Patients with arthritis of the knee and an extra-articular deformity present a unique technical challenge, as it becomes more difficult to restore the mechanical axis during total knee replacement (TKR). Current treatment options include a 2-stage procedure in which an extra-articular correctional osteotomy is performed several months before the primary TKR, a 1-stage procedure in which an extra-articular correctional osteotomy is performed at the time of the index TKR, or a 1-stage procedure in which TKR is performed with correction of the extra-articular deformity.
One-stage TKR with intra-articular correction of the extra-articular deformity is our treatment of choice. With proper planning, appropriate bone cuts to restore alignment, and the necessary soft tissue releases to balance the knee in flexion and extension, a satisfactory TKR can be achieved.
Two patients with arthritis and a severe extra-articular deformity (varus/valgus deformity >20°, recurvatum and malunion of a tibial or femoral fracture) were treated with 1-stage TKR with intra-articular correction of the extra-articular deformity. The technique followed had been successfully performed in 15 previous cases. The procedure was clinically successful in both patients without complications. At 2-year follow-up, Knee Society Scores improved from 40 to 95 and there was no evidence of instability in either case.
Total knee replacement (TKR) is one of the most successful procedures for relieving pain and restoring function in patients with arthritis of the knee. However, patients with arthritis and an extra-articular deformity present a unique technical challenge, as it becomes more difficult to restore the mechanical axis during TKR (Figure 1). While an extra-articular deformity is typically the result of a femoral or tibial malunion, it can also result from metabolic bone disease (ie, Paget’s disease, rickets, osteomalacia), congenital deformity, prior osteotomy, or other deformities.
Surgeons often debate the best way to manage a patient with symptomatic knee arthritis and an extra-articular deformity. The 3 current options include a 2-stage procedure in which an extra-articular correctional osteotomy is performed several months before the primary TKR, a 1-stage procedure in which an extra-articular correctional osteotomy is performed at the time of the index TKR, or a 1-stage procedure in which TKR is performed with intra-articular bone resections and soft tissue releases to correct the extra-articular deformity.1 While each option has its appropriate indications, we prefer a 1-stage TKR with an intra-articular correction whenever possible.
First, assess the deformity radiographically using standing long-leg radiographs to completely measure the deformity in the femur and/or tibia. An extra-articular deformity generally produces deformities in the coronal, sagittal, and axial planes of rotation. Radiographic measurements should be correlated with the clinical examination, as the procedure requires a thorough understanding of both the bony and soft tissue deformities. Other factors to consider include age, weight, function, bone quality, underlying disease, additional deformities, previous incisions, infections, and the possible presence of retained hardware.
Next, proper planning involves cuts perpendicular to the mechanical axes of the femur and the tibia separately. The limitation of an intra-articular correction of an extra-articular deformity at the knee is the collateral ligament insertions. Planned bone resection should not compromise the collateral ligaments. As the ligamentous femoral insertions are approximately 25 mm from the joint line, it is not possible to resect >20 mm of bone from either condyle. If the lines drawn perpendicular to the mechanical axes encompass the insertions of the collateral ligaments, they may be adjusted up to 5° for 1 or both axes to avoid compromising these ligaments during resection. For all of these reasons, it is more difficult to correct an extra-articular deformity >20°.
In a varus deformity, a reduction osteotomy may also be necessary at the medial tibial plateau. The bone cuts, in addition to a significant degree of soft tissue releases including the posterior cruciate ligament, posterior capsule, medial superficial collateral ligament, and pes anserinus, should help obtain a balanced rectangular space in the joint.
Finally, after checking the rotational alignment in flexion, we recommend the use of a standard posterior stabilized knee or a constrained condylar knee for added stability.
This technique has been successfully used in 15 cases by the senior author (C.S.R.) between 1980 and 1998. Two patients with arthritis of the knee and a severe extra-articular deformity were treated with an intra-articular correction of the extra-articular deformity according to the described technique and were evaluated via routine clinical and radiographic examination and Knee Society pain and functional scores.
An 84-year-old man had a 33° varus deformity of the tibia with 20° recurvatum due to a malunited tibial fracture. Proper planning revealed the need for a 20-mm wedge resection based laterally, as well as the need for a reduction osteotomy of the medial tibial plateau (Figure 2). Soft tissue balancing included release of the posterior cruciate and deep collateral ligaments and controlled elongation of the medial superficial collateral ligament, resulting in an even and balanced knee.
A 75-year-old woman had a 32° valgus deformity due to an old malunited femoral fracture. Planning revealed the need for a medially based resection of 20 mm from the distal femur and proximal tibia (Figure 3). Soft tissue balancing included the release and elongation of the posterolateral capsule and iliotibial band, respectively, resulting in an even and balanced knee.
The procedure was clinically successful in both patients without complications. At 2-year follow-up, Knee Society Scores improved from 40 to 95, and there was no evidence of instability in either case (Figure 4).
It is important to note that correcting an extra-articular deformity intra-articularly with a 1-stage TKR is difficult and does not apply to all cases of arthritis with an extra-articular deformity. Angular deformities closer to the knee and >20° are more challenging but still possible. The determination depends on whether the planned bone cuts compromise the insertion of either collateral ligament with 20 mm trapezoidal wedge resection.
For femoral deformities, if the planned cuts perpendicular to the mechanical axis of the femur at the femoral condyle does not pass through the insertions of the collateral ligaments, intra-articular correction is possible. The procedure is indicated for tibial deformities if the anatomical axis of the tibia distal to the deformity does not cut through the insertions of the collateral ligaments (Figure 1). If the deformity is so large that the line compromises the ligaments, an extra-articular correctional osteotomy may be indicated.2,3
Both of our patients were at least 60 years old, had an extra-articular deformity <35° in the coronal plane, a flexion contracture <30°, good quadriceps status, and a range of motion (ROM) of >90° preoperatively. Most patients meeting these criteria should be eligible for our 1-stage procedure.
Our technique provides many benefits. A 1-stage procedure is cost effective, requiring less hospitalization and a shorter length of stay. Additionally, as evidenced by our experience and the experience of others, the procedure is reproducible and may even provide for better outcomes. Extra-articular osteotomy options can lead to malunion or nonunion, instability, decreased ROM, and other complications. As correctional osteotomy options also increase incision area, prolong rehabilitation, and increase the chance of infection, our preferred method is the 1-stage TKR intra-articular corrective technique.3-7
Other surgeons have addressed this debate in great detail. Lonner et al4 reported the effective management of extra-articular deformity with simultaneous extra-articular osteotomy but with some complications and technical difficulty. Although Wolff et al7 reported some cases of instability after intra-articular correction and TKR due to asymmetrical bone resection, we believe this can be compensated for with soft tissue balancing and a stabilized prosthesis. Ritter and Faris6 believed that with proper attention to ligamentous instability, any deformity could be intra-articularly corrected and found that outcomes following extra-articular osteotomy (staged or simultaneous) provided for worse alignment and poorer ROM. Additionally, Wang and Wang3 reported no complications due to TKR in 13 successful cases performing a similar technique of TKR in conjunction with intra-articular bone resection. Finally, Mann et al2 achieved satisfactory results in 15 patients from 1980-1997 with the outlined technique.
One-stage TKR with intra-articular correction of extra-articular deformity is a complex procedure. However, with proper planning, appropriate bone cuts to restore alignment, and the necessary soft tissue releases to balance the knee in flexion and extension, a satisfactory TKR can be achieved. The procedure is reproducible, cost effective, and patient preferred, and perhaps provides better outcomes, making it our treatment of choice.
- Archibeck MJ, White RE Jr. What’s new in adult reconstructive knee surgery. J Bone Joint Surg Am. 2003; 85(7): 1404-1411.
- Mann JW III, Insall JN, Scuderi GR. Total knee arthroplasty in patients with associated extra-articular angular deformity. Orthop Trans. 1997; (21):59.
- Wang JW, Wang CJ. Total knee arthroplasty for arthritis of the knee with extra-articular deformity. J Bone Joint Surg Am. 2002; 84(10):1769-1774.
- Lonner JH, Siliski JM, Lotke PA. Simultaneous femoral osteotomy and total knee arthroplasty for treatment of osteoarthritis associated with severe extra-articular deformity. J Bone Joint Surg Am. 2000; 82(3):342-348.
- Papagelopoulos PJ, Karachalios T, Themistocleous GS, Papadopoulos ECh, Savvidou OD, Rand JA. Total knee arthroplasty in patients with pre-existing fracture deformity. Orthopedics. 2007; 30(5):373-378.
- Ritter MA, Faris GW. Total knee replacement following extra-articular deformities. Orthopedics. 2003; 26(9):969-970.
- Wolff AM, Hungerford DS, Pepe CL. The effect of extraarticular varus and valgus deformity on total knee arthroplasty. Clin Orthop Relat Res. 1991; (271):35-51.
Mr Koenig and Drs Maheshwari, Ranawat (Amar), and Ranawat (Chitranjan) are from the Hospital for Special Surgery, New York, New York.
Mr Koenig and Drs Maheshwari, Ranawat (Amar), and Ranawat (Chitranjan) have no relevant financial relationships to disclose.
Presented at Current Concepts in Joint Replacement 2008 Winter Meeting; December 10-13, 2008; Orlando, Florida.
“Orthopaedic Crossfire” is a registered trademark of A. Seth Greenwald, DPhil(Oxon).
Correspondence should be addressed to: Chitranjan S. Ranawat, MD, Hospital for Special Surgery, 535 E 70 St, 6th Floor, New York, NY 10021.