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Radial Displacement of Lateral Meniscus After Partial Meniscectomy
Case Report
Radial Displacement of Lateral Meniscus After Partial Meniscectomy Nam-Hong Choi, M.D.
Abstract: Radial displacement or extrusion of the meniscus has been reported as a complication after meniscal transplantation and is sometimes observed in knees with advanced osteoarthritis. In this report, the case of a patient with radial displacement of the lateral meniscus after partial meniscectomy is presented. He had an incomplete discoid lateral meniscus with an anterior horn tear. The inner portion of the lateral meniscus was excised to leave a width of 8 to 10 mm. However, follow-up magnetic resonance imaging showed radial displacement of the mid-body of the lateral meniscus and a compatible finding of chondromalacia of the lateral compartment of the knee. Key Words: Meniscus—Meniscectomy—Radial displacement.
R
adial displacement or extrusion of the meniscus has been reported as a complication after meniscal transplantation. Potter et al.1 reported that frank extrusion of the transplant was seen in association with full-thickness chondral defects, condylar flattening, and posterior horn meniscal degeneration. Stollsteimer et al.2 reported 1 case of peripheral meniscal extrusion after 22 meniscal transplantations. Some degree of radial displacement of the meniscus is sometimes observed, particularly in knees with advanced arthritic changes. Kenny3 stated that Fairbank’s signs of osteoarthritis could develop in knees that exhibit significant radial displacement of the medial meniscus. To my knowledge, there is no report of radial displacement of the meniscus after partial me-
From The Department of Orthopaedic Surgery, Eulji Medical Center, Seoul, Korea. Correspondence and reprint requests to Nam-Hong Choi, M.D., Department of Orthopaedic Surgery, Eulji Medical Center, 280-1, Hagye-1-dong, Nowon-gu, Seoul, 139-711, Korea. E-mail: [email protected] © 2006 by the Arthroscopy Association of North America Cite this article as: Choi N-H. Radial displacement of lateral meniscus after partial meniscectomy. Arthroscopy 2006;22: 575.e1-575.e4 [doi:10.1016/j.arthro.2005.11.007]. 0749-8063/06/2205-4625$32.00/0 doi:10.1016/j.arthro.2005.11.007
niscectomy not associated with meniscal transplantation or advanced arthritic changes.
CASE REPORT A 20-year-old college soccer player visited the hospital because of right knee pain of 4 months’ duration. He had experienced multiple minor injuries during soccer games. He complained of squatting pain, and a sense of catching and giving way. Physical examination showed that his right knee was stable and the range of motion was normal. There was no effusion or joint-line tenderness. McMurray’s test elicited pain in the medial aspect of the knee in internal rotation. Radiographs of the right knee were normal. Magnetic resonance imaging (MRI) revealed an incomplete discoid lateral meniscus (Fig 1). The cruciate ligaments and the medial meniscus were intact. On arthroscopic examination, incomplete discoid lateral meniscus with a longitudinal tear of the anterior horn was found. The inner portion of the discoid lateral meniscus was excised to leave the width of the lateral meniscus 8 to 10 mm (Fig 2). The tear of the anterior horn was repaired with an all-inside technique. After surgery, the patient underwent a routine post-
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 22, No 5 (May), 2006: pp 575.e1-575.e4
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N-H. CHOI Radial displacement was measured as the greatest distance from the most peripheral aspect of the meniscus to the border of the tibial plateau excluding any osteophyte on coronal images. The patient had radial displacement of 4.1 mm. The mid-body of the lateral meniscus was not in contact with the weight-bearing surfaces of the lateral femoral condyle and tibial plateau. The subchondral bone of the lateral femoral condyle and tibial plateau showed decreased signal intensity, compatible with chondromalacia of the lateral compartment of right knee (Fig 3). The tear of the anterior horn of the lateral meniscus was partially healed. Meniscal allograft transplantation was planned. DISCUSSION
FIGURE 1. Preoperative MRI showing an incomplete discoid lateral meniscus without any tear.
operative protocol. Full weight bearing was allowed in a knee immobilizer for 6 weeks. However, extension beyond 30° from full flexion was not allowed for 6 weeks to protect the repaired anterior horn. After 6 weeks, the patient was allowed to start full weight bearing without a brace. Jumping activity was permitted 3 months after surgery. The patient returned to the hospital 14 months after surgery because he had pain in extension and an effusion. His right knee showed range of motion from 10° to 120° of flexion. McMurray’s test elicited pain at the lateral aspect of the knee during internal and external rotation. Standing posteroanterior view radiographs of both knees showed no narrowing of the joint space of the lateral compartment of the right knee compared with the left. However, his standing fulllength radiograph showed valgus deformity of 8° of the right lower extremity. Follow-up MRI showed radial displacement of the mid-body of the lateral meniscus; it was a grade 3 radial displacement, determined with criteria by Adams et al.4
Menisci are vital structures for load bearing and distribution in the knee joint. The load bearing across the medial compartment is shared equally between the articular cartilage and medial meniscus, whereas the lateral meniscus bears 70% of the load transmitted across the lateral compartment.5 If the meniscus is radially displaced into the medial or lateral gutter, the effective load-bearing mechanism will be diminished and degeneration of articular cartilage may occur. The effect of radial displacement of the meniscus can be understood from the results of total meniscectomy. The contact area between the femur and tibia decreases by approximately 40% after total meniscectomy.6,7 Therefore, markedly increased contact stress by radial displacement of the meniscus may contribute to degeneration of articular cartilage. Few articles have discussed the effect of extrusion or radial displacement of the meniscus. Kenny3 stud-
FIGURE 2. The inner portion of the discoid lateral meniscus was excised to leave the nearly normal width of the lateral meniscus.
RADIAL DISPLACEMENT OF LATERAL MENISCUS
FIGURE 3. Postoperative MRI showing radial displacement of the lateral meniscus and decreased signal intensity of the subchondral bone of the lateral femoral condyle and tibial plateau.
ied the correlation between radial displacement of the medial meniscus and Fairbank’s signs. He suggested that radial displacement might be related to loss of meniscal function because the radiographic signs are similar to postmeniscectomy status. Gale et al.8 reported that there was a strong correlation between the degree of medial meniscal subluxation and the severity of medial joint space narrowing. They also stated that similar results were present in the lateral compartment. Radial displacement of the meniscus may contribute to the development of joint-space narrowing and arthritic changes. Gale et al.8 postulated that some of the joint-space narrowing of the knee might be attributable to meniscal extrusion and not necessarily loss of hyaline cartilage. Sugita et al.9 studied the macroscopic and histologic findings of medial menisci and medial tibial plateau specimens obtained during total knee arthroplasty. They suggested that radial displacement of the medial meniscus precedes narrowing of
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the medial joint space during progression of varus osteoarthritis. Adams et al.4 reported that initial narrowing of the joint space observed in their patients was the result of meniscal extrusion and not thinning of cartilage in 17 patients. They believed that radial displacement of the meniscus contributes significantly to joint-space narrowing in the early stage of osteoarthritis. There is no report concerning the correlation of degree of radial displacement of the meniscus and its effects. Vedi et al.10 measured meniscal movement in normal knees under load using an open MRI scanner. They reported that the lateral meniscus displaced 3.7 mm radially on weight-bearing and 3.4 mm in non– weight-bearing. The criterion for radial displacement was defined as a distance of 3 mm or more between the peripheral border of the meniscus and the edge of the tibial plateau.11 In this study, the patient had radial displacement of 4.1 mm in non–weight-bearing. Therefore, radial displacement of the meniscus in this patient must be a pathologic finding. Also, the patient has had signal intensity compatible with chondromalacia in the lateral compartment of the knee. I postulate that chondromalacia in this patient might have occurred because of radial displacement of the lateral meniscus. In this case, as shown in the arthroscopic photograph, sufficient margin of the discoid lateral meniscus was preserved after partial meniscectomy (Fig 2). However, the lateral meniscus was radially displaced after surgery. Partial meniscectomy may have a role in the development of radial displacement. Fukubayashi and Kurosawa6 stated that a single cut or tear to the radial edge of the meniscus eliminates hoop stress and contributes to mediolateral subluxation of the meniscus. However, the exact cause of the radial displacement was unknown. In conclusion, radial displacement of the meniscus has significant clinical importance and can develop without meniscal transplantation or advanced arthritic changes. Further longitudinal studies will be necessary to elucidate the correlation between radial displacement of the meniscus and initiation of osteoarthritis of the knee. REFERENCES 1. Potter HG, Rodeo SA, Wickiewicz TL, Warren RF. MR imaging of meniscal allografts: Correlation with clinical and arthroscopic outcomes. Radiology 1996;198:509-514. 2. Stollsteimer GT, Shelton WR, Dukes A, Bomboy AL. Meniscal allografts transplantation: A 1-to 5-year follow-up of 22 patients. Arthroscopy 2000;29:410-414.
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3. Kenny C. Radial displacement of the medial meniscus and Fairbank’s signs. Clin Orthop 1997;339:163-173. 4. Adams JG, McAlindon T, Dimmasi M, Carey J, Eustace S. Contribution of meniscal extrusion and cartilage loss to joint space narrowing in osteoarthritis. Clin Radiol 1999;54:502-506. 5. Walker PS, Erkman MJ. The role of the menisci in force transmission across the knee. Clin Orthop 1975;109:184-192. 6. Fukubayashi T, Kurosawa H. The contact area and pressure distribution pattern of the knee. Acta Orthop Scand 1980;149: 871-879. 7. Kurosawa H, Fukubayashi T, Nakajima H. Loadbearing mode of the knee joint: Physical behavior of the knee joint with or without menisci. Clin Orthop 1980;149:283-290.
8. Gale DR, Chaisson CE, Tottterman MS, Schwarts RK, Gale ME, Felson D. Meniscal subluxation association with osteoarthritis and joint space narrowing. Osteoarthritis Cartilage 1999;7:526-532. 9. Sugita T, Kawamata T, Yoshizumi Y, Sato K. Radial displacement of the medial meniscus in varus osteoarthritis of the knee. Clin Orthop 2001;387:171-177. 10. Vedi V, Williams A, Tennant SJ, Spouse E, Hunt DM, Gedroyc WM. Meniscal movement. An in-vivo study dynamic MRI. J Bone Joint Surg Br 1999;81:37-41. 11. Breitenseher MJ, Trattnig S, Dobrocky I, et al. MR imaging of meniscal subluxation in the knee. Acta Radiol 1997;38:876879.
Radial Displacement of Lateral Meniscus After Partial Meniscectomy Nam-Hong Choi, M.D.
Abstract: Radial displacement or extrusion of the meniscus has been reported as a complication after meniscal transplantation and is sometimes observed in knees with advanced osteoarthritis. In this report, the case of a patient with radial displacement of the lateral meniscus after partial meniscectomy is presented. He had an incomplete discoid lateral meniscus with an anterior horn tear. The inner portion of the lateral meniscus was excised to leave a width of 8 to 10 mm. However, follow-up magnetic resonance imaging showed radial displacement of the mid-body of the lateral meniscus and a compatible finding of chondromalacia of the lateral compartment of the knee. Key Words: Meniscus—Meniscectomy—Radial displacement.
R
adial displacement or extrusion of the meniscus has been reported as a complication after meniscal transplantation. Potter et al.1 reported that frank extrusion of the transplant was seen in association with full-thickness chondral defects, condylar flattening, and posterior horn meniscal degeneration. Stollsteimer et al.2 reported 1 case of peripheral meniscal extrusion after 22 meniscal transplantations. Some degree of radial displacement of the meniscus is sometimes observed, particularly in knees with advanced arthritic changes. Kenny3 stated that Fairbank’s signs of osteoarthritis could develop in knees that exhibit significant radial displacement of the medial meniscus. To my knowledge, there is no report of radial displacement of the meniscus after partial me-
From The Department of Orthopaedic Surgery, Eulji Medical Center, Seoul, Korea. Correspondence and reprint requests to Nam-Hong Choi, M.D., Department of Orthopaedic Surgery, Eulji Medical Center, 280-1, Hagye-1-dong, Nowon-gu, Seoul, 139-711, Korea. E-mail: [email protected] © 2006 by the Arthroscopy Association of North America Cite this article as: Choi N-H. Radial displacement of lateral meniscus after partial meniscectomy. Arthroscopy 2006;22: 575.e1-575.e4 [doi:10.1016/j.arthro.2005.11.007]. 0749-8063/06/2205-4625$32.00/0 doi:10.1016/j.arthro.2005.11.007
niscectomy not associated with meniscal transplantation or advanced arthritic changes.
CASE REPORT A 20-year-old college soccer player visited the hospital because of right knee pain of 4 months’ duration. He had experienced multiple minor injuries during soccer games. He complained of squatting pain, and a sense of catching and giving way. Physical examination showed that his right knee was stable and the range of motion was normal. There was no effusion or joint-line tenderness. McMurray’s test elicited pain in the medial aspect of the knee in internal rotation. Radiographs of the right knee were normal. Magnetic resonance imaging (MRI) revealed an incomplete discoid lateral meniscus (Fig 1). The cruciate ligaments and the medial meniscus were intact. On arthroscopic examination, incomplete discoid lateral meniscus with a longitudinal tear of the anterior horn was found. The inner portion of the discoid lateral meniscus was excised to leave the width of the lateral meniscus 8 to 10 mm (Fig 2). The tear of the anterior horn was repaired with an all-inside technique. After surgery, the patient underwent a routine post-
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 22, No 5 (May), 2006: pp 575.e1-575.e4
575.e1
575.e2
N-H. CHOI Radial displacement was measured as the greatest distance from the most peripheral aspect of the meniscus to the border of the tibial plateau excluding any osteophyte on coronal images. The patient had radial displacement of 4.1 mm. The mid-body of the lateral meniscus was not in contact with the weight-bearing surfaces of the lateral femoral condyle and tibial plateau. The subchondral bone of the lateral femoral condyle and tibial plateau showed decreased signal intensity, compatible with chondromalacia of the lateral compartment of right knee (Fig 3). The tear of the anterior horn of the lateral meniscus was partially healed. Meniscal allograft transplantation was planned. DISCUSSION
FIGURE 1. Preoperative MRI showing an incomplete discoid lateral meniscus without any tear.
operative protocol. Full weight bearing was allowed in a knee immobilizer for 6 weeks. However, extension beyond 30° from full flexion was not allowed for 6 weeks to protect the repaired anterior horn. After 6 weeks, the patient was allowed to start full weight bearing without a brace. Jumping activity was permitted 3 months after surgery. The patient returned to the hospital 14 months after surgery because he had pain in extension and an effusion. His right knee showed range of motion from 10° to 120° of flexion. McMurray’s test elicited pain at the lateral aspect of the knee during internal and external rotation. Standing posteroanterior view radiographs of both knees showed no narrowing of the joint space of the lateral compartment of the right knee compared with the left. However, his standing fulllength radiograph showed valgus deformity of 8° of the right lower extremity. Follow-up MRI showed radial displacement of the mid-body of the lateral meniscus; it was a grade 3 radial displacement, determined with criteria by Adams et al.4
Menisci are vital structures for load bearing and distribution in the knee joint. The load bearing across the medial compartment is shared equally between the articular cartilage and medial meniscus, whereas the lateral meniscus bears 70% of the load transmitted across the lateral compartment.5 If the meniscus is radially displaced into the medial or lateral gutter, the effective load-bearing mechanism will be diminished and degeneration of articular cartilage may occur. The effect of radial displacement of the meniscus can be understood from the results of total meniscectomy. The contact area between the femur and tibia decreases by approximately 40% after total meniscectomy.6,7 Therefore, markedly increased contact stress by radial displacement of the meniscus may contribute to degeneration of articular cartilage. Few articles have discussed the effect of extrusion or radial displacement of the meniscus. Kenny3 stud-
FIGURE 2. The inner portion of the discoid lateral meniscus was excised to leave the nearly normal width of the lateral meniscus.
RADIAL DISPLACEMENT OF LATERAL MENISCUS
FIGURE 3. Postoperative MRI showing radial displacement of the lateral meniscus and decreased signal intensity of the subchondral bone of the lateral femoral condyle and tibial plateau.
ied the correlation between radial displacement of the medial meniscus and Fairbank’s signs. He suggested that radial displacement might be related to loss of meniscal function because the radiographic signs are similar to postmeniscectomy status. Gale et al.8 reported that there was a strong correlation between the degree of medial meniscal subluxation and the severity of medial joint space narrowing. They also stated that similar results were present in the lateral compartment. Radial displacement of the meniscus may contribute to the development of joint-space narrowing and arthritic changes. Gale et al.8 postulated that some of the joint-space narrowing of the knee might be attributable to meniscal extrusion and not necessarily loss of hyaline cartilage. Sugita et al.9 studied the macroscopic and histologic findings of medial menisci and medial tibial plateau specimens obtained during total knee arthroplasty. They suggested that radial displacement of the medial meniscus precedes narrowing of
575.e3
the medial joint space during progression of varus osteoarthritis. Adams et al.4 reported that initial narrowing of the joint space observed in their patients was the result of meniscal extrusion and not thinning of cartilage in 17 patients. They believed that radial displacement of the meniscus contributes significantly to joint-space narrowing in the early stage of osteoarthritis. There is no report concerning the correlation of degree of radial displacement of the meniscus and its effects. Vedi et al.10 measured meniscal movement in normal knees under load using an open MRI scanner. They reported that the lateral meniscus displaced 3.7 mm radially on weight-bearing and 3.4 mm in non– weight-bearing. The criterion for radial displacement was defined as a distance of 3 mm or more between the peripheral border of the meniscus and the edge of the tibial plateau.11 In this study, the patient had radial displacement of 4.1 mm in non–weight-bearing. Therefore, radial displacement of the meniscus in this patient must be a pathologic finding. Also, the patient has had signal intensity compatible with chondromalacia in the lateral compartment of the knee. I postulate that chondromalacia in this patient might have occurred because of radial displacement of the lateral meniscus. In this case, as shown in the arthroscopic photograph, sufficient margin of the discoid lateral meniscus was preserved after partial meniscectomy (Fig 2). However, the lateral meniscus was radially displaced after surgery. Partial meniscectomy may have a role in the development of radial displacement. Fukubayashi and Kurosawa6 stated that a single cut or tear to the radial edge of the meniscus eliminates hoop stress and contributes to mediolateral subluxation of the meniscus. However, the exact cause of the radial displacement was unknown. In conclusion, radial displacement of the meniscus has significant clinical importance and can develop without meniscal transplantation or advanced arthritic changes. Further longitudinal studies will be necessary to elucidate the correlation between radial displacement of the meniscus and initiation of osteoarthritis of the knee. REFERENCES 1. Potter HG, Rodeo SA, Wickiewicz TL, Warren RF. MR imaging of meniscal allografts: Correlation with clinical and arthroscopic outcomes. Radiology 1996;198:509-514. 2. Stollsteimer GT, Shelton WR, Dukes A, Bomboy AL. Meniscal allografts transplantation: A 1-to 5-year follow-up of 22 patients. Arthroscopy 2000;29:410-414.
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3. Kenny C. Radial displacement of the medial meniscus and Fairbank’s signs. Clin Orthop 1997;339:163-173. 4. Adams JG, McAlindon T, Dimmasi M, Carey J, Eustace S. Contribution of meniscal extrusion and cartilage loss to joint space narrowing in osteoarthritis. Clin Radiol 1999;54:502-506. 5. Walker PS, Erkman MJ. The role of the menisci in force transmission across the knee. Clin Orthop 1975;109:184-192. 6. Fukubayashi T, Kurosawa H. The contact area and pressure distribution pattern of the knee. Acta Orthop Scand 1980;149: 871-879. 7. Kurosawa H, Fukubayashi T, Nakajima H. Loadbearing mode of the knee joint: Physical behavior of the knee joint with or without menisci. Clin Orthop 1980;149:283-290.
8. Gale DR, Chaisson CE, Tottterman MS, Schwarts RK, Gale ME, Felson D. Meniscal subluxation association with osteoarthritis and joint space narrowing. Osteoarthritis Cartilage 1999;7:526-532. 9. Sugita T, Kawamata T, Yoshizumi Y, Sato K. Radial displacement of the medial meniscus in varus osteoarthritis of the knee. Clin Orthop 2001;387:171-177. 10. Vedi V, Williams A, Tennant SJ, Spouse E, Hunt DM, Gedroyc WM. Meniscal movement. An in-vivo study dynamic MRI. J Bone Joint Surg Br 1999;81:37-41. 11. Breitenseher MJ, Trattnig S, Dobrocky I, et al. MR imaging of meniscal subluxation in the knee. Acta Radiol 1997;38:876879.