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Abstract & Commentary
Synopsis: In anterior cruciate ligament reconstruction, the best results regarding terminal extension postoperatively are obtained in those patients who have full extension prior to surgery.
Source: McHugh MP, et al. Preoperative indicators of motion loss and weakness following anterior cruciate ligament reconstruction. J Orthop Sports Phys Ther 1998;27(6):407-411.
Preoperative loss of motion has been implicated as a possible contributing factor to postoperative arthrofibrosis. It has also been associated with other postsurgical complications such as patellofemoral problems. The purpose of this study was to "1) determine what degree of preoperative motion loss represents a risk for postoperative motion problems; and 2) if preoperative weakness affects return to strength following surgery." McHugh and colleagues took measurements on 102 patients (56 men and 46 women; mean age, 31 ± 1 year). Autogenous bone-patellar tendon-bone graft was used on 96 patients, patellar tendon allograft on four patients, and semitendonosus-gracilis graft on two patients. Measurements were taken two weeks prior to anterior cruciate ligament (ACL) reconstruction and repeated six months following surgery. The time from injury to surgery was also documented: 58 of the patients had acute injuries (surgery £ 2 months from injury), 13 of the patients had subacute injuries (2-6 months since injury), and 31 patients had chronic injuries (surgery ³ 6 months from injury). Range of motion measurements were taken with the goniometer (no reliability of examiner reported) and knee extension strength was isokinetically measured . For analysis of range of motion measures, subjects were divided into three groups: Group 1 (patients who had equal extension bi-laterally [n = 42]), Group 2 (patients who lacked 1-4° of extension preoperatively in the involved site [n = 20]), and Group 3 (patients who lacked 5° or more of extension preoperatively [n = 42]). It was determined from Fisher’s Exact test that Group 1 was significantly different than Groups 2 and 3. In other words, having 5° loss of motion preoperatively did not increase someone’s risk any greater than loss of 1° preoperatively. In addition, patients with acute injuries had significantly greater loss of extension preoperatively than patients with chronic injuries, but the groups were not different six months postoperatively with respect to range of motion. With regard to strength measures, there was a significant difference in strength preoperatively and six months postoperatively (postoperative was stronger). However, across the three groups (based on chronicity), there was no difference in the groups with regard to postoperative strength.
Comment by Clayton f. Holmes, edd, pt, atc
This study attempted to evaluate the effect of loss of motion and strength preoperatively on postoperative loss of knee extension and postoperative loss of strength. Essentially, the findings of McHugh et al are as follows: "If the patient has loss of strength preoperatively, this cannot predict loss of strength postoperatively. If the patient loses range of motion preoperatively, that increases their chances for postoperative complications relative to loss of knee motion." The most important weakness of this study is the lack of examiner reliability relative to the goniometry. Because of the nature of goniometry, the examiner should establish reliability prior to use in data collection. The most important finding confirms the conclusions of Cosgarea1 and others who have stated that for best results regarding terminal extension post surgery, a patient should have full extension prior to surgery. This axiom holds true for range of motion but not necessarily strength. Future studies should look at regression models to evaluate the prediction of postoperative complications from preoperative variables.
1. Cosgarea AJ, et al. Prevention of arthrofibrosis after anterior cruciate ligament reconstruction using the central third patellar tendon autograft. Am J Sports Med 1995;23(1):87-92.