by Alan S. Curtis, MD
Alan S. Curtis, MD, is a clinical instructor of orthopaedic surgery, and director of the Bioskills Center at the New England Baptist Hospital, Boston.
Treating the anterior cruciate ligament (ACL) deficient knee continues to be a challenging problem for the orthopaedic surgeon. Endoscopic anterior cruciate ligament reconstruction combined with an accelerated rehabilitation program has decreased the overall morbidity of the procedure and made it more appealing to many patients. The decision on whether a patient will benefit from surgery remains complex due to the many variables involved, including age, activity, state of the menisci and presence or absence of osteoarthritis.
Buss and Warren reviewed a group of older and relatively inactive patients with ACL injuries. After four years of follow-up, they concluded that "non-operative management of anterior cruciate ligament injuries can yield satisfactory results provided that the patients are willing to accept a modest amount of instability and a slight risk of meniscal injury." At the other end of the spectrum is the young athlete with intact or repairable menisci who wishes to remain active, and is certainly best served by an early ACL reconstruction. The remaining cruciate deficient population falls somewhat into a gray area in which the decision to operate must be individualized in each case.
Perhaps the most challenging patient to treat and improve is the rather significant population of individuals with ACL deficiency who have had previous meniscectomies and are now going on to develop osteoarthritis. In the majority of cases these patients are far too young for knee replacement surgery and wish to remain as active as possible. The history in this patient group is often remarkably similar.
An initial knee injury in high school or college was treated for a short period of time with a brace. The initial symptoms resolved and this was followed by a period during which the knee functioned very well until a recurrent injury which required an arthroscopy and meniscectomy. From that point, the story is usually one of decreasing activity level, but continued or increasing symptoms.
Factor in income
There is significant evidence in the literature implicating meniscectomy as a primary factor in ACL deficient knees that have a poor outcome and early development of osteoarthritis. In the normal knee, the menisci transmit and disperse load but play a rather insignificant role in the stability of the knee. When the anterior cruciate ligament is torn the menisci become important secondary stabilizers of the knee, but are poorly suited for the task.
The repetitive forces of strenuous activities rapidly overload the capabilities of the meniscus leading to degeneration and tearing. The incidence of meniscal tears in the chronic ACL deficient knee increases with time to nearly 80 percent. Development of osteoarthritis in the cruciate- and meniscal- deficient knee may be inevitable. Satku noted an 11 percent incidence of osteoarthritis in long-term follow-up of anterior cruciate deficient knees with intact menisci. In those knees with cruciate tears and menisectomy the incidence rose to 100 percent over five years. Even with rim-preserving or partial meniscectomy, Neyret and Dujour reported a 65 percent incidence of osteoarthritis in the cruciate deficient knee with long term follow-up.
Noyes proposed a checklist to identify those patients at significant risk to develop early osteoarthritis as a result of an anterior cruciate ligament tear. Factors include pain and swelling with simple activities of daily living, meniscal loss, crepitus and varus alignment. In these patients, the best treatment is prevention and isometric anterior cruciate ligament reconstruction early in the course. The best treatment option for those patients with ongoing instability and symptomatic arthritic changes of their knee who wish to remain active is unclear.
It is important in these patients to understand the etiology of their often complex symptoms so that the treatment can be tailored accordingly. Regardless of what treatment option is chosen, expectations should be limited and activity modification is crucial to a good outcome. The goal of the work-up in these patients is to clarify whether the main complaints and objective findings are of instability, arthritis or both conditions. On examination, instability should be well-documented as well as the degree of joint line tenderness. In more advanced arthrosis there may be crepitus, varus stance and significant atrophy. Radiologically, it is important to look at full-length stance films to evaluate overall limb alignment.
Shelbourne reported on autogenous patellar tendon ACL reconstruction in patients with early symptomatic arthritis and noted significant subjective and objective improvement in 33 patients with 44-month follow-up. Their patient study group had a trial of preoperative bracing and noted improvement, even in those patients whose main complaint was more of pain. O'Brien reported on autogenous ACL reconstruction in the chronic ACL deficient knee and noted average post-op scores over 90 on the ligament rating scale. They did have a significant incidence of patella-femoral joint pain postoperatively, but felt this was due to prolonged immobilization.
At the New England Baptist Hospital, our group has used allograft in the degenerating knee with chronic instability and normal alignment. The goal of surgery in these patients was to restore an end point, eliminate the pivot shift and minimize the morbidity of the procedure. This group of patients is currently under study, but we are pleased with the initial results.
For those patients with malalignment, advanced arthrosis and instability, treatment options include osteotomy with or without a cruciate ligament reconstruction. The goal of surgery in this highly-select population is to restore alignment, unload the degenerative compartment, and, if needed, restore stability.
The surgical procedure of combined high tibial osteotomy and ACL reconstruction is technically demanding. The osteotomy is performed first to address alignment and, depending on the type of osteotomy chosen, collateral ligament laxity. Secure fixation of the osteotomy is important because this allows a normal anterior cruciate ligament rehabilitation program to be followed.
Results of combined anterior cruciate ligament-high tibial osteotomy procedures in the literature is sparse, but encouraging. O'Neill (10 patients), Noyes (16 patients), Neuschwander and Drez (5 patients), Dejour and Neyret (44 patients) and Minas (15 patients), all have reported good results with various techniques in short two-year follow-up. All authors have emphasized that this is a salvage procedure and expectations should be limited.
In conclusion, the best treatment of combined instability and arthritis may be prevention with early isometric reconstruction and meniscal-sparing surgery. Given the chronic situation, the treatment must be tailored to the individual patient's symptoms and anatomic findings. Combined osteotomy and ACL reconstruction is a viable option, but it must be stressed that this is a salvage situation and modification of activity is critical to an acceptable outcome.
Dr. Curtis and Edward G. McFarland, MD, who wrote the following article shared some of the same sources.