Original Article Correction of Proximal Tibia Varus with External Fixation Kashif Ashfaq, M.D. 1 Austin T. Fragomen, M.D. 1 Joseph T. Nguyen, M.P.H. 2 S. Robert Rozbruch, M.D. 1 1 Limb Lengthening and Complex Reconstruction Service (LLCRS), Address for correspondence and reprint requests S. Robert Rozbruch, Hospital for Special Surgery, New York, New York M.D., Associate Professor of Clinical Orthopaedic Surgery, Weill 2 Department of Biostatistics, Hospital for Special Surgery, New York, Cornell Medical College, 535 East 70th Street, New York, NY 10021 New York (e-mail: [email protected]). J Knee Surg Abstract Correction of proximal tibia varus deformity has been used with success. Our Protocol is to use monolateral frame to correct varus of less than 10 degrees and to use the Taylor spatial frame for deformities greater than 10 degrees and for multiplanar deformities. Is this protocol successful? Ninety-one limbs in 68 patients with proximal tibia varus were treated with percutaneous proximal tibial osteotomy and external fixation. The mono- lateral and spatial frames were used for 36 and 55 limbs, respectively. Each group was further subdivided into neutral or intentionally overcorrected subgroups. Monolateral group time of correction and time in frame was 15 days (8 to 20) and 101 days (81 to 133), respectively. The preoperative mechanical axis deviation (MAD) was 22 mm medial (10 to 44). Postoperative MAD in the neutral subgroup was 5 mm lateral (2 to 10) and 3 mm medial (0 to 7). Postoperative MAD in the overcorrected subgroup was 10 mm lateral (4 to 20) and one patient was 5 mm medial. Medial proximal tibial angle (MPTA) improved from 85 degrees (79 to 89) to 90 degrees (85 to 96) in the neutral group and to 92 degrees (85 to 98) in the overcorrected group. Spatial frame group time of correction and time in frame was 34 days (7 to 99) and 130 days (95 to 177), respectively. The preoperative MAD was 40 mm medial (range 5 to 155). This improved to 5 mm medial (0 to 30) and 4 mm lateral (0 to 7) in the neutral group, and 17 mm medial (0 to 35) and 11 mm lateral (4 to 28) in the overcorrection group. MPTA improved from 80 degrees (40 to 87) to 88 degrees (83 to 96) in the neutral group and Keywords to 84 degrees (89 to 97) in the overcorrected group. In both groups, there was no ► tibia vara significant change in the ankle or knee range of motion. There was one refracture in both ► proximal tibial groups. Our algorithm for treating proximal tibial varus deformities is safe and effective. Downloaded by: New EnglandBaptist Hospital. Copyrighted material. osteotomy For simple varus deformities, we recommend use of the monolateral frame. We reserve ► external fixation the use of the spatial frame for large or complex deformity correction. Malalignment of the mechanical axis of the lower extremity the treatment of OA of the knee. PTO has gained acceptance as and rotational deformity can lead to the transmission of a treatment option for young patients with lower extremity – abnormal forces across the knee joint.1 3 This may later bring varus malalignment and symptomatic medial tibiofemoral – about osteoarthritis (OA)2,4 6 affecting the patients quality of compartment arthrosis. The value of osteotomy to correct life by causing pain, further deformity, and limiting daily malalignment has followed the principle of transferring load routine activities.7,8 Proximal tibial osteotomy (PTO) was first to the unaffected (lateral) compartment of the knee to relieve reported by Jackson et al9 in 1958 as a surgical procedure for symptoms and slow disease progression on the medial side. received Copyright © 2012 by Thieme Medical DOI http://dx.doi.org/ April 27, 2011 Publishers, Inc., 333 Seventh Avenue, 10.1055/s-0031-1299659. accepted after revision New York, NY 10001, USA. ISSN 1538-8506. October 5, 2011 Tel: +1(212) 584-4662. Correction of Proximal Tibia Varus with External Fixation Ashfaq et al. As Coventry1,10 advocated, the results of high tibial osteot- tibial osteotomy surgery for deformity correction using either omy (HTO) in this scenario have been best when the anatom- the monolateral or the spatial frames using our protocol ical axis is corrected to 8 to 10 of valgus.11 However, too much between 2000 and 2007. Our indication for use of mono- overcorrection may yield poor results, particularly in liga- lateral fixator was varus deformity in the proximal tibia of mentously lax individuals, in which bony overcorrection may less than 10 degrees and for the spatial frame, varus deformity lead to a significant clinical deformity. Closing wedge osteot- of greater than 10 degrees, oblique plane deformity, presence omy by an open technique has several limitations including of rotational deformity, or compromised soft tissue. In the wide exposure, lack of accuracy, loss of bone stock, proximal spatial frame group, the average age was 39 years (range 21 to migration of fibula, and can lead to nerve compromise, 72 years), and in the monolateral group, the average age was wound problems, and compartment syndrome as the defor- 44 years (range, 23 to 73 years). Twenty-three of the 68 – mity is corrected acutely.12 15 Percutaneous PTO performed patients had bilateral surgeries. Thirteen patients had spatial distal to the tibial tubercle is a technique that has been used to frames on both legs, while seven patients had monolateral correct varus deformities.1,7,16 It does not adversely affect frames on both legs. Three patients were treated with both metaphyseal bone stock and does not affect the patellar spatial and monolateral frames (one on each leg). In the tendon tension. spatial frame group, deformity was corrected in 34 days (17 For varus deformity of less than 10 degrees, we use the to 99), whereas total time in the frame averaged 130 days (95 monolateral frame for gradual correction. The fibula is not cut to 177). In the monolateral group, deformity was corrected in and lateral cortex of the tibia is left intact. For varus deformity 15 days (8 to 20), whereas total time in the frame averaged of greater than 10 degrees or if associated with sagittal or 101 days (81 to 133). The average preoperative varus defor- axial plane deformity, we use Taylor spatial frame (TSF; Smith mity in the monolateral group was 7 degrees (4 to 9), while in and Nephew Inc., Memphis, TN) for gradual correction. The the spatial frame group, it was 12 degrees (4–46) (►Table 4). fibula is cut and a PTO is performed. With the use of this The cause of deformity included traumatic, congenital, devel- protocol, we have addressed all proximal tibial deformity on opmental, and neurologic etiologies. our service. Patients were subdivided into two groups depending on In our experience, gradually correcting the proximal tibial the presence or absence of unicompartmental knee arthri- varus deformities of less than 10 degrees by using the hemi- tis11,22 and the goal of correction. Group 1 included patients callotasis monolateral frame and 10 degrees of varus defor- without medial joint space narrowing. The goal of realign- mity or greater with or without sagittal and/or axial plane ment in this group was MAD of 0 mm. Group 2 included deformity by using spatial frame avoids the common prob- patients with medial joint space narrowing and the goal was lems associated with the closing wedge HTO via techniques overcorrection to 10 mm lateral. such as Puddu plate. There were 13 extremities out of 36 in the monolateral The procedure involves small incisions and minimal soft group, and 28 extremities out of 55 in the spatial frame group tissue stripping. The spatial frame corrects angulation and which were intentionally overcorrected to unload medial com- translation in the coronal, sagittal, and axial planes around a partment OA. The average follow-up after surgery was 51 (14 to virtual hinge, hence the term “six-axis correction.” The stability 85) months in the monolateral group and 74 (13 to 127) months of this multiplanar circular fixator permits early weight bearing in the spatial frame group. Four patients in the monolateral and and provides an ideal environment for both new-bone formation five in the spatial frame group were lost to follow-up. and soft tissue healing. Computer-generated schedules and We arranged the postoperative MAD to either medial or struts have greatly simplified patient involvement, which is lateral separately. This was done to illustrate most accurately Downloaded by: New EnglandBaptist Hospital. Copyrighted material. crucial to the success of this technique. Studies have re- the final alignment. We also averaged the postoperative MAD – ported17 21 few complications with the use of spatial frame. as an absolute deviation from the goal of treatment. This is a We asked the following questions regarding the accuracy more useful way to apply statistics to the data. of both the spatial and the monolateral frames in correcting Clinical preoperative evaluation included history and the proximal tibial varus deformity: physical examination. Gait was observed. Frontal plane de- formity was measured on a 51-inch erect leg, bipedal radio- 1. How accurate is the mechanical axis deviation (MAD) graph. MAD and MPTA were measured using the methods correction at the proximal tibia? described by Paley.3 For tibia vara with a normal femur, the 2. How accurate is the medial proximal tibial angle (MPTA) proximal mechanical axis of the tibia was established by correction at the proximal tibia? extending a line drawn from the center of hip through the 3. What are the outcomes regarding Short Form-36 (SF-36) center of knee. When neutral mechanical axis alignment was scores, rate of complications, and need for knee replacement? the goal, the proximal mechanical axis line was drawn 4.