- Email: [email protected]
Stress Fracture of the Femoral Neck as a Complication of Total Knee Arthroplasty
The Journal of Arthroplasty Vol. 20 No. 3 2005
Case Report
Stress Fracture of the Femoral Neck as a Complication of Total Knee Arthroplasty Nayana Joshi, MD, PhD, Gemma Pidemunt, MD, Lluı´s Carrera, MD, PhD, and Antonio Navarro-Quilis, MD, PhD
Abstract: Stress fracture of the hip is a rare complication of total knee arthroplasty that occurs most often in patients in whom a significant deformity of the knee has been corrected, particularly those with poor mobility before surgery. We report 4 cases of ipsilateral fracture of the femoral neck after total knee arthroplasty. Key words: knee arthroplasty, stress fracture, subcapital fracture, osteoporosis, femoral fracture. n 2005 Elsevier Inc. All rights reserved.
bones in army recruits and athletes, in pathological bones of patients with rheumatoid arthritis or osteoporosis, and in patients receiving prolonged steroid treatment [10]. Due to changes in the weight-bearing axis of the extremity after TKA in patients with large deformities of the knee, the distraction forces concentrate at the superior cortex of the femoral neck. The loading on this weaker region may lead to a varus deformity that ends in fracture. This mainly occurs in patients with poor mobility and weakened bones. Patients that experience hip fracture after TKA fit into the group of those with pathological bones. In the present paper, we report 4 additional cases of ipsilateral fracture of the femoral neck after TKA.
The number of total knee arthroplasties (TKAs) performed each year continues to increase. With the advances in prosthesis design and new surgical techniques, TKA is now performed with excellent results, though associated complications still occur. Nowadays, approximately 5% to 10% of knees undergoing TKA will require revision within 10 to 15 years [1,2]. The most common indications for revision TKA are infection, mechanical loosening, and instability. Subcapital stress fracture of the femoral neck is uncommon. Stress fracture of the ipsilateral femoral neck is a rare complication after TKA, with only 16 cases reported in the English literature [3-10]. It has been described in normal
Case Reports From the Orthopedic Surgery Department, Hospital Universitari Vall d’Hebron, Barcelona, Spain. Submitted May 16, 2003; accepted June 17, 2004. No benefits or funds were received in support of the study. Reprint requests: Nayana Joshi, MD, PhD, Orthopedic Surgery Department, Hospital Universitari Vall d’Hebron, Sague´s 47, 1-2, 08021 Barcelona, Spain. n 2005 Elsevier Inc. All rights reserved. 0883-5403/04/2003-0020$30.00/0 doi:10.1016/j.arth.2004.09.044
Case 1 A 75-year-old woman with severe osteoarthritis of the left knee, a valgus deformity of 308, and a range of movement (ROM) of 808 flexion and 208 extension underwent rotating hinge knee arthroplasty (Endo-model; Waldemar Link, Hamburg,
392
Femoral Neck Fracture After Knee Arthroplasty ! Joshi et al 393
without previous trauma. The initial radiographs did not evidence fracture, but a repeated radiograph 1 week later revealed a displaced (Garden III) subcapital stress fracture of the ipsilateral femoral neck. The fracture was treated with cemented total hip arthroplasty (Autofit; Ortoimplant SA, MIL, Limoges, France). Case 2
Fig. 1. Rheumatoid arthritis of the left knee with a valgus deformity of 208.
Germany). Rehabilitation was started 48 hours after surgery. At 2 months postoperatively, the patient had a ROM of 908 flexion and 08 extension, she was pain free, and was able to walk on crutches with total weight bearing. Nine months after surgery, she complained of increasing groin pain
Fig. 2. Rotating hinge knee arthroplasty, anteroposterior view.
A 61-year-old man with rheumatoid arthritis and substantial deformity of both hands and knees was seen at our hospital. His knees had a valgus deformity of 208 and a ROM of 908 flexion and 108 extension (Fig. 1). The patient underwent rotating hinge knee arthroplasty (Endo-model, Waldemar Link) of the left knee (Fig. 2). Six months later, the patient was able to walk without crutches and the ROM of the knee was satisfactory. Thirteen months after the knee surgery, he presented with a 1-week history of an increasingly painful left hip at the emergency room, where radiographs showed a displaced (Garden IV) subcapital stress fracture of the ipsilateral femoral neck (Fig. 3). The fracture was treated with cemented total hip arthroplasty (Autofit, Ortoimplant SA, MIL) (Fig. 4). Case 3 A 70-year-old woman with severe osteoarthritis of the right knee, with a valgus deformity of 258,
Fig. 3. Displaced (Garden IV) subcapital stress fracture of the ipsilateral femoral neck, anteroposterior view.
394 The Journal of Arthroplasty Vol. 20 No. 3 April 2005 required reduction and internal fixation with a Dall-Miles plate.
Discussion
Fig. 4. Cemented total hip arthroplasty.
underwent rotating hinge knee arthroplasty (Endo-model, Waldemar Link). She was pain free and able to walk without crutches when, at 10 months postoperatively, she complained of groin pain. The radiographs revealed a nondisplaced (Garden II) subcapital stress fracture of the ipsilateral femoral neck. The fracture was reduced and internally fixed with cannulated hip screws. Two months later, she began weight bearing but developed severe groin pain due to non-union, and after 1 month, she underwent cemented total left hip arthroplasty (Autofit, Ortoimplant SA, MIL) because of groin pain. Case 4 A 78-year-old woman complained of increasing groin pain in the right hip 6 months after a right TKA (Endo-model, Waldemar Link) had been performed. (She had presented, before knee arthroplasty, with a valgus deformity of 178.) The radiographs revealed a displaced (Garden III) subcapital stress fracture of the ipsilateral femoral neck. This fracture was treated with hemiarthroplasty of the hip. Two months after surgery, she was able to walk painlessly with a crutch, but her physical activity was poor. Four years after the last surgery and after a slight trauma, she complained of pain and deformity in the right limb. Radiographs showed a periprosthetic fracture of the femur that
The coincidence of stress fracture of the femoral neck and TKA is uncommon. Stress fractures after TKA occur mainly in patients with considerable deformity of the knee and bone osteoporosis. Osteoporosis increases in elderly patients as their level of activity decreases because of the painful knee. The risk of fracture is directly related to the ratio of tissue stress to tissue strength, which in turn is dependent not only on tissue composition but also on tissue geometry and the direction and magnitude of loading [11]. The increased activity on osteoporotic bone and the changes in loading over the femoral neck due to the corrected axis of the knee after TKA may lead to stress fractures. However, although a large number of patients with significant knee deformity receive TKA after a period of inactivity with osteoporosis, the incidence of stress fractures after TKA is low. Thus, it seems that these factors can contribute to the development of stress fractures but are not crucial. In keeping with Rawes et al [7] and Hardy et al [6], we believe that changes in the biomechanical axis of the hip resulting from correction of large knee deformities are the most significant factor. We presume that the stress fracture occurred after correction of valgus knees because preoperatively, a valgus knee creates a situation in which the femoral neck has a valgus orientation compared to a neutrally-aligned leg. With the hip in valgus, the neck shaft angle is effectively reduced, and therefore, there is a decreased stress on the femoral neck. After correcting the valgus knee, the femoral neck is placed into varus. This increases the stresses on the femoral neck and would potentiate the risk of stress fracture. Constrained implants such as hinge prostheses combined with a pre-operative valgus deformity could be a harbinger for later stress fracture of the femoral neck. In addition to the femoral neck stress fractures, pubic stress fractures [12] and subtrochanteric stress fractures [13] have also been described. Individual study of the mechanism of the fracture is justified because the cause of ipsilateral subcapital stress fractures after TKA might be different in each case. These fractures are frequently missed on initial study; thus, when a patient who has been inactive for a long period complains of hip pain after TKA, the physician should be aware that the cause of pain may be stress fracture of the hip.
Femoral Neck Fracture After Knee Arthroplasty ! Joshi et al 395
Suspicion is warranted even when knee surgery was performed over a year before, because fractures can occur at a considerable interval after TKA, as in our case number 2. When the initial radiograph does not reveal a fracture, a bone scan is recommended to establish early diagnosis [6]. The cases presented were operated on between January 1993 and October 2000. Among the 104 primary rotating hinge arthroplasties (Endo-model, Waldemar Link) performed during this period at our hospital, 4 patients presented stress fractures of the ipsilateral femoral neck. This reflects a subcapital stress fracture rate of 3.8%. As compared with other series [5], our incidence is higher. Taking into account the fact that our 4 patients had very large knee deformities in valgus, gross osteoporosis, and had been inactive for a lengthy period, we consider that the incidence is not exceptional. Of the 16 cases described in the literature, approximately half had received hinge prostheses [4-10]. All of our patients underwent hinge prosthesis implantation. Theoretically, hinge designs alter knee kinematics and increase stress forces, concentrating stress at the tip of the stem or above it. This stress shielding around the stem may lead to significant osteopenia [14]. More studies are needed, however, to demonstrate that hinge prostheses play a part in the development of stress fractures. Although stress fracture of the femoral neck is uncommon, it should be suspected in patients complaining of hip pain who have undergone TKA, and particularly those with significant knee deformity, gross osteoporosis, and a long period of inactivity before TKA. Early diagnosis of subcapital fracture is important, but all effort should be directed toward its prevention. When correcting a severe valgus knee deformity, treatment of osteoporosis and close observation is necessary to prevent stress fracture of the femoral neck after TKA. It is doubtful if protective weight bearing would reduce stress fracture [5]. However, patients with gross osteoporosis would probably benefit from graduated weight bearing and exercises. By graduating weight bearing, treating osteoporosis, and using less constrained devices whenever
possible, stress fracture of the femoral neck may be avoided.
References 1. Maloney WJ. Aseptic failure in total knee arthroplasty. In: Engh GA, Rorabeck CH, editors. Revision total knee arthroplasty. Baltimore: Williams & Wilkins; 1997. p. 46. 2. Ranawat CS, Rodrı´guez JA. Malalignment and malrotation in total knee arthroplasty. In: Insall JN, Scott WN, Scuderi GR, editors. Current concepts in primary and revision total knee arthroplasty. Philadelphia: Lippincott-Raven Publishers; 1996. p. 115. 3. Rand JA, Coventry MB. Stress fractures after total knee replacement. J Bone Joint Surg Am 1980; 62:226. 4. Lesniewski PJ, Testa NN. Stress fracture of the hip as a complication of total knee replacement. J Bone Joint Surg Am 1982;64:304. 5. Mc Elwaine JP, Sheehan JM. Spontaneous fractures of the femoral neck after total replacement of the knee. J Bone Joint Surg Br 1982;64:323. 6. Hardy DCR, Delince PE, Yasik E, et al. Stress fracture of the hip. Clin Orthop 1992;281:140. 7. Rawes ML, Patsalis T, Gregg PJ. Subcapital stress fractures of the hip complicating total knee replacement. Injury 1995;26:421. 8. Fipp G. Stress fractures of the femoral neck following total knee arthroplasty. J Arthroplasty 1988;3:347. 9. Palanca Martin D, Albareda J, Seral F. Subcapital stress fracture of the femoral neck after total knee arthroplasty. Int Orthop 1994;18:308. 10. Hendel D, Beloosesky Y, Weisbort M. Fracture of the hip after knee arthroplasty—an unusual case with pain in the knee. Acta Orthop Scand 2001;72:194. 11. Lotz JC, Cheal EJ, Hayes WC. Stress distributions within the proximal femur during gait and falls: implications for osteoporotic fracture. Osteoporos Int 1995;5:252. 12. Smith MO, Henko JA. Pubic ramus fatigue fractures after total knee arthroplasty. Orthopedics 1988; 11:315. 13. Kumm DA, Rack C, Rutt J. Subtrochanteric stress fracture of the femur following total knee arthroplasty. J Arthroplasty 1997;12:580. 14. Whaley AL, Trousdale RT, Hanssen AD, et al. Cemented long-stem revision total knee arthroplasty at 10-years follow-up. Presented at the Annual Meeting of the American Academy of Orthopaedic Surgeons, Orlando, FL. March 2000.
Case Report
Stress Fracture of the Femoral Neck as a Complication of Total Knee Arthroplasty Nayana Joshi, MD, PhD, Gemma Pidemunt, MD, Lluı´s Carrera, MD, PhD, and Antonio Navarro-Quilis, MD, PhD
Abstract: Stress fracture of the hip is a rare complication of total knee arthroplasty that occurs most often in patients in whom a significant deformity of the knee has been corrected, particularly those with poor mobility before surgery. We report 4 cases of ipsilateral fracture of the femoral neck after total knee arthroplasty. Key words: knee arthroplasty, stress fracture, subcapital fracture, osteoporosis, femoral fracture. n 2005 Elsevier Inc. All rights reserved.
bones in army recruits and athletes, in pathological bones of patients with rheumatoid arthritis or osteoporosis, and in patients receiving prolonged steroid treatment [10]. Due to changes in the weight-bearing axis of the extremity after TKA in patients with large deformities of the knee, the distraction forces concentrate at the superior cortex of the femoral neck. The loading on this weaker region may lead to a varus deformity that ends in fracture. This mainly occurs in patients with poor mobility and weakened bones. Patients that experience hip fracture after TKA fit into the group of those with pathological bones. In the present paper, we report 4 additional cases of ipsilateral fracture of the femoral neck after TKA.
The number of total knee arthroplasties (TKAs) performed each year continues to increase. With the advances in prosthesis design and new surgical techniques, TKA is now performed with excellent results, though associated complications still occur. Nowadays, approximately 5% to 10% of knees undergoing TKA will require revision within 10 to 15 years [1,2]. The most common indications for revision TKA are infection, mechanical loosening, and instability. Subcapital stress fracture of the femoral neck is uncommon. Stress fracture of the ipsilateral femoral neck is a rare complication after TKA, with only 16 cases reported in the English literature [3-10]. It has been described in normal
Case Reports From the Orthopedic Surgery Department, Hospital Universitari Vall d’Hebron, Barcelona, Spain. Submitted May 16, 2003; accepted June 17, 2004. No benefits or funds were received in support of the study. Reprint requests: Nayana Joshi, MD, PhD, Orthopedic Surgery Department, Hospital Universitari Vall d’Hebron, Sague´s 47, 1-2, 08021 Barcelona, Spain. n 2005 Elsevier Inc. All rights reserved. 0883-5403/04/2003-0020$30.00/0 doi:10.1016/j.arth.2004.09.044
Case 1 A 75-year-old woman with severe osteoarthritis of the left knee, a valgus deformity of 308, and a range of movement (ROM) of 808 flexion and 208 extension underwent rotating hinge knee arthroplasty (Endo-model; Waldemar Link, Hamburg,
392
Femoral Neck Fracture After Knee Arthroplasty ! Joshi et al 393
without previous trauma. The initial radiographs did not evidence fracture, but a repeated radiograph 1 week later revealed a displaced (Garden III) subcapital stress fracture of the ipsilateral femoral neck. The fracture was treated with cemented total hip arthroplasty (Autofit; Ortoimplant SA, MIL, Limoges, France). Case 2
Fig. 1. Rheumatoid arthritis of the left knee with a valgus deformity of 208.
Germany). Rehabilitation was started 48 hours after surgery. At 2 months postoperatively, the patient had a ROM of 908 flexion and 08 extension, she was pain free, and was able to walk on crutches with total weight bearing. Nine months after surgery, she complained of increasing groin pain
Fig. 2. Rotating hinge knee arthroplasty, anteroposterior view.
A 61-year-old man with rheumatoid arthritis and substantial deformity of both hands and knees was seen at our hospital. His knees had a valgus deformity of 208 and a ROM of 908 flexion and 108 extension (Fig. 1). The patient underwent rotating hinge knee arthroplasty (Endo-model, Waldemar Link) of the left knee (Fig. 2). Six months later, the patient was able to walk without crutches and the ROM of the knee was satisfactory. Thirteen months after the knee surgery, he presented with a 1-week history of an increasingly painful left hip at the emergency room, where radiographs showed a displaced (Garden IV) subcapital stress fracture of the ipsilateral femoral neck (Fig. 3). The fracture was treated with cemented total hip arthroplasty (Autofit, Ortoimplant SA, MIL) (Fig. 4). Case 3 A 70-year-old woman with severe osteoarthritis of the right knee, with a valgus deformity of 258,
Fig. 3. Displaced (Garden IV) subcapital stress fracture of the ipsilateral femoral neck, anteroposterior view.
394 The Journal of Arthroplasty Vol. 20 No. 3 April 2005 required reduction and internal fixation with a Dall-Miles plate.
Discussion
Fig. 4. Cemented total hip arthroplasty.
underwent rotating hinge knee arthroplasty (Endo-model, Waldemar Link). She was pain free and able to walk without crutches when, at 10 months postoperatively, she complained of groin pain. The radiographs revealed a nondisplaced (Garden II) subcapital stress fracture of the ipsilateral femoral neck. The fracture was reduced and internally fixed with cannulated hip screws. Two months later, she began weight bearing but developed severe groin pain due to non-union, and after 1 month, she underwent cemented total left hip arthroplasty (Autofit, Ortoimplant SA, MIL) because of groin pain. Case 4 A 78-year-old woman complained of increasing groin pain in the right hip 6 months after a right TKA (Endo-model, Waldemar Link) had been performed. (She had presented, before knee arthroplasty, with a valgus deformity of 178.) The radiographs revealed a displaced (Garden III) subcapital stress fracture of the ipsilateral femoral neck. This fracture was treated with hemiarthroplasty of the hip. Two months after surgery, she was able to walk painlessly with a crutch, but her physical activity was poor. Four years after the last surgery and after a slight trauma, she complained of pain and deformity in the right limb. Radiographs showed a periprosthetic fracture of the femur that
The coincidence of stress fracture of the femoral neck and TKA is uncommon. Stress fractures after TKA occur mainly in patients with considerable deformity of the knee and bone osteoporosis. Osteoporosis increases in elderly patients as their level of activity decreases because of the painful knee. The risk of fracture is directly related to the ratio of tissue stress to tissue strength, which in turn is dependent not only on tissue composition but also on tissue geometry and the direction and magnitude of loading [11]. The increased activity on osteoporotic bone and the changes in loading over the femoral neck due to the corrected axis of the knee after TKA may lead to stress fractures. However, although a large number of patients with significant knee deformity receive TKA after a period of inactivity with osteoporosis, the incidence of stress fractures after TKA is low. Thus, it seems that these factors can contribute to the development of stress fractures but are not crucial. In keeping with Rawes et al [7] and Hardy et al [6], we believe that changes in the biomechanical axis of the hip resulting from correction of large knee deformities are the most significant factor. We presume that the stress fracture occurred after correction of valgus knees because preoperatively, a valgus knee creates a situation in which the femoral neck has a valgus orientation compared to a neutrally-aligned leg. With the hip in valgus, the neck shaft angle is effectively reduced, and therefore, there is a decreased stress on the femoral neck. After correcting the valgus knee, the femoral neck is placed into varus. This increases the stresses on the femoral neck and would potentiate the risk of stress fracture. Constrained implants such as hinge prostheses combined with a pre-operative valgus deformity could be a harbinger for later stress fracture of the femoral neck. In addition to the femoral neck stress fractures, pubic stress fractures [12] and subtrochanteric stress fractures [13] have also been described. Individual study of the mechanism of the fracture is justified because the cause of ipsilateral subcapital stress fractures after TKA might be different in each case. These fractures are frequently missed on initial study; thus, when a patient who has been inactive for a long period complains of hip pain after TKA, the physician should be aware that the cause of pain may be stress fracture of the hip.
Femoral Neck Fracture After Knee Arthroplasty ! Joshi et al 395
Suspicion is warranted even when knee surgery was performed over a year before, because fractures can occur at a considerable interval after TKA, as in our case number 2. When the initial radiograph does not reveal a fracture, a bone scan is recommended to establish early diagnosis [6]. The cases presented were operated on between January 1993 and October 2000. Among the 104 primary rotating hinge arthroplasties (Endo-model, Waldemar Link) performed during this period at our hospital, 4 patients presented stress fractures of the ipsilateral femoral neck. This reflects a subcapital stress fracture rate of 3.8%. As compared with other series [5], our incidence is higher. Taking into account the fact that our 4 patients had very large knee deformities in valgus, gross osteoporosis, and had been inactive for a lengthy period, we consider that the incidence is not exceptional. Of the 16 cases described in the literature, approximately half had received hinge prostheses [4-10]. All of our patients underwent hinge prosthesis implantation. Theoretically, hinge designs alter knee kinematics and increase stress forces, concentrating stress at the tip of the stem or above it. This stress shielding around the stem may lead to significant osteopenia [14]. More studies are needed, however, to demonstrate that hinge prostheses play a part in the development of stress fractures. Although stress fracture of the femoral neck is uncommon, it should be suspected in patients complaining of hip pain who have undergone TKA, and particularly those with significant knee deformity, gross osteoporosis, and a long period of inactivity before TKA. Early diagnosis of subcapital fracture is important, but all effort should be directed toward its prevention. When correcting a severe valgus knee deformity, treatment of osteoporosis and close observation is necessary to prevent stress fracture of the femoral neck after TKA. It is doubtful if protective weight bearing would reduce stress fracture [5]. However, patients with gross osteoporosis would probably benefit from graduated weight bearing and exercises. By graduating weight bearing, treating osteoporosis, and using less constrained devices whenever
possible, stress fracture of the femoral neck may be avoided.
References 1. Maloney WJ. Aseptic failure in total knee arthroplasty. In: Engh GA, Rorabeck CH, editors. Revision total knee arthroplasty. Baltimore: Williams & Wilkins; 1997. p. 46. 2. Ranawat CS, Rodrı´guez JA. Malalignment and malrotation in total knee arthroplasty. In: Insall JN, Scott WN, Scuderi GR, editors. Current concepts in primary and revision total knee arthroplasty. Philadelphia: Lippincott-Raven Publishers; 1996. p. 115. 3. Rand JA, Coventry MB. Stress fractures after total knee replacement. J Bone Joint Surg Am 1980; 62:226. 4. Lesniewski PJ, Testa NN. Stress fracture of the hip as a complication of total knee replacement. J Bone Joint Surg Am 1982;64:304. 5. Mc Elwaine JP, Sheehan JM. Spontaneous fractures of the femoral neck after total replacement of the knee. J Bone Joint Surg Br 1982;64:323. 6. Hardy DCR, Delince PE, Yasik E, et al. Stress fracture of the hip. Clin Orthop 1992;281:140. 7. Rawes ML, Patsalis T, Gregg PJ. Subcapital stress fractures of the hip complicating total knee replacement. Injury 1995;26:421. 8. Fipp G. Stress fractures of the femoral neck following total knee arthroplasty. J Arthroplasty 1988;3:347. 9. Palanca Martin D, Albareda J, Seral F. Subcapital stress fracture of the femoral neck after total knee arthroplasty. Int Orthop 1994;18:308. 10. Hendel D, Beloosesky Y, Weisbort M. Fracture of the hip after knee arthroplasty—an unusual case with pain in the knee. Acta Orthop Scand 2001;72:194. 11. Lotz JC, Cheal EJ, Hayes WC. Stress distributions within the proximal femur during gait and falls: implications for osteoporotic fracture. Osteoporos Int 1995;5:252. 12. Smith MO, Henko JA. Pubic ramus fatigue fractures after total knee arthroplasty. Orthopedics 1988; 11:315. 13. Kumm DA, Rack C, Rutt J. Subtrochanteric stress fracture of the femur following total knee arthroplasty. J Arthroplasty 1997;12:580. 14. Whaley AL, Trousdale RT, Hanssen AD, et al. Cemented long-stem revision total knee arthroplasty at 10-years follow-up. Presented at the Annual Meeting of the American Academy of Orthopaedic Surgeons, Orlando, FL. March 2000.