How are cystic lesions of the knee excised?

Updated: Dec 29, 2018
  • Author: David M Gonzalez, MD, FACS; Chief Editor: Thomas M DeBerardino, MD  more...
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Intraoperative details are dependent on the location of the cyst being treated. A prepatellar-infected bursitis is approached through a midline incision. Then, the contents of the bursa are evacuated, and all loculations are lysed. After thorough irrigation and debridement, the wound is packed open and allowed to drain. Appropriate antibiotics are begun, and the wound is readdressed in 2 to 3 days.

A popliteal or Baker cyst can be approached in a number of different ways. One way is to place the patient supine with the knee slightly flexed on the operating table. A lazy-S skin incision is made in the popliteal fossa. The cyst can usually be seen beneath the deep fascia and presents itself between the medial head of the gastrocnemius and the semimembranosus. The cyst is dissected by means of sharp and blunt dissection until its communication with a capsule is seen. The base is excised, and the defect is usually closed.

A study by Yang et al in 76 patients with popliteal cysts reported significantly better outcomes with arthroscopic internal drainage of the cysts, compared with open excision after arthroscopic treatment or open excision. Length of incision (1.6 ± 0.1 cm), incision healing rate (100%), postoperative visual analog score (VAS) for pain (2.7 ± 1.2), hospitalization time (7.8 ± 2.8 days), and Lysholm score at the final follow-up visit (85.8 ± 5.2) all were superior and the recurrence rate was significantly lower with either arthroscopic approach than with open excision only. [28]

Brazier et al provide a step-by-step description of arthroscopic treatment of popliteal cysts. These authors use an arthroscopic approach through a posteromedial portal to decompress the popliteal cyst and take down the posterior transverse synovial infold, a valve-type structure that permits one-way flow of synovial fluid into the cyst. Their operative approach is guided by preoperative knee MRI, which determines the exact location of the cyst. [29]  

Other cysts related to bursitis, such as medial gastrocnemius bursitis and semimembranosus bursitis, are treated in a similar fashion. Depending on the exact location, other approaches can be used, such as the medial hockey-stick incision with the knee flexed at 90°. Basic knowledge of the surgical approaches to the anterior, medial, lateral, and posterior aspects of the knee can serve the surgeon well in approaching any cyst about the knee. [30]

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