Abstract
Range of motion after total knee replacement is an important outcome variable. Motion impacts the patient’s ability to perform a variety of activities of daily living. In addition, a stiff knee is also a painful knee secondary to continuous soft tissue irritation. Appropriate knowledge in terms of variables that effect range of motion as well as evaluation of the stiff knee are therefore important in the practice of total knee arthroplasty.
The most important and consistent factor in determining postoperative flexion is preoperative flexion. Other factors that have been invariably associated with flexion after knee replacement include weight of the patient, age, preoperative diagnosis, and implant design. In terms of implant design, cruciate substituting designs have been reported in several studies to have better motion than cruciate retaining designs. Recent data also suggests that patients with a high visual analogue scale for pain also had poor range of motion following total knee replacement.
In analysing a patient with a stiff knee it is thus first important to try and determine what the patients preoperative range of motion was. This helps in determining what the biologic capacity for range of motion after knee replacement. Evaluation of the preoperative x-ray is important in determining factors such as elevation of the joint line and matching the tibial slope especially in cruciate retaining implants. Failure to appropriately match the patient’s tibial slope leads to a tight flexion gap and a decrease in flexion. Malrotation of the components and stuffing the patello-femoral compartment with a thick patellar reconstruction can also decrease postoperative flexion.
Balancing of the posterior cruciate ligament in cruciate retaining designs is obviously critical. It is difficult to tell based on physical examination whether the cruciate ligament is in fact tight as secondary contractures develop. If preoperative evaluation determines that the implants are well-positioned manipulation under anaesthesia is a viable option. In both cruciate retaining and posterior cruciate substituting designs this can be safely done up to three months after surgery. For patients who present late after total knee replacement with significant complaints of stiffness, an arthrotomy with debridement of the of the suprapatellar pouch, recreation of the medial and lateral gutters and resection of the posterior cruciate ligament can be successful. Finally implant revision is sometimes required.
The abstracts were prepared by Mrs Dorothy L. Granchi, Course Coordinator. Correspondence should be addressed to her at PMB 295, 8000 Plaza Boulevard, Mentor, Ohio 44060, USA.
