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Dislocation of the posterior stabilized total knee arthroplasty
Dislocation of the Posterior Stabilized Total Knee Arthroplasty A Report of Two Cases
Brian J. Galinat, MD, Joseph V. Vemace, MD, Robert E. Booth, Jr., MD, and Richard H. Rothman, MD, PhD
Abstract: This brief report details the previously unreported complication of dislocation of the posterior stabililzed total knee arthroplasty. Both patients had valgus deformities requiring extensive release of the contracted lateral soft tissues. The mechanism of dislocation was one of slight flexion and external rotation. The prosthetic tibial spine became locked posterior to the femoral cam. Reduction was accomplished by applying traction and anterior translation on the tibia with the knee slightly flexed. No redislocations have occurred. A literature review is presented and the authors discuss technique modifications that may prevent this complication.
Early results of the total condylar knee arthroplasty demonstrated some mild limitations thought to be related to the design of the prosthesis. These included difficulty with stair climbing, limited flexion, and subluxation of the prosthesis (4, 6). The design was modified to include a tibial spine and femoral cam in an attempt to reproduce, in part, the function of the posterior cruciate ligament. Both flexion and ability to climb stairs improved with this posterior stabilized condylar prosthesis. Complications, however, have also occurred and may be in part attributable to this design. In his initial review of 118 knees with a 2 - 4 - y e a r follow-up period, Insall (10) reported 10 patellar fractures, 2 cases ofpatellar subluxation, and 3 patients w h o had what has subsequently been described as the patellar " d u n k " syndrome (6). Two of the prostheses had loosened and
From the Department of Orthopaedic Surgery, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania.
Reprint requests: Brian J. Galinat,MD, Department of Orthopaedic Surgery, 1015 Walnut Street, Philadelphia,PA 19107.
required revision and 31% had evidence of radiolucency about the tibial component. Other studies of this total knee arthroplasty design have demonstrated similar results and complications (5, 13). Since 1984, 832 posterior stabilized condylar prostheses have been inserted at Pennsylvania Hospital. We detail the previously unreported complication of dislocation of this particular prosthesis.
Case Reports Case 1 A 64-year-old w o m a n had a right posterior stabilized total knee arthroplasty for progressive knee pain that became unresponsive to nonoperative management. A preoperative standing roentgenogram demonstrated a 16 ° valgus angulation (Fig. 1A). Her flexion arc was from 0 ° to 100 °, and no
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The Journal of Arthroplasty Vol. 3 No. 4 December 1988
Fig. 1. Case 1, {A) Preoperative standing roentgenogram, showing 16° of vatgus angulation of the right knee. (B) Postoperative roentgenogram. (C} Lateral roentgenogram, documenting J3e posterior dislocation. (D} Lateral roentgenogram after reduction.
Posterior Stabilized Total Knee Dislocations
ligamentous laxity was noted. At surgery, the contracted lateral side required the release of the iliotibial band insertion, the popliteus, the lateral collateral origin, and the lateral patellar retinaculum. After the bony cuts were made, a 7.5-mm thick tibial plateau was found to provide appropriate soft tissue tension in flexion and extension. The patient's initial postoperative course was unremarkable. Roentgenograms revealed the leg to be well aligned in 7 ° of valgus (Fig. 1B). She had achieved motion from 0 ° to 100 ° by 6 weeks after surgery. Three months after surgery, early symptoms of the patellar "clunk" syndrome occurred (6). This progressed and was managed with arthroscopy 4 months after her total knee arthroplasty. She again regained excellent function and pain-free motion to 100 °. Eight months after operation, she presented to the emergency room stating that when getting out of bed, she felt a "pop" and was unable to move her knee because of pain. Further questioning revealed tha! at the time of the dislocation, her knee was flexed approximately 45 ° and the tibia was externally rotated. There was no neurovascular compromise.
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Roentgenograms documented the posterior dislocation (Fig. 1C). Reduction was accomplished by one person using longitudinal traction and extension to 20 ° while an anterior translation force was applied to the proximal tibia (Fig. 1D). Sedation was not required. The patient was maintained in a knee immobilizer full time for 1 month and then at night for 1 month. No redislocations have occurred in the 18 months since the reduction, and the patient has maintained motion from 0 ° to 100 °.
Case 2
A 73-year-old woman had a left posterior stabilized total knee arthroplasty for treatment of degenerative arthritis. A preoperative standing roentgenogram demonstrated a 30 ° valgus angulation (Fig. 2A). Her flexion arc was from 10° to 90 °. The valgus angulation was passively correctable to approximately 10°. At surgery, the contracted lateral side required the
Fig. 2. Case 2. (A) Preoperative standing roentgenogram, showing a 30° valgus angulation of the right knee. (B) Lateral roentgenogram, documenting the posterior dislocation.
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release of the iliotibial band distally, the lateral collateral ligament and popliteus t e n d o n f r o m the femur, and the lateral patellar retinaculum. A 12.5m m tibial plateau thickness was f o u n d to provide good stability in flexion and extension. Postoperative roentgenograms revealed the leg to be in 8 ° of valgus. Shortly after discharge (1 m o n t h after operation) she sustained a posterior dislocation after externally rotating the tibia while the k n e e was flexed approximately 20 ° (Fig. 2B). There was n o neurovascular compromise. Reduction was easily accomplished with traction and application o f a n anterior translation force to the proximal tibia. T h e patient was maintained in a knee immobilizer for 1 month. No redislocations have occurred in the 18 m o n t h s since the reduction, and her flexion arc is from 5 ° to 110 °.
Discussion Dislocation of a total knee prosthesis is e x t r e m e l y u n c o m m o n . Published works by Insall m e n t i o n e d 4 cases of posterior subluxation of the tibia in 220 total condylar arthroplasties (7, 8). Before o p e r a t i o n , two of these had severe valgus deformities, o n e was n e u tral, and one was in 10 ° of varus. Two required revision, h o w e v e r n o specific details w e r e given w i t h regard to collateral ligament status or c o m p o n e n t positioning. A single case of total condylar k n e e dislocation presented by Bargren (1) was ascribed to malpositioning of the tibia] component. At revision, the tibial c o m p o n e n t was found to be directed at 30 ° medial to the tibia] tubercle. Of 94 knees requiring revision in a study b y Cameron (2), 3 had rotatory subluxation due to excessive internal rotation of the tibial c o m p o n e n t a n d two had anteroposterior instability. The sample p o p u l a tion was from a survey of 700 total k n e e arthroplasties, h o w e v e r no mention was m a d e of the type of arthroplasties used. A report of a dislocation of one s e m i c o n s t r a i n e d prosthesis that was inserted as a revision was recently presented by DenHartog (3). The design of this arthroplasty allows the retention of the p o s t e r i o r crnciate ligament. At the time of insertion, the cruciate ligaments were found to be nonfunctional. T h e author r e c o m m e n d e d using a posterior stabilized (cruciate replacement) prosthesis to p r e v e n t dislocation w h e n the posterior cruciate was absent. In our t w o cases, a posterior stabilized prosthesis was used. Both patients had valgus deformities re-
quiring e x t e n s i v e release of the contracted lateral soft tissues. T h e m e c h a n i s m of dislocation was one of slight flexion and external rotation. Reduction was easily a c c o m p l i s h e d with traction and anterior translation o n a slightly flexed knee. I n s p e c t i o n of a posterior stabilized total knee m o d e l reveals the femoral cam to be minimally restrained b y the tibial spine in the terminal 20 ° of extension. Excessive external rotation allows contact b e t w e e n the lateral aspect of the tibial spine and the medial aspect of the lateral femoral condyle. The fibial spine m a y t h e n lever o n this point to clear the cam, resulting in a posterior dislocation. W e r e c o m m e n d caution in performing the lateral soft tissue release required in the severe valgus knee. The release should provide balancing of the soft tissues w i t h the leg in an anatomic alignment. The soft tissue t e n s i o n should be clinically assessed in extension, 90 ° o f flexion, and 2 0 ° - 3 0 ° of flexion before a n y b o n y cuts are made. Medial and lateral soft tissue tension should be equivalent before the components are inserted. A lateral peripatellar approach is currently being evaluated in the severe valgus knee. This a p p r o a c h m a y allow improved exposure and more accurate m a n a g e m e n t of the contracted lateral soft tissues. It is h o p e d that these technique modifications will p r e v e n t further occurrences of this problem.
Acknowledgment The authors t h a n k A n n Louise Smith for her assistance in preparing the manuscript.
References 1. Bargren JH: Total knee dislocation due to rotatory malalignment of the tibial component: a case report. Clin Orthop 147:271, 1980 2. Cameron HU, Hunter GU: Failure in total knee arthroplasty. Clin Orthop 170:141, 1982 3. DenHartog BD, McQueen DA, Garcia GO: Traumatic posterior dislocation of a semiconstrained total knee arthroplasty: a case report. Contemp Orthop 15:41, 1987 4. Greenwald SA, Black JD, Matejczyk MB: Total knee replacement. AAOS Instruct Cour Lect 30:301, 1981 5. Figgie HE, Goldberg VM, Heiple KG et al: The influence of tibial-patellofemoral location on function of the knee in patients with the posterior stabilized condylar knee prosthesis. J Bone Joint Surg 68A:1035, 1986
Posterior Stabitized Total Knee DisIocations
6. Hozack WJ, Booth RE, Balderston RA, Rothmaa RH: The patellar "clunk" syndrome. Clin Orthop 231:79, 1988 7. Insall J, Scott WN, Ranawat C: The total condylar knee prosthesis: a report of two hundred and twenty cases. J Bone Joint Surg 61A:173, 1979 8. Insall JN, Hood RW, Flawn LB, Sullivan DJ: The total condylar knee prosthesis in gonarthrosis. J Bone Joint Surg 65A:619, 1983 9. Insa]l JN, Kelly M: The total condylar prosthesis. Clin Onhop 205:43, 1986
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10. Insall JN, Lachiewicz PF, Burstein AH: The posterior stabilized condylar prosthesis: a modification of the total condylar design. J Bone Joint Surg 64A:1317, 1982 11. Laskin RS: Total condylar knee replacement in rheumatoid arthritis. J Bone Joint Surg 63A:29, 1985 12. Scott RD, Volatile TB: Twelve years experience with posterior cruciate retaining total knee arthroplasty. Clin Orthop 205:100, 1986 13. Scott WN, Rubinstein M: Posterior stabilized knee arthroplasty. Clin Or~hop 205:138, 1986
Brian J. Galinat, MD, Joseph V. Vemace, MD, Robert E. Booth, Jr., MD, and Richard H. Rothman, MD, PhD
Abstract: This brief report details the previously unreported complication of dislocation of the posterior stabililzed total knee arthroplasty. Both patients had valgus deformities requiring extensive release of the contracted lateral soft tissues. The mechanism of dislocation was one of slight flexion and external rotation. The prosthetic tibial spine became locked posterior to the femoral cam. Reduction was accomplished by applying traction and anterior translation on the tibia with the knee slightly flexed. No redislocations have occurred. A literature review is presented and the authors discuss technique modifications that may prevent this complication.
Early results of the total condylar knee arthroplasty demonstrated some mild limitations thought to be related to the design of the prosthesis. These included difficulty with stair climbing, limited flexion, and subluxation of the prosthesis (4, 6). The design was modified to include a tibial spine and femoral cam in an attempt to reproduce, in part, the function of the posterior cruciate ligament. Both flexion and ability to climb stairs improved with this posterior stabilized condylar prosthesis. Complications, however, have also occurred and may be in part attributable to this design. In his initial review of 118 knees with a 2 - 4 - y e a r follow-up period, Insall (10) reported 10 patellar fractures, 2 cases ofpatellar subluxation, and 3 patients w h o had what has subsequently been described as the patellar " d u n k " syndrome (6). Two of the prostheses had loosened and
From the Department of Orthopaedic Surgery, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania.
Reprint requests: Brian J. Galinat,MD, Department of Orthopaedic Surgery, 1015 Walnut Street, Philadelphia,PA 19107.
required revision and 31% had evidence of radiolucency about the tibial component. Other studies of this total knee arthroplasty design have demonstrated similar results and complications (5, 13). Since 1984, 832 posterior stabilized condylar prostheses have been inserted at Pennsylvania Hospital. We detail the previously unreported complication of dislocation of this particular prosthesis.
Case Reports Case 1 A 64-year-old w o m a n had a right posterior stabilized total knee arthroplasty for progressive knee pain that became unresponsive to nonoperative management. A preoperative standing roentgenogram demonstrated a 16 ° valgus angulation (Fig. 1A). Her flexion arc was from 0 ° to 100 °, and no
364
The Journal of Arthroplasty Vol. 3 No. 4 December 1988
Fig. 1. Case 1, {A) Preoperative standing roentgenogram, showing 16° of vatgus angulation of the right knee. (B) Postoperative roentgenogram. (C} Lateral roentgenogram, documenting J3e posterior dislocation. (D} Lateral roentgenogram after reduction.
Posterior Stabilized Total Knee Dislocations
ligamentous laxity was noted. At surgery, the contracted lateral side required the release of the iliotibial band insertion, the popliteus, the lateral collateral origin, and the lateral patellar retinaculum. After the bony cuts were made, a 7.5-mm thick tibial plateau was found to provide appropriate soft tissue tension in flexion and extension. The patient's initial postoperative course was unremarkable. Roentgenograms revealed the leg to be well aligned in 7 ° of valgus (Fig. 1B). She had achieved motion from 0 ° to 100 ° by 6 weeks after surgery. Three months after surgery, early symptoms of the patellar "clunk" syndrome occurred (6). This progressed and was managed with arthroscopy 4 months after her total knee arthroplasty. She again regained excellent function and pain-free motion to 100 °. Eight months after operation, she presented to the emergency room stating that when getting out of bed, she felt a "pop" and was unable to move her knee because of pain. Further questioning revealed tha! at the time of the dislocation, her knee was flexed approximately 45 ° and the tibia was externally rotated. There was no neurovascular compromise.
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Roentgenograms documented the posterior dislocation (Fig. 1C). Reduction was accomplished by one person using longitudinal traction and extension to 20 ° while an anterior translation force was applied to the proximal tibia (Fig. 1D). Sedation was not required. The patient was maintained in a knee immobilizer full time for 1 month and then at night for 1 month. No redislocations have occurred in the 18 months since the reduction, and the patient has maintained motion from 0 ° to 100 °.
Case 2
A 73-year-old woman had a left posterior stabilized total knee arthroplasty for treatment of degenerative arthritis. A preoperative standing roentgenogram demonstrated a 30 ° valgus angulation (Fig. 2A). Her flexion arc was from 10° to 90 °. The valgus angulation was passively correctable to approximately 10°. At surgery, the contracted lateral side required the
Fig. 2. Case 2. (A) Preoperative standing roentgenogram, showing a 30° valgus angulation of the right knee. (B) Lateral roentgenogram, documenting the posterior dislocation.
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The Journal of Arthroplasty Vol. 3 No. 4 December 1988
release of the iliotibial band distally, the lateral collateral ligament and popliteus t e n d o n f r o m the femur, and the lateral patellar retinaculum. A 12.5m m tibial plateau thickness was f o u n d to provide good stability in flexion and extension. Postoperative roentgenograms revealed the leg to be in 8 ° of valgus. Shortly after discharge (1 m o n t h after operation) she sustained a posterior dislocation after externally rotating the tibia while the k n e e was flexed approximately 20 ° (Fig. 2B). There was n o neurovascular compromise. Reduction was easily accomplished with traction and application o f a n anterior translation force to the proximal tibia. T h e patient was maintained in a knee immobilizer for 1 month. No redislocations have occurred in the 18 m o n t h s since the reduction, and her flexion arc is from 5 ° to 110 °.
Discussion Dislocation of a total knee prosthesis is e x t r e m e l y u n c o m m o n . Published works by Insall m e n t i o n e d 4 cases of posterior subluxation of the tibia in 220 total condylar arthroplasties (7, 8). Before o p e r a t i o n , two of these had severe valgus deformities, o n e was n e u tral, and one was in 10 ° of varus. Two required revision, h o w e v e r n o specific details w e r e given w i t h regard to collateral ligament status or c o m p o n e n t positioning. A single case of total condylar k n e e dislocation presented by Bargren (1) was ascribed to malpositioning of the tibia] component. At revision, the tibial c o m p o n e n t was found to be directed at 30 ° medial to the tibia] tubercle. Of 94 knees requiring revision in a study b y Cameron (2), 3 had rotatory subluxation due to excessive internal rotation of the tibial c o m p o n e n t a n d two had anteroposterior instability. The sample p o p u l a tion was from a survey of 700 total k n e e arthroplasties, h o w e v e r no mention was m a d e of the type of arthroplasties used. A report of a dislocation of one s e m i c o n s t r a i n e d prosthesis that was inserted as a revision was recently presented by DenHartog (3). The design of this arthroplasty allows the retention of the p o s t e r i o r crnciate ligament. At the time of insertion, the cruciate ligaments were found to be nonfunctional. T h e author r e c o m m e n d e d using a posterior stabilized (cruciate replacement) prosthesis to p r e v e n t dislocation w h e n the posterior cruciate was absent. In our t w o cases, a posterior stabilized prosthesis was used. Both patients had valgus deformities re-
quiring e x t e n s i v e release of the contracted lateral soft tissues. T h e m e c h a n i s m of dislocation was one of slight flexion and external rotation. Reduction was easily a c c o m p l i s h e d with traction and anterior translation o n a slightly flexed knee. I n s p e c t i o n of a posterior stabilized total knee m o d e l reveals the femoral cam to be minimally restrained b y the tibial spine in the terminal 20 ° of extension. Excessive external rotation allows contact b e t w e e n the lateral aspect of the tibial spine and the medial aspect of the lateral femoral condyle. The fibial spine m a y t h e n lever o n this point to clear the cam, resulting in a posterior dislocation. W e r e c o m m e n d caution in performing the lateral soft tissue release required in the severe valgus knee. The release should provide balancing of the soft tissues w i t h the leg in an anatomic alignment. The soft tissue t e n s i o n should be clinically assessed in extension, 90 ° o f flexion, and 2 0 ° - 3 0 ° of flexion before a n y b o n y cuts are made. Medial and lateral soft tissue tension should be equivalent before the components are inserted. A lateral peripatellar approach is currently being evaluated in the severe valgus knee. This a p p r o a c h m a y allow improved exposure and more accurate m a n a g e m e n t of the contracted lateral soft tissues. It is h o p e d that these technique modifications will p r e v e n t further occurrences of this problem.
Acknowledgment The authors t h a n k A n n Louise Smith for her assistance in preparing the manuscript.
References 1. Bargren JH: Total knee dislocation due to rotatory malalignment of the tibial component: a case report. Clin Orthop 147:271, 1980 2. Cameron HU, Hunter GU: Failure in total knee arthroplasty. Clin Orthop 170:141, 1982 3. DenHartog BD, McQueen DA, Garcia GO: Traumatic posterior dislocation of a semiconstrained total knee arthroplasty: a case report. Contemp Orthop 15:41, 1987 4. Greenwald SA, Black JD, Matejczyk MB: Total knee replacement. AAOS Instruct Cour Lect 30:301, 1981 5. Figgie HE, Goldberg VM, Heiple KG et al: The influence of tibial-patellofemoral location on function of the knee in patients with the posterior stabilized condylar knee prosthesis. J Bone Joint Surg 68A:1035, 1986
Posterior Stabitized Total Knee DisIocations
6. Hozack WJ, Booth RE, Balderston RA, Rothmaa RH: The patellar "clunk" syndrome. Clin Orthop 231:79, 1988 7. Insall J, Scott WN, Ranawat C: The total condylar knee prosthesis: a report of two hundred and twenty cases. J Bone Joint Surg 61A:173, 1979 8. Insall JN, Hood RW, Flawn LB, Sullivan DJ: The total condylar knee prosthesis in gonarthrosis. J Bone Joint Surg 65A:619, 1983 9. Insa]l JN, Kelly M: The total condylar prosthesis. Clin Onhop 205:43, 1986
•
@alinat et el.
367
10. Insall JN, Lachiewicz PF, Burstein AH: The posterior stabilized condylar prosthesis: a modification of the total condylar design. J Bone Joint Surg 64A:1317, 1982 11. Laskin RS: Total condylar knee replacement in rheumatoid arthritis. J Bone Joint Surg 63A:29, 1985 12. Scott RD, Volatile TB: Twelve years experience with posterior cruciate retaining total knee arthroplasty. Clin Orthop 205:100, 1986 13. Scott WN, Rubinstein M: Posterior stabilized knee arthroplasty. Clin Or~hop 205:138, 1986