Does chondrocalcinosis affect Knee Society scores and range of motion after TKA?

BACKGROUND: Chondrocalcinosis is manifested by crystalline deposits of calcium commonly found during primary TKA for osteoarthritis. Its frequency among patients undergoing TKA is poorly defined, as is its influence on pain or function after TKA.

QUESTIONS/PURPOSES: The purposes of this study are to (1) determine the prevalence of chondrocalcinosis in patients undergoing TKA for osteoarthritis; (2) evaluate the effect of chondrocalcinosis on ROM and The Knee Society scores; (3) determine if patients with chondrocalcinosis and severe synovitis who underwent synovectomy are at risk for lower postoperative Knee Society scores and less ROM; and (4) assess if chondrocalcinosis is associated with increased rates of revision surgery.

METHODS: We retrospectively reviewed the medical records of 1500 primary TKAs performed by one surgeon. The minimum followup for patients was 24 months (average, 57 months; range, 24-120 months). There were 511 men and 934 women with an average age of 70 years. Fifty-five patients underwent bilateral knee replacements. Crystal deposition was graded prospectively during surgery using a subjective visual scale. A thorough synovectomy was performed on patients with severe synovitis and apparent crystalline deposition suggestive of calcium pyrophosphate dihydrate (CPPD) deposition (n = 50). The Knee Society scores, ROM, and revision rates were compared between patients with visible chondrocalcinosis with those without and between patients with mild chondrocalcinosis with those with severe chondrocalcinosis.

RESULTS: Chondrocalcinosis was found in 173 male patients (34%) undergoing TKAs during this period compared with 224 female patients (24%) (p < 0.001). The Knee Society scores for knee rating and function were similar in patients with or without chondrocalcinosis undergoing TKA. However, patients with visible CPPD deposition who underwent synovectomy for proliferative synovitis had diminished final ROM and Knee Society knee rating scores (107(o) versus 115(o) knee flexion, p < 0.001 and 87 versus 94 points, p = 0.001). We cannot determine whether this result is because of the synovectomy or severity of the disease, and therefore we cannot recommend a synovectomy at this time. Revision rates were no different among patients with chondrocalcinosis compared with those without it (3.6% versus 2.2%, p = 0.2).

CONCLUSIONS: Chondrocalcinosis is common among patients undergoing TKA for osteoarthritis. The presence of CPPD deposition does not appear to affect the ROM and Knee Society scores of patients with CPPD but without severe synovitis. However, patients with severe synovitis and visible CPPD who underwent thorough synovectomy may be at risk for having decreased postoperative ROM and pain develop.

LEVEL OF EVIDENCE: Level III, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.