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Intra-articular ganglion cysts in the knee large enough to cause neurovascular claudication are rare entities only identified in singular case reports. The severity of claudication can cause debilitating symptoms and pain to previously highly functional and asymptomatic patients. Total knee arthroplasty has been described to treat these cysts in elderly patients with osteoarthritis, although this treatment pathway may not appeal to patients without antecedent pain and high activity levels. This surgical report will detail a reproducible method of arthroscopic decompression of posterior, intra-articular cysts to relieve vascular claudication by highlighting technical pearls in navigating posterior knee arthroscopy.
The patient is a 65-year-old man with vascular claudication caused by a large posterior knee cyst compression the neurovascular bundle. Due to the severity of his symptoms, he was taken to the operating room and standard diagnostic arthroscopy was performed from the anterolateral and anteromedial portals. To appropriately access the posterior compartment in this patient with early arthritis, a burr was introduced from the anteromedial portal to partially debride the medial tibial spine and medial femoral condyle osteophytes. Next, the 30° arthroscope was introduced through a transpatellar Gilquist portal to visualize the posterior compartment. Under transillumination, a posteromedial portal was created and a cannula was placed. A 4.0-mm shaver was introduced from the posteromedial portal and the cyst walls were debrided until yellow, viscous, cystic fluid was expressed. A 70° arthroscope was then introduced into the Gilquist portal and digital compression of the cyst aided in decompression. A grasper was placed into the posteromedial portal to sample tissue for pathology. Finally, the 70° arthroscope was introduced into the posteromedial cannula and driven directly into the cyst to visualize complete decompression. Postoperatively, the patient’s vascular examination and ankle–brachial index were restored to his contralateral levels with resolution of his claudication symptoms and augmented range of motion.
Technique Video
See video under supplementary data.
Cystic degeneration of the anterior and posterior cruciate ligaments is a rare occurrence that most frequently presents with pain, fullness, and a flexion contracture.
Symptomatic posterior cruciate ganglion cyst causing impingement between posterior root of the medial meniscus and anterior to the posterior cruciate ligament.
While the etiology can be traumatic or idiopathic, arthroscopic resection of symptomatic patients has been demonstrated to be efficacious with low recurrence.
we describe the technique used to successfully treat a cyst causing vascular claudication in a patient with joint-space narrowing and severe claudication.
Patient Evaluation, Imaging, and Indications
The beginning of patient evaluation should begin with a thorough history, assessing the timeline and progression of clinical claudication and neurovascular symptoms. A physical examination specifically focusing on neurovascular function should be completed before the obtainment of bilateral ankle–brachial indices. If an abnormal ankle–brachial index is measured, further vascular studies including arterial Doppler examination should be procured. MRI of the knee must be completed to evaluate the location of the lesion to aid in preoperative planning in addition to characterizing the lesion to rule out malignant morphologies (Fig 1). Patients with suspicious-appearing oncologic masses must be then biopsied. Homogenous masses consistent with ganglion cysts in patients with severe claudication who have not responded to ultrasound-guided aspiration should then be indicated for operative resection and decompression.
Fig 1Magnetic resonance imaging of the right knee. Axial images above (A) and at the level (B) of the posterior cyst extending from the posterior cruciate ligament. The femur (F), tibia (T), cyst (C), and neurovascular bundle (arrow) are highlighted, with severe compression noted in (B).
The patient is placed supine for standard knee arthroscopy with a hip post and a foot roller to maintain approximately 90° of knee flexion, without the application of a tourniquet (Table 1). A standard 30°arthroscope (Stryker, Kalamazoo, MI) is placed into the anterolateral portal just lateral to the patellar tendon and at the level of the inferior patella and diagnostic arthroscopy is performed. The anteromedial portal is established at the same height as the anterolateral portal, just medial to the patellar tendon.
Table 1Pearls and Pitfalls
Pearls
Pitfalls
Using a burr to debride osteophytes along the medial femoral condyle and tibial spine allows access to the posterior knee with arthritic changes
Establishing the posteromedial portal without transillumination may cause injury to the saphenous vein
The transpatellar Gilquist portal allows optimal visualization of the cyst walls to aid efficient and safe debridement from the posteromedial portal
Directing the shaver posteriorly without the knee in flexion increases risk of injury to the neurovascular bundle
Introduction of a 70° arthroscope dramatically improves visualization and can be driven into the cyst from the posteromedial cannula
Sole use of a 30° arthroscope may inhibit cyst wall resection and increase risk of recurrence
Manual palpation of the posterior cyst to aid intraarticular extrusion must be performed in 90° of knee flexion to minimize risk of injury to the neurovascular bundle
Due to medial tibial spine overgrowth and osteophytes along the medial femoral condyle (Fig 2), a burr is introduced from the anteromedial portal to allow access to the posterior knee (Fig 3). After debridement of the osteophytes and partial resection of the medial tibial spine, a transpatellar Gilquist portal is created to access the posterior knee to optimize visualization.
Fig 2Viewing a right knee arthroscopy from the anterolateral portal, the hypertrophied medial tibial spine (TS) and medial femoral condyle (black arrow) are present, obstructing access to the posterior knee.
Fig 3Viewing a right knee arthroscopy from the anterolateral portal using a 5.0-mm burr (∗) to debride the medial tibial spine (TS) overgrowth and medial femoral condyle (MFC) osteophytes to provide posterior compartment access via the Gilquist portal.
After the arthroscope is transferred to the Gilquist portal, needle localization is performed to create a posteromedial portal. By transilluminating the posteromedial knee, the saphenous nerve and vein is avoided as the needle enters the knee joint from just proximal and posterior to the tibiofemoral joint. A No. 11 scalpel follows the needle into the joint, after which an 8.25-mm cannula is inserted into the posteromedial portal (Arthrex, Naples, FL).
After a cannula is placed into the posteromedial portal, a 4.0-mm oscillating shaver (Stryker) is introduced to debride fibrous tissue and the walls of the cyst (Fig 4). The highly viscous, straw-colored fluid and cyst walls are resected with digital palpation of the posterior knee used to further assist with the knee at 90° flexion to maximally distance the neurovascular bundle from the posterior capsule. Samples of this tissue are retrieved and sent to pathology (Fig 5). To better visualize the cyst and ensure that all walls are systematically debrided, the arthroscope is introduced into the posterior portal and the shaver is placed into the Gilquist portal.
Fig 4Viewing the right knee posterior compartment using a 30° arthroscope from the Gilquist portal, the cyst (C) is decompressed with a 4.0-mm shaver (S) introduced from the posteromedial cannula.
Fig 5Using the 70° arthroscope into the patient’s right knee from the Gilquist portal, an arthroscopic grasper (G) is introduced from the posteromedial cannula to sample tissue of the cystic walls (CW) to send to pathology.
Next, a 70° arthroscope is then introduced into the Gilquist portal and the cyst walls are thoroughly debrided, with the shaver returning to the posteromedial portal. Finally, the 70° arthroscope is driven directly into the cyst from the posteromedial portal to ensure circumferential decompression of the cyst (Fig 6). The wounds are closed with 3.0 nylon sutures and a sterile dressing is applied. An overview of this technique is displayed in Video 1.
Fig 6In the patient’s right knee, a 70° arthroscope from the posteromedial cannula is driven directly into the cyst viewing the lateral wall (black arrow) and the posterior wall (blue arrow) to ensure that all loose bodies and cystic fluid are thoroughly decompressed, thus completing the surgery.
Immediately following decompression, a neurovascular examination should be conducted in the recovery unit. Postoperatively, patients should be placed in partial weight-bearing status to allow a mostly elderly population the ability to ambulate while still modulating pain. Following 2 weeks, patients can be advanced to weight-bearing as tolerated. Range of motion should not be limited at any time point to optimize the recovery and maximize functionality.
Discussion
Ganglion cysts of the posterior cruciate ligament are extremely rare entities that can be successfully treated with arthroscopic resection.
Clinical suspicion of patients with pain, fullness, and flexion contractures leads to confirmation with MRI and subsequent surgical resection. Surgical treatment of large cysts causing vascular claudication, however, is even more uncommon and unstudied in the orthopaedic literature.
While nonoperative treatment is always offered to less-symptomatic patients, claudication necessitates a more urgent treatment paradigm. The standard initial treatments of knee cysts with observation, corticosteroid injections, and physical therapy will not address the claudication and the cysts are so viscous that serial aspiration is rendered ineffective.
In this technique, we present a reliable and safe surgical approach to decompression a posterior, intra-articular cyst that is causing severe claudication. While arthroscopic access to the posterior knee has been described,
efficacious decompression a cyst causing claudication in an arthritic knee are presented here and summarized in Table 1.
While more invasive surgery, including total knee arthroplasty, may be offered in the treatment paradigm, this treatment is excessively invasive for patients who were asymptomatic before rapid cyst development. The minimally invasive arthroscopic decompression allows for alleviation of claudication and vascular compression while offering a rapidly accelerated recovery and much fewer complications. Arthroscopic decompression of cysts carries the inherent risk of cyst reformation, and patients must be counseled regarding this complication. In addition, given the proximity of the neurovascular bundle to the posterior knee, inherent risk exists in surgical decompression. By carefully establishing a posteromedial portal and thoroughly evaluating preoperative imaging, risk can be minimized. Table 2 further delineates the advantages and disadvantages of the described approach. In conclusion, decompression of a posterior cyst causing neurovascular claudication can be safely and reliably accomplished by adhering to the principles outlined in this technique.
Table 2Advantages and Disadvantages
Advantages
Disadvantages
Excellent visualization and access of the cyst to thoroughly debride and decompress
Establishment of the transpatellar portal may result in iatrogenic damage to the tendon
Immediate relief of vascular claudication with accelerated rehabilitation without TKA complications
Surgeon must be comfortable with posterior knee anatomy and arthroscopy to minimize neurovascular risk
The patient is a 65-year-old man with vascular claudication caused by a large posterior knee cyst compression the neurovascular bundle. Due to the severity of his symptoms, he was taken to the operating room and standard diagnostic arthroscopy was performed from the anterolateral and anteromedial portals. To appropriately access the posterior compartment in this patient with early arthritis, a burr was introduced from the anteromedial portal to partially debride the medial tibial spine and medial femoral condyle osteophytes. Next, the 30° arthroscope was introduced through a transpatellar Gilquist portal to visualize the posterior compartment. Under transillumination, a posteromedial portal was created and a cannula was placed. A 4.0-mm shaver was introduced from the posteromedial portal and the cyst walls were debrided until yellow, viscous, cystic fluid was expressed. A 70° arthroscope was then introduced into the Gilquist portal and digital compression of the cyst aided in decompression. A grasper was placed into the posteromedial portal to sample tissue for pathology. Finally, the 70° arthroscope was introduced into the posteromedial cannula and driven directly into the cyst to visualize complete decompression. Postoperatively, the patient’s vascular examination and ankle–brachial index were restored to his contralateral levels with resolution of his claudication symptoms and augmented range of motion.
Symptomatic posterior cruciate ganglion cyst causing impingement between posterior root of the medial meniscus and anterior to the posterior cruciate ligament.
The authors report the following potential conflicts of interest or sources of funding: E.L. is a consultant for Moximed. N.C. is a consultant for Smith & Nephew. Full ICMJE author disclosure forms are available for this article online, as supplementary material.
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