Acute hemarthrosis of the knee: Indications for diagnostic arthroscopy

Abstract

The objective of this study was to define the role of early diagnostic knee arthroscopy for patients with an acute knee injury and hemarthrosis. Forty-five patients with an acute knee injury followed by a posttraumatic hemarthrosis during a 1-year period were prospectively reviewed. All patients were evaluated preoperatively followed by examination under anesthesia and arthroscopy of the knee. The majority of patients, 32 (71%), had an anterior cruciate ligament tear. Meniscal tears occurred in 21 patients (47%). Meniscal tears requiring surgery occurred in only 10 of 25 meniscal tears (40%). Seven patients (16%) had medial collateral ligament and/or posteromedial capsular sprain. Eight patients (18%) had an osteochondral fracture or patellar dislocation associated with an osteochondral fracture. The majority of knees with a torn meniscus or osteochondral fracture had an anterior cruciate ligament tear. Clinically, 18 of 21 knees (86%) with an acute complete anterior cruciate ligament tear were diagnosed preoperatively with the Lachman test. The Lachman test conducted with patients under anesthesia was positive for 19 of 21 knees (90%) with an acute complete anterior cruciate ligament tear. The preoperative examination correctly identified six of seven knees (86%) with a medial collateral ligament sprain. The preoperative Lachman test was positive in only two of five knees (40%) with a partial anterior cruciate ligament tear. The Lachman test with patients under anesthesia was positive for four of five knees (80%) with an acute partial anterior cruciate ligament tear. Preoperative examination yielded the correct diagnosis in only 9 of 21 knees (43%) with a meniscal tear and 1 of 6 knees (17%) with an osteochondral fracture. Diagnostic arthroscopy for the evaluation of the acute knee injury with posttraumatic hemarthrosis is indicated when a partial anterior cruciate ligament tear is suspected, or for the evaluation of meniscal tears and osteochondral fractures associated with the complete anterior cruciate ligament tear. Diagnostic arthroscopy is not necessary to diagnose a complete anterior cruciate ligament tear if the Lachman test without patients under anesthesia is positive. For patients with a negative Lachman test without anesthesia, follow-up should be maintained because 14% of acute complete anterior cruciate ligament tears can be missed initially on examination without anesthesia. Diagnostic arthroscopy may not be indicated initially for a patient diagnosed with a complete anterior cruciate ligament tear, in the absence of mechanical symptoms such as locking or catching, provided the patient is to be managed conservatively.