Knee Stability Following Anterior Cruciate Ligament Rupture and Surgery: The Contribution of Irreducible Tibial Subluxation

• Published in: Journal of bone and joint surgery. American volume Vol. 86; no. 5; pp. 983 - 987
• Main Authors: Almekinders, Louis C, Pandarinath, Rajeev, Rahusen, Frank T
• Format: Journal Article
• Language: English
• Published: Boston, MA Copyright by The Journal of Bone and Joint Surgery, Incorporated 01.05.2004; Journal of Bone and Joint Surgery Incorporated; Journal of Bone and Joint Surgery AMERICAN VOLUME
• Edition: American volume
• Subjects: Adult; Anterior Cruciate Ligament - surgery; Anterior Cruciate Ligament Injuries; Biological and medical sciences; Diseases of the osteoarticular system; Humans; Joint Instability - etiology; Knee Dislocation - surgery; Knee Joint - diagnostic imaging; Knee Joint - surgery; Medical sciences; Orthopedic Procedures - adverse effects; Osteoarthritis, Knee - etiology; Radiography; Retrospective Studies; Treatment Outcome; Knee; Human; Luxation; Stability; Treatment; Tibia; Surgery; Orthopedics; Diseases of the osteoarticular system; Rheumatology; Tissue rupture; Anterior cruciate ligament
• ISSN: 0021-9355; 1535-1386
• DOI: 10.2106/00004623-200405000-00014

BackgroundKnee stability after anterior cruciate ligament reconstruction is generally determined by measuring total anteroposterior tibial motion. In spite of a decrease in excessive anteroposterior tibial motion after anterior cruciate ligament reconstruction, problems can still develop. In the present study, we sought to define the tibiofemoral relationship more accurately with use of stress radiographs of human knees after anterior cruciate ligament rupture and after anterior cruciate ligament reconstruction.MethodsA previously described radiographic technique was used to evaluate the position of the tibia relative to the femur with the application of an anteriorly directed tibial force and subsequently with the application of a posteriorly directed tibial force. Tibial position and total tibial translation were calculated from these radiographs. In addition, KT-1000 measurements were obtained. Three groups of patients were studiedGroup 1 included twenty-eight patients with an untreated anterior cruciate ligament rupture, Group 2 included nineteen patients who had undergone a clinically successful anterior cruciate ligament reconstruction, and Group 3 included twenty-five control subjects with normal knees.ResultsKT-1000 testing showed that the average side-to-side differences in Group 1 (5.8 mm) and Group 2 (2.7 mm) were significantly different from that in Group 3 (0.8 mm) (p < 0.01 and p < 0.05, respectively). Stress radiographs showed that the average total tibial translation in Group 1 (9.8 mm) was significantly different from those in Group 2 (5.6 mm) and Group 3 (4.3 mm) (p < 0.05 and p < 0.001, respectively). Within Group 1, knees with radiographic signs of osteoarthritis were more stable, with an average total tibial excursion of 6.8 mm. The improved stability of the reconstructed knees in Group 2 and the osteoarthritic knees in Group 1 was not entirely the result of decreased anterior tibial translation; it was, in part, due to an irreducible anterior subluxation of the tibia. A posteriorly directed stress in these knees did not reduce the tibia to the anatomic position relative to the femur; the osteoarthritic knees in Group 1 were 9.9 mm short of full reduction and the knees in Group 2 were 3.1 mm short of full reduction (p < 0.01)ConclusionsIrreducible tibial subluxation can be present in the knee following surgical reconstruction of the anterior cruciate ligament. Osteoarthritic changes following an untreated anterior cruciate ligament rupture are also associated with uncorrectable tibial subluxation along with a decrease in instability. The irreducible tibial subluxation could explain why osteoarthritic changes still may develop in stable, reconstructed knees in spite of the improved stability. Currently used arthrometric measurements, such as KT-1000 scores, do not measure this phenomenon.Level of EvidenceTherapeutic study, Level III-2 (retrospective cohort study). See Instructions to Authors for a complete description of levels of evidence.