by Edward G. McFarland, MD
Edward G. McFarland, MD, is director, sports medicine and shoulder surgery, department of orthopaedic surgery, Johns Hopkins University, Baltimore, Md.
With current technology, anterior cruciate ligament (ACL) reconstruction can successfully provide a patient with a stable knee for activities of daily living (ADL) and for athletic activities at all levels of participation. Chronic ACL deficiency with repetitive giving way can result in meniscal and chondral injury in many patients. However, ACL reconstruction is not indicated in every patient, depending upon their pathology and activity level. This uncertainty increases when discussing whether reconstruction is indicated in the "arthritic knee."
Multiple variables influence the decision-making, including the degree of arthritis, the degree of laxity, the presence and extent of meniscal pathology, other ligamentous abnormalities, extent of malalignment, patient activity level and patient expectations. ACL reconstruction in the arthritic knee must consider these variables, and should be performed with knowledge of its limitations in this setting.
ACL reconstruction is indicated in patients who experience giving way with activities, whether it be activities of daily living or sports. Most chronic ACL- deficient knees have some degree of mild arthritic changes, and in this patient population ACL reconstruction will eliminate instability and prevent further damage caused by subluxations. ACL reconstruction in this population will not reverse the degenerative changes nor prevent deterioration due to existing unrepairable meniscal damage. In almost every study of knees with ACL deficiency, patients with surgery and particularly those with meniscal pathology showed some degenerative changes at long-term follow-up. Patients with mild degenerative changes and meniscal damage should be warned that their knee is not normal and that there is a possibility their arthritis will progress, even if they have their ACL reconstructed.
Altered kinematics of the knee due to ACL deficiency has not been demonstrated by itself to be a significant cause of arthritis. Consequently, an ACL reconstruction should not be offered to patients based upon the unproven belief that it will restore normal kinematics to the knee and, therefore, prevent arthritis. Only one study with short-term follow-up has suggested that an ACL reconstruction may decrease pain and swelling in patients with mild arthritis, but no symptomatic giving away.5 With no control groups in that study, it is speculative that the reconstruction led to more normal kinematics in this population, and also it is unknown whether this had any long-term affect upon their activity level or degenerative changes.
In patients with ACL-deficient knees and more severe arthritis due to chronic meniscal pathology or to varus or valgus malalignment, the decision to perform ACL reconstruction becomes more difficult. In this population, pain and swelling is usually due to the arthritis. Instability symptoms may be due to the ACL deficiency or to flattening or irregularity of the articular surface. Several studies have noted the success of combined ACL reconstruction and upper tibial osteotomy (UTO) in this patient population.1,2,3,4 None of these studies has demonstrated that the combined operation was better than UTO alone. Only Noyes' study compared a group of patients with UTO alone to patients with combined UTO and ACL reconstruction, and there was no significant difference in relief of symptoms or return to athletics.4
Patients with ACL deficiency and severe medial arthritis (viz. double varus knee) may also have other pathologies of the posterolateral corner structures (viz. triple varus knee). Noyes, et al have demonstrated the complexity of this group using gait analysis.4 How these combined abnormalities can be addressed to affect long-term results of these procedures will hopefully be forthcoming. Unfortunately gait analysis continues to be expensive, technically demanding and not readily available to all surgeons.
Combined ACL reconstructions and UTO necessitate surgeons and staff who are adept at both procedures. Although the reported complication rates are low for these combined procedures, fixation of the osteotomy and ACL grafts must be secure to allow early motion yet prevent nonunion. These concerns have prompted some surgeons to stage these operations, and usually the osteotomy is performed first.1 There are no studies which provide data comparing staged vs. concomitant osteotomy and ACL reconstruction.
Combined ACL reconstruction and UTO has been described by almost every author as a salvage procedure intended to decrease symptoms and allow ADLs and some recreational sports. In every study of this combined approach the activity level of the patients either stayed the same or slightly decreased.1,4 ACL reconstruction, with or without a concomitant osteotomy, is not contraindicated in the patient with arthritis, but the patient and the surgeon need to have realistic expectations of the results.
In summary, ACL reconstructions will not reverse arthritic changes and will not prevent arthritis in patients with irreversible meniscal pathology. The hypothesis that ACL reconstruction is needed to restore more normal kinematics is unproven. ACL reconstruction in the severely arthritic knee, with or without osteotomy, should be viewed as a salvage operation, until technology gives us a better way to define the best operative candidate.