1) did the procedure hold up over time? 2) what factors helped predict success or failure? and 3) were the patients satisfied enough that they would do it all over again if they had the chance?
In order to find out how everyone answered those questions, the patients were all contacted by phone and interviewed. Questions were asked about height and weight to calculate body mass index (BMI). The British Orthopaedic Association Patient Satisfaction Scale was given to each patient who participated. Function was assessed using the Oxford Knee Score and failure was determined by the need for further knee surgery.
What did they find out? Were there any surprises? First, a little bit about the patients. There were far more men in the study than women (3:1 ratio). Patients ranged in age from 24 to 70 years old. There were an equal number of right and left knees involved.
Complications included blood clots to the lungs, deep vein clots in the legs, hematoma (pocket of blood) pressing on a nerve, and bone nonunion. One-third of the group did have a second surgery -- either to revise the osteotomy or to replace the joint. But 85 per cent said they were satisfied with the results and would have the same procedure again if they had it to do all over again.
Further analysis of all the data collected showed there were some predictive factors for success -- in other words, patients with these particular characteristics were more likely to have better long-term survival of the joint. The three most significant predictive factors for success were lower body weight (BMI less than 25), younger age (less than 50 years old), and a weak or deficient anterior cruciate ligament (ACL).
A BMI greater than 25 signals overweight. Obesity is defined as a BMI greater than 30. For patients with a damaged, injured, or ruptured anterior cruciate ligament (ACL), the high-tibial osteotomy provided the stability needed to prevent further joint damage.
In summary, high-tibial osteotomy is an effective way to treat medial compartment osteoarthritis (MCOA) of the knee. Studies have shown that the joint cartilage that's worn down can regrow when pressure is eased off that area. Results do deteriorate over time but many patients buy as much as 15-years of time before needing a total knee replacement.
When you are under age 50, that's a pretty significant benefit of the procedure. Reduced pain, improved function, and better quality of life make this a viable treatment option for younger, more active adults who aren't quite ready for a knee replacement.
Reference: Catherine Hui, MD, FRCS(C), et al. Long-term Survival of High Tibial Osteotomy for Medical Compartment Osteoarthritis of the Knee. In The American Journal of Sports Medicine. January 2011. Vol. 39. No. 1. Pp. 64-70.