gms | German Medical Science

Objectives: Baker's cysts are not uncommon in patients eligible for total knee arthroplasty (TKA). There is a paucity of medium-term studies that assess the natural course of Baker's cyst following TKA. In this study, we report the one and five year outcome of patients to elucidate the state of their Baker's cyst following TKA.

Methods: In this prospective case series, 102 TKA patients were included. All patients were operated for primary osteoarthritis and preoperatively presented with a Baker's cyst. Sonography was performed to evaluate the existence and the gross size of the cyst before TKA, and at one and five years after TKA. Symptoms potentially attributable to the Baker's cyst were recorded at each assessment. In addition, the five year assessment included a sonographic assessment of the anterior aspect of the knee to identify joint effusion.

Results and conclusion: Ninety-one patients were available for the five year assessment. After one and five years, a Baker's cyst was still present in 87 (85.3%) and 30 (33.0%) patients, respectively. The mean preoperative cyst size was 14.5 cm2. At one and five years postoperatively, the mean cyst size was 10.6 cm2 and 9.9 cm2, respectively.

The probability of going into remission was dependent on the size of the Baker's cyst at baseline. Thirty-two patients (36.8%) who presented with a Baker's cyst at the one year follow-up had popliteal symptoms; at five years, 17 patients (56.7%) were symptomatic. At five years, no association between cyst size and popliteal symptoms was found.

Five years after the index procedure, the majority of the Baker's cysts that were present at baseline had gone into remission. The probability of going into remission was dependent on the size of the Baker's cysts at baseline.