Knee Surg Sports Traumatol Arthrosc DOI 10.1007/s00167-014-3459-6
KNEE
Medial femoral condyle fracture as an intraoperative complication of Oxford unicompartmental knee replacement Bart ten Brinke · Laurens J. de Haan · Koen L. M. Koenraadt · Rutger C. I. van Geenen
Received: 30 June 2014 / Accepted: 20 November 2014 © European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2014
Abstract Oxford unicompartmental knee replacement (OUKR) is associated with a low perioperative complication rate. This case report describes a periprosthetic fracture of the medial femoral condyle that occurred during an OUKR. The patient was treated with a non-weightbearing long leg cast for 6 weeks. Afterwards, the fracture had healed, and 3 months postoperatively, there was a full range of motion. Factors leading to this complication could be the impaction force or direction, or a diminished load resistance of the distal femur. Minimally displaced coronal periprosthetic fractures after OUKR can be managed conservatively without residual functional impairment. Level of evidence Case report, Level IV.
perioperative complication rate. [10] The most important complications are aseptic loosening (0.25–1.4 %), polyethylene dislocation (0.4–3 %), unexplained pain (0.5–1.6 %), infection (0.25–3 %) and periprosthetic fractures (0.1 %) [4, 5, 9, 14]. Periprosthetic fractures are most common in the tibial plateau and occur mostly during surgery [13]. To our knowledge, only one supracondylar periprosthetic fracture has been reported during unicompartmental knee arthroplasty [10]. This case report describes a periprosthetic fracture of the medial femoral condyle as an intraoperative complication during OUKR. Knowledge of the fracture mechanism and the treatment options could help to prevent this complication and optimize the treatment.
Keywords Unicompartmental knee replacement · Complication · Knee arthroplasty · Conservative treatment Case report Introduction In the last two decades, Oxford unicompartmental knee replacement (OUKR) has become an accepted procedure for anteromedial osteoarthritis of the knee with good long-term results in experienced hands [5, 6, 11, 12, 15]. OUKR is a safe procedure and is associated with a low
B. ten Brinke (*) · L. J. de Haan · R. C. I. van Geenen Department of Orthopaedic Surgery, Amphia Ziekenhuis, Molengracht 21, P.O. Box 90158, 4800 RK Breda, The Netherlands e-mail: [email protected] K. L. M. Koenraadt Department of Orthopaedic Surgery, Orthopedic Knowledge Center, Amphia Ziekenhuis, Molengracht 21, P.O. Box 90158, 4800 RK Breda, The Netherlands
A 63-year-old woman with symptomatic anteromedial osteoarthritis of the left knee, confirmed by stress radiographs, received an OUKR by an experienced orthopaedic surgeon [3]. The procedure was performed according to the Oxford surgical technique guidelines using Microplasty instrumentation and a 500-g hammer. During surgery, no remarkable findings were noticed. Directly after surgery, a minimally displaced coronal fracture of the medial condyle (i.e. a Hoffa fracture) was seen on the lateral radiographs (Fig. 1b). The patient was treated conservatively with a non-weight-bearing long leg cast for 6 weeks with the knee in 10° of flexion without valgus or varus stress. To exclude osteoporosis, a bone mineral density test was performed, which revealed a T-score of −1.3. One week after surgery, radiographs were taken and no displacement was seen. After 6 weeks, the radiographs showed fracture union. We removed the cast, and the patient
13
Knee Surg Sports Traumatol Arthrosc
Fig. 1 Anteroposterior (a) and lateral (b) radiographs of the minimally displaced medial femoral condyle fracture, directly after Oxford Unicompartmental knee replacement
started physiotherapy with full weight-bearing mobilization, strength exercises and passive range of motion exercises. Twelve weeks after surgery, the patient could walk independently with a flexion of 130° and no extension lag. The surgical procedure and the treatment of the complication are routine procedures for which, according to the Dutch law, IRB approval was not needed.
Discussion The current case study describes the finding of a periprosthetic fracture of the medial femoral condyle as an intraoperative complication during OUKR. Only two cases of periprosthetic fractures of the medial femoral condyle were previously reported [1, 7]. These two fractures occurred, respectively, 1 and 3 years after placement of the prosthesis. However, to our knowledge, no cases have been reported in the literature of such a fracture as an intraoperative complication of OUKR. Factors that might contribute to periprosthetic femoral condyle fracture are the strength of the distal femur and the impaction technique. During preparation of the distal femur, osteophytes are removed from the medial, lateral and posterior border. Furthermore, the anterior cortex is reamed to prevent anterior impingement. This subtotal circular decorticalization might diminish the structural strength of the distal femur. In addition, osteoporosis might play a role in
13
Fig. 2 Slightly ventrally directed impaction angle resulting in an impaction force in line with the medial condyle
the strength of the distal femur. However, the bone mineral density test revealed no osteoporosis in this patient. Besides the diminished strength of the distal femur, the impaction technique might have played a role. As described in the instructional guide, the direction of the impaction force is in line with the femoral condyle (Fig. 2). Although this facilitates sliding of the pegs into the bone, this could also create a shear force on the medial condyle, especially if the forces are directed more dorsally (Fig. 3). A vertical shear force to a flexed knee is known as the usual mechanism of injury of coronal plane fractures of the femoral condyle in high-energy trauma [2]. This mechanism might also have contributed to
Knee Surg Sports Traumatol Arthrosc
after OUKR can be treated conservatively with non-weightbearing mobilization for 6 weeks with the knee in extension, without residual functional impairment. Acknowledgments The authors would like to thank Mr. J.P. de Goffau who made the illustrations of this manuscript. Conflict of interest The authors declare that they have no conflict of interest.
References
Fig. 3 Dorsally directed impaction angle resulting in a shear force on the medial condyle
the fracture pattern seen in this case report. Furthermore, the size of the impaction force is of great importance. If a toffee hammer is not available, a regular hammer can be used. This creates a large impaction force that could have contributed to this fracture. Hence, both the diminished strength of the distal femur as a result of the circular decorticalization as well as the direction and size of the impaction force might have played a role in causing the fracture. However, although different factors might have contributed to the intraoperative fracture, the actual cause of the fracture remains unknown. A recent review of Arastu et al. [2] revealed that surgical fixation is the best treatment option for coronal plane femoral condyle fractures, since non-operative treatment has been associated with poor outcomes. In 1989, Lewis et al. [8]. described three patients who were treated non-operatively, with subsequent displacement of the fracture and poor outcomes. However, all these cases were associated with trauma and major forces were involved. No recent literature is available about the outcome of conservative treatment of nontraumatic, minimally displaced coronal plane fractures of the femoral condyle. Therefore, in this non-traumatic case with a minimally displaced fracture, we decided for conservative treatment in extension with non-weight-bearing mobilization for 6 weeks. This approach resulted in fracture healing and a normal range of motion after 12 weeks. As a result of this case, more care is taken to impact the femoral component in the correct directions and a toffee hammer is always used. Furthermore, in case of an undisplaced fracture, conservative treatment in a long leg cast results in a well-functioning OUKR.
Conclusion Medial condyle fractures can occur during OUKR. Minimally displaced fractures of the medial femoral condyle
1. Akan B, Yildirim T, Karaguven D (2013) Medial femoral condyle fracture after cementless unicompartmental knee replacement: a rare complication. Knee 20(4):295–297 2. Arastu MH, Kokke MC, Duffy PJ, Korley REC, Buckley RE (2013) Coronal plane partial articular fractures of the distal femoral condyle current concepts in management. Bone Joint J 95(9):1165–1171 3. Baker P, Jameson S, Critchley R, Reed M, Gregg P, Deehan D (2013) Center and surgeon volume influence the revision rate following unicondylar knee replacement: an analysis of 23,400 medial cemented unicondylar knee replacements. J Bone Joint Surg Am 95(8):702–709 4. Dervin GF, Carruthers C, Feibel RJ, Biachino AA, Kim PR, Thurston PR (2011) Initial experience with the oxford unicompartmental knee arthroplasty. J Arthroplasty 26(2):192–197 5. Faour-Martín O, Valverde-García JA, Martín-Ferrero MA, VegaCastrillo A, de la Red Gallego MA, Suárez de Puga CC, AmigoLiñares L (2013) Oxford phase 3 unicondylar knee arthroplasty through a minimally invasive approach: long-term results. Int Orthop 37(5):833–838 6. Kim KT, Lee S, Park HS, Cho KH, Kim KS (2007) A prospective analysis of Oxford phase 3 unicompartmental knee arthroplasty. Orthopedics 30(5):15–18 7. Kim KT, Lee S, Cho KH, Kim KS (2009) Fracture of the medial femoral condyle after unicompartmental knee arthroplasty. J Arthroplasty 24(7):1143 8. Lewis SL, Pozo JL, Muirhead-Allwood WF (1989) Coronal fractures of the lateral femoral condyle. J Bone Joint Surg Br 71(1):118–120 9. Lim HC, Bae JH, Song SH, Kim SJ (2012) Oxford phase 3 unicompartmental knee replacement in Korean patients. J Bone Joint Surg Br 94(8):1071–1076 10. Morris MJ, Molli RG, Berend KR, Lombardi AV Jr (2013) Mortality and perioperative complications after unicomparmental knee arthroplasty. Knee 20(3):218–220 11. Murray DW, Goodfellow JW, O’Connor JJ (1998) The Oxford medial unicompartmental arthroplasty: a ten year survival study. J Bone Joint Surg Br 80(6):983–989 12. Murray DW (2005) Mobile bearing unicompartmental knee replacement. Orthopedics 28(9):985–987 13. Pandit H, Murray DW, Dodd CA, Deo S, Waite J, Goodfellow J, Gibbons CL (2007) Medial tibial plateau fracture and the Oxford unicompartmental knee. Orthopedics. 30(5):28–31 14. Price AJ, Waite JC, Svard U (2005) Long-term clinical results of the medial Oxford unicompartmental knee arthroplasty. Clin Orthop Relat Res 435:171–180 15. Svard UC, Price AJ (2001) Oxford medial unicompartmental knee arthroplasty. A survival analysis of an independent series. J Bone Joint Surg Br 83(2):191–194
13
KNEE
Medial femoral condyle fracture as an intraoperative complication of Oxford unicompartmental knee replacement Bart ten Brinke · Laurens J. de Haan · Koen L. M. Koenraadt · Rutger C. I. van Geenen
Received: 30 June 2014 / Accepted: 20 November 2014 © European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2014
Abstract Oxford unicompartmental knee replacement (OUKR) is associated with a low perioperative complication rate. This case report describes a periprosthetic fracture of the medial femoral condyle that occurred during an OUKR. The patient was treated with a non-weightbearing long leg cast for 6 weeks. Afterwards, the fracture had healed, and 3 months postoperatively, there was a full range of motion. Factors leading to this complication could be the impaction force or direction, or a diminished load resistance of the distal femur. Minimally displaced coronal periprosthetic fractures after OUKR can be managed conservatively without residual functional impairment. Level of evidence Case report, Level IV.
perioperative complication rate. [10] The most important complications are aseptic loosening (0.25–1.4 %), polyethylene dislocation (0.4–3 %), unexplained pain (0.5–1.6 %), infection (0.25–3 %) and periprosthetic fractures (0.1 %) [4, 5, 9, 14]. Periprosthetic fractures are most common in the tibial plateau and occur mostly during surgery [13]. To our knowledge, only one supracondylar periprosthetic fracture has been reported during unicompartmental knee arthroplasty [10]. This case report describes a periprosthetic fracture of the medial femoral condyle as an intraoperative complication during OUKR. Knowledge of the fracture mechanism and the treatment options could help to prevent this complication and optimize the treatment.
Keywords Unicompartmental knee replacement · Complication · Knee arthroplasty · Conservative treatment Case report Introduction In the last two decades, Oxford unicompartmental knee replacement (OUKR) has become an accepted procedure for anteromedial osteoarthritis of the knee with good long-term results in experienced hands [5, 6, 11, 12, 15]. OUKR is a safe procedure and is associated with a low
B. ten Brinke (*) · L. J. de Haan · R. C. I. van Geenen Department of Orthopaedic Surgery, Amphia Ziekenhuis, Molengracht 21, P.O. Box 90158, 4800 RK Breda, The Netherlands e-mail: [email protected] K. L. M. Koenraadt Department of Orthopaedic Surgery, Orthopedic Knowledge Center, Amphia Ziekenhuis, Molengracht 21, P.O. Box 90158, 4800 RK Breda, The Netherlands
A 63-year-old woman with symptomatic anteromedial osteoarthritis of the left knee, confirmed by stress radiographs, received an OUKR by an experienced orthopaedic surgeon [3]. The procedure was performed according to the Oxford surgical technique guidelines using Microplasty instrumentation and a 500-g hammer. During surgery, no remarkable findings were noticed. Directly after surgery, a minimally displaced coronal fracture of the medial condyle (i.e. a Hoffa fracture) was seen on the lateral radiographs (Fig. 1b). The patient was treated conservatively with a non-weight-bearing long leg cast for 6 weeks with the knee in 10° of flexion without valgus or varus stress. To exclude osteoporosis, a bone mineral density test was performed, which revealed a T-score of −1.3. One week after surgery, radiographs were taken and no displacement was seen. After 6 weeks, the radiographs showed fracture union. We removed the cast, and the patient
13
Knee Surg Sports Traumatol Arthrosc
Fig. 1 Anteroposterior (a) and lateral (b) radiographs of the minimally displaced medial femoral condyle fracture, directly after Oxford Unicompartmental knee replacement
started physiotherapy with full weight-bearing mobilization, strength exercises and passive range of motion exercises. Twelve weeks after surgery, the patient could walk independently with a flexion of 130° and no extension lag. The surgical procedure and the treatment of the complication are routine procedures for which, according to the Dutch law, IRB approval was not needed.
Discussion The current case study describes the finding of a periprosthetic fracture of the medial femoral condyle as an intraoperative complication during OUKR. Only two cases of periprosthetic fractures of the medial femoral condyle were previously reported [1, 7]. These two fractures occurred, respectively, 1 and 3 years after placement of the prosthesis. However, to our knowledge, no cases have been reported in the literature of such a fracture as an intraoperative complication of OUKR. Factors that might contribute to periprosthetic femoral condyle fracture are the strength of the distal femur and the impaction technique. During preparation of the distal femur, osteophytes are removed from the medial, lateral and posterior border. Furthermore, the anterior cortex is reamed to prevent anterior impingement. This subtotal circular decorticalization might diminish the structural strength of the distal femur. In addition, osteoporosis might play a role in
13
Fig. 2 Slightly ventrally directed impaction angle resulting in an impaction force in line with the medial condyle
the strength of the distal femur. However, the bone mineral density test revealed no osteoporosis in this patient. Besides the diminished strength of the distal femur, the impaction technique might have played a role. As described in the instructional guide, the direction of the impaction force is in line with the femoral condyle (Fig. 2). Although this facilitates sliding of the pegs into the bone, this could also create a shear force on the medial condyle, especially if the forces are directed more dorsally (Fig. 3). A vertical shear force to a flexed knee is known as the usual mechanism of injury of coronal plane fractures of the femoral condyle in high-energy trauma [2]. This mechanism might also have contributed to
Knee Surg Sports Traumatol Arthrosc
after OUKR can be treated conservatively with non-weightbearing mobilization for 6 weeks with the knee in extension, without residual functional impairment. Acknowledgments The authors would like to thank Mr. J.P. de Goffau who made the illustrations of this manuscript. Conflict of interest The authors declare that they have no conflict of interest.
References
Fig. 3 Dorsally directed impaction angle resulting in a shear force on the medial condyle
the fracture pattern seen in this case report. Furthermore, the size of the impaction force is of great importance. If a toffee hammer is not available, a regular hammer can be used. This creates a large impaction force that could have contributed to this fracture. Hence, both the diminished strength of the distal femur as a result of the circular decorticalization as well as the direction and size of the impaction force might have played a role in causing the fracture. However, although different factors might have contributed to the intraoperative fracture, the actual cause of the fracture remains unknown. A recent review of Arastu et al. [2] revealed that surgical fixation is the best treatment option for coronal plane femoral condyle fractures, since non-operative treatment has been associated with poor outcomes. In 1989, Lewis et al. [8]. described three patients who were treated non-operatively, with subsequent displacement of the fracture and poor outcomes. However, all these cases were associated with trauma and major forces were involved. No recent literature is available about the outcome of conservative treatment of nontraumatic, minimally displaced coronal plane fractures of the femoral condyle. Therefore, in this non-traumatic case with a minimally displaced fracture, we decided for conservative treatment in extension with non-weight-bearing mobilization for 6 weeks. This approach resulted in fracture healing and a normal range of motion after 12 weeks. As a result of this case, more care is taken to impact the femoral component in the correct directions and a toffee hammer is always used. Furthermore, in case of an undisplaced fracture, conservative treatment in a long leg cast results in a well-functioning OUKR.
Conclusion Medial condyle fractures can occur during OUKR. Minimally displaced fractures of the medial femoral condyle
1. Akan B, Yildirim T, Karaguven D (2013) Medial femoral condyle fracture after cementless unicompartmental knee replacement: a rare complication. Knee 20(4):295–297 2. Arastu MH, Kokke MC, Duffy PJ, Korley REC, Buckley RE (2013) Coronal plane partial articular fractures of the distal femoral condyle current concepts in management. Bone Joint J 95(9):1165–1171 3. Baker P, Jameson S, Critchley R, Reed M, Gregg P, Deehan D (2013) Center and surgeon volume influence the revision rate following unicondylar knee replacement: an analysis of 23,400 medial cemented unicondylar knee replacements. J Bone Joint Surg Am 95(8):702–709 4. Dervin GF, Carruthers C, Feibel RJ, Biachino AA, Kim PR, Thurston PR (2011) Initial experience with the oxford unicompartmental knee arthroplasty. J Arthroplasty 26(2):192–197 5. Faour-Martín O, Valverde-García JA, Martín-Ferrero MA, VegaCastrillo A, de la Red Gallego MA, Suárez de Puga CC, AmigoLiñares L (2013) Oxford phase 3 unicondylar knee arthroplasty through a minimally invasive approach: long-term results. Int Orthop 37(5):833–838 6. Kim KT, Lee S, Park HS, Cho KH, Kim KS (2007) A prospective analysis of Oxford phase 3 unicompartmental knee arthroplasty. Orthopedics 30(5):15–18 7. Kim KT, Lee S, Cho KH, Kim KS (2009) Fracture of the medial femoral condyle after unicompartmental knee arthroplasty. J Arthroplasty 24(7):1143 8. Lewis SL, Pozo JL, Muirhead-Allwood WF (1989) Coronal fractures of the lateral femoral condyle. J Bone Joint Surg Br 71(1):118–120 9. Lim HC, Bae JH, Song SH, Kim SJ (2012) Oxford phase 3 unicompartmental knee replacement in Korean patients. J Bone Joint Surg Br 94(8):1071–1076 10. Morris MJ, Molli RG, Berend KR, Lombardi AV Jr (2013) Mortality and perioperative complications after unicomparmental knee arthroplasty. Knee 20(3):218–220 11. Murray DW, Goodfellow JW, O’Connor JJ (1998) The Oxford medial unicompartmental arthroplasty: a ten year survival study. J Bone Joint Surg Br 80(6):983–989 12. Murray DW (2005) Mobile bearing unicompartmental knee replacement. Orthopedics 28(9):985–987 13. Pandit H, Murray DW, Dodd CA, Deo S, Waite J, Goodfellow J, Gibbons CL (2007) Medial tibial plateau fracture and the Oxford unicompartmental knee. Orthopedics. 30(5):28–31 14. Price AJ, Waite JC, Svard U (2005) Long-term clinical results of the medial Oxford unicompartmental knee arthroplasty. Clin Orthop Relat Res 435:171–180 15. Svard UC, Price AJ (2001) Oxford medial unicompartmental knee arthroplasty. A survival analysis of an independent series. J Bone Joint Surg Br 83(2):191–194
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