Israel Medical Association Journal

Background: Injuries to the anterior cruciate ligament (ACL) are common and complete tears often fail to heal. ACL reconstruction is considered the surgical gold standard of care for ACL injuries in young active patients.

Objectives: To determine the corresponding morphological and histological features of the torn ACL in different time periods after injury.

Methods: The study included 28 remnant specimens of torn ACLs from patients who had ACL reconstruction surgery of the knee. The remnant pathology was evaluated by its morphology during arthroscopy and by histopathologic measurements.

Results: At surgery there were three progressive and distinct morphological tear patterns. The first pattern was noticed within the first 3 months from injury and showed no scar tissue. The second pattern appeared later and was characterized by the appearance of scar tissue with adhesion to the femoral wall. The third pattern was characterized by adhesion of the ACL remnant to the posterior cruciate ligament. The histological changes of the first morphological pattern showed abundance of blood vessels and lymphocytes at the torn femoral end with few irregular collagen fibers. The second and third tear patterns showed decrement in the number of blood vessels and lymphocytes with longitudinally oriented collagen fibers.

Conclusions: The morphological features of the ACL remnant in the first 3 months after injury showed no scar tissue and its histological features had the characteristics of a reparative phase. This phase was followed by a prolonged remodeling phase that ended with attachment of the remnant to the posterior cruciate ligament.

Background: Medical evaluation of a suspected meniscus injury begins with a history-taking and physical examination. Suspected meniscus injuries not responding to treatment are usually sent for imaging to confirm the diagnosis before arthroscopy. Tc-MDP bone single photon emission computed tomography (SPECT) scan has been suggested as an alternative to magnetic resonance imaging (MRI) in evaluating suspected knee meniscus tears.

Objectives: To examine the accuracy of knee SPECT as a tool to identify meniscus tears versus that of MRI as compared to the gold standard of arthroscopy.

Methods: The Israel Defense Forces database for 2005 through 2009 was searched according to the key words knee MRI, knee SPECT and knee arthroscopy. We identified 330 subjects who had undergone both a single knee SPECT and a single knee MRI prior to knee surgery. The medical files of 193 of the 330 subjects were randomly selected for review. A comparison was made between the preoperative SPECT and MRI studies and the arthroscopic finding. The sensitivity, specificity and accuracy were calculated.

Results: The subjects’ age was 21.3 ± 3.9. The agreement between SPECT and arthroscopy was 0.14 for the medial meniscus and 0.29 for the lateral meniscus. The agreement between MRI and arthroscopy was 0.59 for the medial meniscus and 0.69 for the lateral meniscus. SPECT scan was found to be 61% sensitive, 54% specific and 58% accurate in detecting common knee pathology, whereas MRI was found to be 95% sensitive, 67% specific and 85% accurate.

Conclusions: Knee SPECT has a lower sensitivity, specificity and accuracy than MRI in evaluating meniscal injuries and its use can result in increased unnecessary surgery.