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Dissecting a popliteal cyst after failed unicompartmental knee arthroplasty
Case Report
Dissecting a Popliteal Cyst After Failed Unicompartmental Knee Arthroplasty Kotaro Yamakado, M.D.
Abstract: This report documents the first case of a popliteal cyst in a knee with failed unicompartmental knee arthroplasty (UKA). The cyst was treated successfully with the creation of a small communication hole between the posteromedial compartment and the popliteal cyst under direct arthroscopic visualization. This was followed by the replacement of a worn polyethylene insert via a small arthrotomy. Three months later, the popliteal mass had disappeared. This case suggests that a dissecting popliteal cyst may occur after UKA as one of the signs of a malfunction. It also suggests that treatment should be directed toward the joint and not the cyst itself. Key Words: Dissecting popliteal cyst—Unicompartmental knee arthroplasty—Polyethylene—Wear.
D
issecting popliteal cysts, which were first described by Adams1 in 1840 and further studied by Baker2 in 1877, occur most frequently as a result of intra-articular knee pathology. A popliteal cyst following unicompartmental knee arthroplasty (UKA) has never been reported, although there are a few reports concerning dissecting popliteal cysts associated with total knee arthroplasty (TKA).3-6 The author reports the first case of a popliteal cyst that occurred in a knee with failed UKA and symptoms of calf pain and functional disability. CASE REPORT A 78-year-old woman had undergone UKA of the left knee with a Miller/Galante Unicompartmental Knee System (Zimmer, Warsaw, IN) for osteoarthro-
From the Department of Orthopaedics, Kahoku Central Hospital, Kahoku-gun, Ishikawa Prefecture, Japan. Address correspondence and reprint requests to Kotaro Yamakado, M.D., Kahoku Central Hospital, Ro 51-2, Tsubata, Tsubata-machi, Kahoku-gun, Ishikawa Prefecture, Japan 929-0300. E-mail: [email protected] © 2002 by the Arthroscopy Association of North America 0749-8063/02/1809-3458$35.00/0 doi:10.1053/jars.2002.36485
sis 8 years earlier. The postoperative alignment of the leg was satisfactory, and the femoral component was implanted properly. However, the tibial tray was implanted in the valgus position. The postoperative course was uneventful until 5 years after surgery. At this time, the patient began to develop pain and recurring popliteal swelling of the left knee (Fig 1). On physical examination, a tense palpable mass (7 ⫻ 7 cm) was found in the posteromedial aspect of the knee. The patient’s knee had full range of motion and no effusion of the joint was found, but there was a slight tenderness and local heat at the medial joint line. Neurovascular status was normal. Aspiration of the cyst showed 60 mL of red turbid fluid, and the cyst recurred within 24 hours. Microbiological culture of the sample was negative. Stress radiographs showed correctable varus deformity, suggesting wear of the polyethylene insert and the tibial metal tray. Radiographs of the cyst after injecting radiopaque material were consistent with a popliteal cyst but did not show intra-articular communication (Fig 2). Computed tomography (CT) after cystography revealed an extra-articular mass adjacent to the posterior joint capsule (Fig 3). Serum laboratory analyses (complete blood count, prothrombin time, activated partial thromboplastin time, erythrocyte sedi-
1024 Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 9 (November-December), 2002: pp 1024-1028
POPLITEAL CYST AFTER FAILED KNEE ARTHROPLASTY
FIGURE 1. cyst.
The left knee on initial presentation. Note the popliteal
mentation rate, and C-reactive protein) were within normal limits. The patient refused formal revision by means of conversion to TKA because she believed the prosthesis was functioning well. Therefore, we performed arthroscopic capsulotomy of the posteromedial compartment (creation of a small communication hole between the posteromedial compartment and the popliteal cyst) followed by revision arthroplasty with polyethylene replacement under regional anesthesia. Three portals—anterolateral, anteromedial, and posteromedial—were used. On initial examination, there was proliferation of the synovium, which was stained black with metal debris. Using a shaver, we debrided the debris from the infrapatellar area, tibiofemoral joint, and remaining areas of the intercondylar notch. After resection of the medial meniscus remnant, it was clearly shown that the centromedial part of the tibial polyethylene
1025
insert was worn down and that the tibial tray was exposed (Fig 4). After the anterior compartments were examined, a posteromedial surgical portal was created under direct visualization with a 70° arthroscope passed through the lateral surgical portal and into the posteromedial compartment via the intercondylar notch. The shaver was introduced through the posteromedial portal with visual access through the anterolateral portal. After synovectomy of the posterior compartment, the posterior capsule was passed cautiously with the shaver, as planned using preoperative CT. When the communication hole between the joint space and the cyst was created, the cutting edge of the shaver was turned to prevent contact with the vascular structure of the popliteal region. The capsular communication hole was enlarged with the punch and the retrocutting punch and the cyst was evacuated. At the end of the capsulotomy, there was a capsular opening of 20 to 25 mm in diameter (Fig 5). After completion of the arthroscopy, an anterior midline incision measuring approximately 4 cm was made through the previous scar. A severely worn polyethylene tibial insert was retrieved. The tibial metal tray and femoral component were stable without signs of loosening. A new polyethylene insert was introduced, and the incision was closed. The areas of polyethylene wear noted at revision reflected the valgus position of the tibial tray (centromedial point loading). Gait and daily activity was allowed on the first postoperative day. Three months later, the popliteal mass had disappeared (Fig 6). At 1-year follow-up examination, the patient had complete resolution of popliteal pain and swelling, without a recurrence of the popliteal cyst. The patient had full range of motion. The patient was strictly informed that she needed periodic follow-up to assess the wearing down of the tibial insert and to avoid delaying polyethylene replacement. DISCUSSION This case suggests that a dissecting popliteal cyst may occur after UKA as a sign of a malfunction and that treatment should be toward the joint, not the cyst itself. There are 3 different operative approaches to a popliteal cyst after an arthroplasty: simple cyst excision, revision of the implant with cyst excision, and simple revision of the implant. Pavlov et al.4 reported 2 cases of popliteal cyst after TKA that responded to conservative management. However, popliteal cysts are known to be caused by pre-existing pathology within the knee joint.
1026
K. YAMAKADO
FIGURE 2. (A) Preoperative anteroposterior radiograph. (B, C) Lateral radiographs following the intracyst injection of contrast medium. (C) Arrows show the abrading area of the tibial polyethylene insert and the metal tray. Note that there is no demonstrable communication between the cyst and joint cavity.
POPLITEAL CYST AFTER FAILED KNEE ARTHROPLASTY
FIGURE 3. Computed tomography after cystography shows a large popliteal cyst. Note that there is an extra-articular mass adjacent to the posterior joint capsule.
As Dirchl and Lachiewicz5 pointed out, excision of a popliteal cyst without correction of the intra-articular pathology seems likely to result in cyst recurrence. Therefore, treatment should be directed toward the primary intra-articular lesion and not toward the cyst itself, and simple cyst excision should be avoided.
FIGURE 4. Arthroscopic photograph shows that the centromedial part of the tibial polyethylene insert is worn down and the tibial tray is exposed.
1027
FIGURE 5. The opening of the connection between the popliteal cyst and joint space at the posteromedial compartment is seen. A 4.8-mm shaver is shown as calibration.
Dirchl and Lachiewicz5 also reported 4 cases of dissecting popliteal cyst as the presenting symptom of a malfunctioning TKA. In three of their patients, the cysts resolved without excision after revision of the failed TKA. Alternatively, Chan et al.6 recommended a 2-stage operation, consisting of open-cyst resection followed by revision TKA. In the present case, because the patient refused conversion to TKA and fortunately the tibial and femoral implants did not show loosening, the author used a minimally invasive operation: arthroscopic capsulotomy and evacuation of the cyst followed by tibial insert exchange. Sansone and De Ponti7 reported arthroscopic treatment for a popliteal cyst in a nonprosthetic knee. The treatment they describe consisted of the detection and destruction of a 1-way valvular connection between the knee joint and the cyst. In the present case, such a valve mechanism could not be detected; thus, the communication hole was created at the posteromedial capsule (Fig 5). Although the patient was satisfied with the outcome, this type of simple insert exchange is not recommended for the majority of failed UKA cases. Several authors8-10 warned that an isolated revision of the tibial polyethylene insert should not be performed, especially when there is accelerated wear of the insert within 10 years after the primary procedure in TKA.8 Close follow-up is mandatory to avoid missing repeated failure of the polyethylene.
1028
K. YAMAKADO REFERENCES 1. Adams R. Chronic rheumatoid arthritis of the knee. Dublin J Med Sci 1840;17:520. 2. Baker WM. On the formation of synovial cyst in the leg connection with disease of the knee joint. St Barthol Hosp Rep 1887;13:245. 3. Austin KS, Testa NN, Luntz RK, et al. Aspergillus infection of total knee arthroplasty presenting as a popliteal cyst: Case report and review of the literature. J Arthroplasty 1992;7:311314. 4. Pavlov H, Steinbach L, Fried SH. A posterior ascending popliteal cyst mimicking thrombophlebitis following total knee arthroplasty (TKA). Clin Orthop 1983;179:204-208. 5. Dirschl DR, Lachiewicz PF. Dissecting popliteal cyst as the presenting symptom of a malfunctioning total knee arthroplasty: Report of 4 cases. J Arthroplasty 1992;7:37-41. 6. Chan YS, Wang CJ, Shin CH. Two-stage operation for treatment of a large dissecting popliteal cyst after failed total knee arthroplasty. J Arthroplasty 2000;15:1068-1072. 7. Sansone V, De Ponti A. Arthroscopic treatment of popliteal cyst and associated intra-articular knee disorders in adults. Arthroscopy 1999;15:368-372. 8. Engh GA, Koralewicz LM, Pereles TR. Clinical results of modular polyethylene insert exchange with retention of total knee arthroplasty components. J Bone Joint Surg Am 2000;82: 516-523. 9. Babis GC, Trousdale RT, Pagnano MW, Morrey BF. Poor outcomes of isolated tibial insert exchange and arthrolysis for the management of stiffness following total knee arthroplasty. J Bone Joint Surg Am 2001;83:1534-1536. 10. Babis GC, Trousdale RT, Morrey BF, Bert JM. The effectiveness of isolated tibial insert exchange in revision total knee arthroplasty. J Bone Joint Surg Am 2002;84:64-68.
FIGURE 6. Posterior view of the left knee 3 months after the operation. Note that the popliteal cyst has disappeared.
Dissecting a Popliteal Cyst After Failed Unicompartmental Knee Arthroplasty Kotaro Yamakado, M.D.
Abstract: This report documents the first case of a popliteal cyst in a knee with failed unicompartmental knee arthroplasty (UKA). The cyst was treated successfully with the creation of a small communication hole between the posteromedial compartment and the popliteal cyst under direct arthroscopic visualization. This was followed by the replacement of a worn polyethylene insert via a small arthrotomy. Three months later, the popliteal mass had disappeared. This case suggests that a dissecting popliteal cyst may occur after UKA as one of the signs of a malfunction. It also suggests that treatment should be directed toward the joint and not the cyst itself. Key Words: Dissecting popliteal cyst—Unicompartmental knee arthroplasty—Polyethylene—Wear.
D
issecting popliteal cysts, which were first described by Adams1 in 1840 and further studied by Baker2 in 1877, occur most frequently as a result of intra-articular knee pathology. A popliteal cyst following unicompartmental knee arthroplasty (UKA) has never been reported, although there are a few reports concerning dissecting popliteal cysts associated with total knee arthroplasty (TKA).3-6 The author reports the first case of a popliteal cyst that occurred in a knee with failed UKA and symptoms of calf pain and functional disability. CASE REPORT A 78-year-old woman had undergone UKA of the left knee with a Miller/Galante Unicompartmental Knee System (Zimmer, Warsaw, IN) for osteoarthro-
From the Department of Orthopaedics, Kahoku Central Hospital, Kahoku-gun, Ishikawa Prefecture, Japan. Address correspondence and reprint requests to Kotaro Yamakado, M.D., Kahoku Central Hospital, Ro 51-2, Tsubata, Tsubata-machi, Kahoku-gun, Ishikawa Prefecture, Japan 929-0300. E-mail: [email protected] © 2002 by the Arthroscopy Association of North America 0749-8063/02/1809-3458$35.00/0 doi:10.1053/jars.2002.36485
sis 8 years earlier. The postoperative alignment of the leg was satisfactory, and the femoral component was implanted properly. However, the tibial tray was implanted in the valgus position. The postoperative course was uneventful until 5 years after surgery. At this time, the patient began to develop pain and recurring popliteal swelling of the left knee (Fig 1). On physical examination, a tense palpable mass (7 ⫻ 7 cm) was found in the posteromedial aspect of the knee. The patient’s knee had full range of motion and no effusion of the joint was found, but there was a slight tenderness and local heat at the medial joint line. Neurovascular status was normal. Aspiration of the cyst showed 60 mL of red turbid fluid, and the cyst recurred within 24 hours. Microbiological culture of the sample was negative. Stress radiographs showed correctable varus deformity, suggesting wear of the polyethylene insert and the tibial metal tray. Radiographs of the cyst after injecting radiopaque material were consistent with a popliteal cyst but did not show intra-articular communication (Fig 2). Computed tomography (CT) after cystography revealed an extra-articular mass adjacent to the posterior joint capsule (Fig 3). Serum laboratory analyses (complete blood count, prothrombin time, activated partial thromboplastin time, erythrocyte sedi-
1024 Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 9 (November-December), 2002: pp 1024-1028
POPLITEAL CYST AFTER FAILED KNEE ARTHROPLASTY
FIGURE 1. cyst.
The left knee on initial presentation. Note the popliteal
mentation rate, and C-reactive protein) were within normal limits. The patient refused formal revision by means of conversion to TKA because she believed the prosthesis was functioning well. Therefore, we performed arthroscopic capsulotomy of the posteromedial compartment (creation of a small communication hole between the posteromedial compartment and the popliteal cyst) followed by revision arthroplasty with polyethylene replacement under regional anesthesia. Three portals—anterolateral, anteromedial, and posteromedial—were used. On initial examination, there was proliferation of the synovium, which was stained black with metal debris. Using a shaver, we debrided the debris from the infrapatellar area, tibiofemoral joint, and remaining areas of the intercondylar notch. After resection of the medial meniscus remnant, it was clearly shown that the centromedial part of the tibial polyethylene
1025
insert was worn down and that the tibial tray was exposed (Fig 4). After the anterior compartments were examined, a posteromedial surgical portal was created under direct visualization with a 70° arthroscope passed through the lateral surgical portal and into the posteromedial compartment via the intercondylar notch. The shaver was introduced through the posteromedial portal with visual access through the anterolateral portal. After synovectomy of the posterior compartment, the posterior capsule was passed cautiously with the shaver, as planned using preoperative CT. When the communication hole between the joint space and the cyst was created, the cutting edge of the shaver was turned to prevent contact with the vascular structure of the popliteal region. The capsular communication hole was enlarged with the punch and the retrocutting punch and the cyst was evacuated. At the end of the capsulotomy, there was a capsular opening of 20 to 25 mm in diameter (Fig 5). After completion of the arthroscopy, an anterior midline incision measuring approximately 4 cm was made through the previous scar. A severely worn polyethylene tibial insert was retrieved. The tibial metal tray and femoral component were stable without signs of loosening. A new polyethylene insert was introduced, and the incision was closed. The areas of polyethylene wear noted at revision reflected the valgus position of the tibial tray (centromedial point loading). Gait and daily activity was allowed on the first postoperative day. Three months later, the popliteal mass had disappeared (Fig 6). At 1-year follow-up examination, the patient had complete resolution of popliteal pain and swelling, without a recurrence of the popliteal cyst. The patient had full range of motion. The patient was strictly informed that she needed periodic follow-up to assess the wearing down of the tibial insert and to avoid delaying polyethylene replacement. DISCUSSION This case suggests that a dissecting popliteal cyst may occur after UKA as a sign of a malfunction and that treatment should be toward the joint, not the cyst itself. There are 3 different operative approaches to a popliteal cyst after an arthroplasty: simple cyst excision, revision of the implant with cyst excision, and simple revision of the implant. Pavlov et al.4 reported 2 cases of popliteal cyst after TKA that responded to conservative management. However, popliteal cysts are known to be caused by pre-existing pathology within the knee joint.
1026
K. YAMAKADO
FIGURE 2. (A) Preoperative anteroposterior radiograph. (B, C) Lateral radiographs following the intracyst injection of contrast medium. (C) Arrows show the abrading area of the tibial polyethylene insert and the metal tray. Note that there is no demonstrable communication between the cyst and joint cavity.
POPLITEAL CYST AFTER FAILED KNEE ARTHROPLASTY
FIGURE 3. Computed tomography after cystography shows a large popliteal cyst. Note that there is an extra-articular mass adjacent to the posterior joint capsule.
As Dirchl and Lachiewicz5 pointed out, excision of a popliteal cyst without correction of the intra-articular pathology seems likely to result in cyst recurrence. Therefore, treatment should be directed toward the primary intra-articular lesion and not toward the cyst itself, and simple cyst excision should be avoided.
FIGURE 4. Arthroscopic photograph shows that the centromedial part of the tibial polyethylene insert is worn down and the tibial tray is exposed.
1027
FIGURE 5. The opening of the connection between the popliteal cyst and joint space at the posteromedial compartment is seen. A 4.8-mm shaver is shown as calibration.
Dirchl and Lachiewicz5 also reported 4 cases of dissecting popliteal cyst as the presenting symptom of a malfunctioning TKA. In three of their patients, the cysts resolved without excision after revision of the failed TKA. Alternatively, Chan et al.6 recommended a 2-stage operation, consisting of open-cyst resection followed by revision TKA. In the present case, because the patient refused conversion to TKA and fortunately the tibial and femoral implants did not show loosening, the author used a minimally invasive operation: arthroscopic capsulotomy and evacuation of the cyst followed by tibial insert exchange. Sansone and De Ponti7 reported arthroscopic treatment for a popliteal cyst in a nonprosthetic knee. The treatment they describe consisted of the detection and destruction of a 1-way valvular connection between the knee joint and the cyst. In the present case, such a valve mechanism could not be detected; thus, the communication hole was created at the posteromedial capsule (Fig 5). Although the patient was satisfied with the outcome, this type of simple insert exchange is not recommended for the majority of failed UKA cases. Several authors8-10 warned that an isolated revision of the tibial polyethylene insert should not be performed, especially when there is accelerated wear of the insert within 10 years after the primary procedure in TKA.8 Close follow-up is mandatory to avoid missing repeated failure of the polyethylene.
1028
K. YAMAKADO REFERENCES 1. Adams R. Chronic rheumatoid arthritis of the knee. Dublin J Med Sci 1840;17:520. 2. Baker WM. On the formation of synovial cyst in the leg connection with disease of the knee joint. St Barthol Hosp Rep 1887;13:245. 3. Austin KS, Testa NN, Luntz RK, et al. Aspergillus infection of total knee arthroplasty presenting as a popliteal cyst: Case report and review of the literature. J Arthroplasty 1992;7:311314. 4. Pavlov H, Steinbach L, Fried SH. A posterior ascending popliteal cyst mimicking thrombophlebitis following total knee arthroplasty (TKA). Clin Orthop 1983;179:204-208. 5. Dirschl DR, Lachiewicz PF. Dissecting popliteal cyst as the presenting symptom of a malfunctioning total knee arthroplasty: Report of 4 cases. J Arthroplasty 1992;7:37-41. 6. Chan YS, Wang CJ, Shin CH. Two-stage operation for treatment of a large dissecting popliteal cyst after failed total knee arthroplasty. J Arthroplasty 2000;15:1068-1072. 7. Sansone V, De Ponti A. Arthroscopic treatment of popliteal cyst and associated intra-articular knee disorders in adults. Arthroscopy 1999;15:368-372. 8. Engh GA, Koralewicz LM, Pereles TR. Clinical results of modular polyethylene insert exchange with retention of total knee arthroplasty components. J Bone Joint Surg Am 2000;82: 516-523. 9. Babis GC, Trousdale RT, Pagnano MW, Morrey BF. Poor outcomes of isolated tibial insert exchange and arthrolysis for the management of stiffness following total knee arthroplasty. J Bone Joint Surg Am 2001;83:1534-1536. 10. Babis GC, Trousdale RT, Morrey BF, Bert JM. The effectiveness of isolated tibial insert exchange in revision total knee arthroplasty. J Bone Joint Surg Am 2002;84:64-68.
FIGURE 6. Posterior view of the left knee 3 months after the operation. Note that the popliteal cyst has disappeared.