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Surgeons and Patients Don't Always Agree on Results of Knee Surgery

Young athletes (children and teens) who have stabilization surgery for repeated dislocations of the patella (knee cap) have a 93 per cent success rate following the procedure. "Success" means their pain is less and their function is better. Yet when surveyed, these same patients report a much lower subjective (opinion) level of satisfaction. This study is another one to show a "disconnect" between surgical success and patient's perception of the results.

Let's take a closer look. One surgeon performed a patellar realignment procedure on 27 knees. The 24 children and teens in the study were between the ages of eight and 18. They all had at least two (but often more than two) patellar dislocations or subluxations (partial dislocation). They did not respond to conservative (nonoperative) care, which is the usual first-line of treatment for this problem.

The stabilization procedure varies from patient-to-patient. Age, skeletal maturity, and etiology (cause) are important factors in the decision-making process. The surgeon also performs an arthroscopic exam before doing surgery in order to find out what the patellofemoral joint looks like inside. Any unknown or previously unseen problems with the soft tissue structures and joint surface are identified.

The surgeon may perform a lateral release (cuts the soft tissue along the outside edge of the patella) with or without retensioning the medial soft tissue (changing the tension on the other side of the patella closest to the other knee). Other options include an osteotomy (the surgeon removes a wedge of bone to change knee alignment), repair of any damaged patellar ligaments, or a patellar tendon transfer (changes the angle of pull on the patella).

The work may be done from above or below the knee to create the stability needed based on the cause of the problem. In some cases, the patella is reshaped by doing a patellar shaving procedure. Any loose pieces of bone or cartilage found in the joint are removed as well. Most of the children (78 per cent) had more than one thing done during the same surgery -- referred to as combined procedures.

Why did patients with an apparent "successful" surgery still report dissatisfaction with the results? Could it be the measures used (standard tests of knee function, symptoms, and activity levels) don't fit this group? The authors suggest that microscopic damage to the joint and osteoarthritic changes might have something to do with patients' sense that the knee isn't stable.

They did find that the younger age groups and patients who had the surgery sooner than later had better outcomes. Those particular outcomes have led the surgeon to recommend patellofemoral reconstruction after only 2 subluxation or dislocation episodes -- rather than waiting until the child has had many more than that months to years after the first episode.

There was one other observation that surprised the surgeon: children who had subluxations (partial dislocation) rather than full dislocations actually had worse results. Logically, it would seem than a milder injury would lend itself toward a better final outcome. But that wasn't the case. So, why not?

The answer is not clear but there are some possible ideas. Perhaps the milder symptoms that accompany subluxations results in more frequent episodes that the patient fails to remember and report. Recovery is often faster with subluxations but damage at the microscopic level may be worse than realized.

And this all ties in with why patients don't necessarily come back to the surgeon and report dissatisfaction. But when asked by telephone survey later, they do report more problems than the surgeon realized when counting up the number of "successful" procedures. Dislocations don't occur but mechanical symptoms (e.g., pain with movement) are present and activity level is less than expected.

In summary, the study presented here confirms findings from other studies: patients do not always view their surgical results as successful. But they do not return to the surgeon and report ongoing symptoms or problems. When knee assessment tools like the International Knee Documentation Committee (IKDC) or the Lysholm score are used to measure outcomes, the results look good on paper but do not always provide an accurate view of the patient's response. More studies are needed to understand all the reasons for less than optimal outcomes reported following patellar realignment surgery.

Reference: Scott J. Luhmann, MD, et al. Outcomes After Patellar Realignment Surgery for Recurrent Patellar Instability Dislocations: A Minimum 3-Year Follow-Up Study of Children and Adolescents. In The Journal of Pediatric Orthopaedics. January/February 2011. Vol. 31. No. 1. Pp. 65-71.