The evaluation and treatment of arthritis should include a comprehensive evaluation including multiple clinical and patient-specific factors. Medical history, age, body mass index (BMI), current functional level, and patient expectations and goals must be considered when counseling patients. Prior injury, a history of surgery and radiographic appearance will also guide treatment, as the location, size, and chronicity of cartilage defects, as well as the degree of underlying degenerative joint disease, may exclude some treatments. If an osseous procedure such as high tibial osteotomy (HTO) is planned, diffuse disease is a contraindication, and bone quality must also be considered, as it may be challenging to obtain robust fixation in patients with osteoporosis and other diseases that affect bone density and quality. Consideration must also be given to other risk factors for failure, including smoking, corticosteroid dependency, chronic illness, immunosuppressants, etc.

Conservative treatment of osteoarthritis of the knee encompasses a broad spectrum of modalities and pharmaceuticals. Before considering surgical intervention, many patients are offered conservative therapies as a means to delay invasive procedures. Often, multiple modalities are used in concert to maximize benefit. These treatments can provide symptomatic relief as well as alter the knee environment to attempt to limit the progression of the disease. Conservative possibilities include nonsteroidal anti-inflammatory drugs (NSAIDs), cyclooxygenase-2 (COX-2) inhibitors, steroid injections, viscosupplementation, bracing and other orthoses, physical therapy and other exercise, and weight loss.

The role of arthroscopy in the treatment of osteoarthritis of the knee remains controversial (18). Fifty percent or more of patients who undergo arthroscopy for osteoarthritis will report symptomatic relief (32). However, other studies have shown that only 44% of patients maintain decreased pain scores at 2-year follow-up (33), and up to 18% of patients undergo TKA within 3 years (34). Despite these findings, arthroscopic debridement remains a commonly performed procedure for osteoarthritis, and generalizability of the literature is limited by the heterogeneity of patient populations in these studies (18).

Several more recent randomized trials, however, have challenged the role of arthroscopic debridement in the treatment of osteoarthritis. In a randomized, controlled trial comparing arthroscopic lavage, debridement, or placebo surgery, Moseley et al. (32) evaluated 180 male veterans for a mean of 2 years following arthroscopy for treatment of osteoarthritis. Throughout the 2-year follow-up period, there were no statistically significant changes in pain scores among the three groups, leading the authors to conclude that the beneficial results of arthroscopy were no better than placebo in this homogenous patient population. In a subsequent study of a civilian population with moderate-to-severe osteoarthritis, Kirkley et al. (35) randomized 188 patients to either surgical debridement with medical/physical therapy or medical/physical therapy in isolation. At 2-year follow-up, there were no differences in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) or Short Form-36 (SF-36) scores between the two groups. The authors concluded that arthroscopic debridement was no better than optimized medical/physical therapy.

These randomized studies, however, largely excluded patients with large meniscal tears or mechanical symptoms, suggesting that some subpopulations of patients, particularly those with mechanical symptoms from degenerative meniscal pathology, would benefit from arthroscopy. For example, in a study of 68 patients with Outerbridge grade IV osteoarthritis and a medial meniscal tear, up to 82% of patients reported a reduction of pain at 52 months after debridement, with 75% of patients requiring no further surgery up to 75 months after arthroscopy (36). Other authors have shown that up to 81% of patients with advanced arthritis might benefit from aggressive arthroscopic lysis of adhesions to increase joint volume and thereby decrease joint reactive forces (37). Despite these findings, however, other studies have demonstrated difficulty predicting which patients might benefit from arthroscopic debridement (33, 38). Dervin et al. (33) evaluated 126 patients with primary osteoarthritis who had failed initial medical management. Unstable chondral flaps and meniscal tears were addressed at the time of arthroscopy. Only 44% of patients maintained decreased WOMAC scores at 2 years. However, the presence of medial joint line tenderness preoperatively coupled with the debridement of a corresponding meniscal tear at the time of surgery seemed to portend better outcomes. Despite this, the authors concluded that physicians were unable to reliably predict which patients would benefit from surgery, based on preoperative clinical findings.

The role of arthroscopy in physiologically young patients with osteoarthritis is also unclear. The AAOS clinical practice guideline for treatment of osteoarthritis of the knee recommends against routine arthroscopy with debridement/lavage in patients with primary osteoarthritis (3). However, a corollary to this stipulation specifies that this recommendation does not apply to patients with a primary diagnosis of meniscal tear, loose body, or other mechanical symptoms in the setting of concomitant osteoarthritis. In the absence of specific studies targeting these subgroups, clinical judgment and proper patient selection are critical for surgical decision making. Younger patients with mechanical symptoms and less severe disease are the most likely to benefit from a trial of arthroscopy. It is important, however, to have a candid discussion regarding expectations, cautioning patients that any postoperative gains may be of limited benefit.

For more than 50 years, HTO and distal femoral osteotomy (DFO) have been used for correction of lower extremity malalignment and alleviation of unilateral compartment gonarthrosis (39, 40). Lower extremity alignment has been shown to be a significant factor in the progression of osteoarthritis of the knee (41). Coventry (42) initially defined indications for HTO and suggested that the optimal candidate was relatively active, with a stable knee, good range of motion, localized (unicompartmental) osteoarthritis, and age less than 65 years. Due to concomitant surgical procedures, contemporary indications for HTO have expanded to encompass coronal and sagittal malalignment, unicompartmental overload with prearthritic change, anteroposterior and varus/valgus instability, lateral or hyperextension thrust from posterolateral instability, and ligamentous deficiency (43, 44, 45, 46 and 47). Osteotomies are also commonly used for limb realignment in concert with meniscal transplantation or articular resurfacing procedures (48, 49, 50 and 51). The medial compartment is the most common site of deformity in both primary knee osteoarthritis and secondary arthritis resulting from osteochondral lesions, postmeniscectomy change, or chronic anterior cruciate ligament (ACL) deficiency. The lateral compartment can also be involved,
often in concert with a valgus deformity, particularly in the context of lateral meniscal deficiency, as the lateral compartment is highly reliant on meniscal integrity to avoid overload and secondary osteoarthritis. Varus deformity is usually secondary to proximal tibia vara, and is best addressed with HTO. Valgus deformity of the knee is usually secondary to deformity of the distal femur, and therefore DFO is often more appropriate.