Comparison of Sagittal and Frontal Plane
Alignment After Open- and Closed-wedge
Osteotomy: a Matched-pair Analysis
TK S
CHAEFER1, M M
AJEWSKI1,2, MT H
IRSCHMANN1ANDNF F
RIEDERICH11Department of Orthopaedic Surgery and Traumatology, Kantonsspital Bruderholz, Bruderholz, Switzerland;2Department of Orthopaedic Surgery and Traumatology, University
Hospital of Basel, Basel, Switzerland
High tibial osteotomy (HTO) is a procedure for treating medial compartment osteoarthritis (OA) of the varus deformed knee. Frontal and sagittal alignment after closed- and open-wedge HTO were compared radiologically in a matched-pair study. The mean intra-operative frontal plane correction (FT axis) was +7.5° for closed-wedge HTO and +8° for open-wedge HTO; it increased by +0.5° in closed-wedge HTO and decreased by –0.5° in open-wedge HTO at last follow-up.
Post-operatively, tibial slope had decreased by –0.5° in closed-wedge HTO and increased significantly by +3° in open-wedge HTO. Both techniques effectively and safely corrected varus deformity. A high degree of stability of the frontal plane correction was noted, however a significant change in the tibial slope after open-wedge HTO was observed post-operatively. As no loss of correction was shown, it may be related to the surgical technique rather than to the implant used.
Introduction
First described by Jackson and Waugh1 in 1961, high tibial osteotomy (HTO) is a well-established procedure for treating medial compartment osteoarthritis (OA) of the varus deformed knee. In HTO, the bone of the upper tibia is cut and repositioned. Either a wedge is opened up to improve the alignment (open-wedge HTO) or a wedge of bone is removed (closed-wedge HTO). Good subjective and objective mid-term results of up to 80 – 90% at 5-year follow-up have been reported for closed-wedge HTO.2 – 5 However, in light of the possible severe
adverse events and the technical demands of closed-wedge osteotomies, medial open-wedge HTO has become a popular technique.4,6 – 10 Several authors have reported that open-wedge HTO appears to cause minimal soft tissue scarring and less distortion of the proximal tibia, which is important for the correct implantation of the tibial component, should a secondary total knee arthroplasty become necessary.8,11 – 14 Conversely, open-wedge HTO can result in significant post-operative loss of correction compared with closed-wedge osteotomies.15 – 17 Angle stable implants with interlocking
screws promise better stability and less post-operative loss of correction.18 – 20
It is well known, however, that all techniques which correct frontal plane misalignment may also change sagittal plane alignment.17,21Posterior tibial slope is considered to be an important factor in knee joint kinematics.8,22 – 26 The current retrospective matched-pair analysis of patients treated for medial compartment osteoarthritis with open- or closed-wedge HTO analysed the frontal and sagittal femorotibial (FT) knee alignment and compared the different osteotomy options.
Patients and methods
PATIENTS
A review of archived medical records (including surgical reports and radiographs) was performed to identify all patients who underwent open- or closed-wedge HTO for the treatment of osteoarthritis of the medial compartment of the knee with a varus deformity in the Bruderholz Hospital, affiliated to the University of Basel, between 1996 and 2002.
For comparison of the closed-wedge HTO, described by Müller et al.16(Figs 1 and 2), and the open wedge HTO using the Puddu plate (Arthrex, Naples, FL, USA) (Fig. 3), subjects were matched with respect to gender, age, weight, height and body mass index (BMI).
RADIOLOGICAL EVALUATION
Standardized radiographs for each patient were analysed by one independent observer who had not been involved in the surgical procedure. The radiographs had been obtained under fluoroscopy in the radiology department of that institution, using the same technical equipment and team, pre-and immediately post-operatively, pre-and at 4 and 8 weeks’ and at 6 months’ follow-up. A 35 × 43 cm cassette was used. The
radiographs were anteroposterior full weight-bearing (in a one-leg standing position) and lateral with the patient prone and the knee flexed to 30°, which was controlled by goniometer.
The following angles and axes were measured. (i) The FT axis, defined as the angle between the anatomical axis of the femur and the tibia. The anatomical axis of the femur was defined as a line through the middle of the shaft at the junction of the middle and distal thirds to the centre of the knee joint. Values for valgus were defined as
FIGURE 1: Closed wedge high
positive (+) and values for varus as negative (–). The centre of the knee joint was defined at the height of the joint line in the middle of the edges of the tibial plateau. The achieved intra-operative correction was calculated as the difference between the pre- and post-operative follow-up values for the FT axis. (ii) The width of the medial and lateral joint lines, measured by calculating the interbone distance between the outer edge of the tibia plateau and the outer turning point of the femoral condylus using a magnifying glass. (iii) The tibial slope (tibial inclination), using the method of Oswald et al.27 (Fig. 4). Different methods have been used previously to measure the tibial slope in lateral X-rays.17,21,27 Since the normal anatomical tibial slope is in a posterior and downward
direction, posterior tibial slope values were defined as positive (+) and anterior slope values were defined as negative (–).
STATISTICAL ANALYSIS
Unless otherwise stated, data are presented as mean ± SD. To analyse the differences between pre-operative, post-operative and last follow-up measurements for the two groups, t-tests for paired samples and for independent samples were performed. Goodness of fit with the normal distribution was proven with the Kolmogorov–Smirnov test. P-values ≤ 0.05 were considered to be statistically significant. The statistical package SPSS® version 11.5 (SPSS Inc., Chicago, IL, USA) for Windows was used for all statistical analyses.
FIGURE 2: Anteroposterior and lateral radiographs after closed-wedge high tibial
Results
PATIENTS
The review of medical records identified 156 patients who underwent HTO (90 open- and 66 closed-wedge) for the treatment of osteoarthritis of the medial compartment of the knee with a varus deformity. Fifty-eight patients met the matching criteria, giving 29 matched pairs (nine pairs of men and 20 pairs of women). The open- and closed-wedge HTO groups did not differ significantly in age, weight, height or BMI. At index surgery, the closed-wedge HTO group had a mean age of 47 years (range 26 – 65 years), a mean weight of 82 kg (range 65 – 106 kg), a mean height of 176 cm (range 155 – 190 cm) and a mean BMI of 26.7 kg/m2(range 19.8 – 32.9 kg/m2). In the open-wedge HTO group the mean age was 46 years (range 26 – 64 years), the mean
weight 81 kg (range 50 – 114 kg), the mean height 174 cm (range 152 – 200 cm) and the mean BMI 26.5 kg/m2 (range 18.6 – 32.8 kg/m2). Mean follow-up time was 11 months (range 6 – 24 months) in both groups.
In all cases the index surgery was carried out by experienced consultants and the post-operative regimen was identical for both treatment groups. Full weight bearing was initiated at 8 weeks post-operatively. Clinical and radiological follow-ups were conducted 4 and 8 weeks after index surgery. An additional clinical and radiological evaluation was done 6 months post-operatively to evaluate bone healing, frontal plane correction and, if evident, change in the sagittal plane alignment.
FT AXIS MEASUREMENTS
The pre-operative FT axis values in the
FIGURE 3: Anteroposterior and lateral radiographs after open-wedge high tibial
closed- and open-wedge HTO groups did not differ (–0.5° ± 2.5°). In the closed-wedge HTO group, the mean ± SD intra-operative correction of the FT axis was +7.5° ± 2.0° and, in the open wedge HTO group, it was +8.0° ± 3.0°. The post-operative FT axis was +7.0° ± 2.0° in the closed-wedge HTO group and +7.5° ± 3.0° in the open-wedge HTO group. At last follow-up, the mean ± SD FT axis was +7.5° ± 2.5° in the closed-wedge HTO group and 7.0 ± 2.5° in the open wedge group. No significant differences were evident (Table 1).
WIDTH OF MEDIAL AND LATERAL
JOINT LINES
The pre-operative values for the mean ± SD width of the joint lines in the medial and lateral compartments were 4 ± 2 mm/8 ± 2 mm in the closed-wedge HTO group and 3 ± 2 mm/6 ± 2 mm in the open-wedge HTO group. At last follow-up, the widths were 4 ± 1 mm/8 ± 2 mm and 4 ± 1 mm/6 ± 2 mm in the closed- and open-wedge HTO groups, respectively. There were no significant differences in the pre-operative values within or between any of the groups.
TIBIAL SLOPE (TIBIAL
INCLINATION)
Pre-operative values for tibial slope were 7.5° ± 3.0° in the closed-wedge HTO group and 9.0° ± 4.0° in the open-wedge HTO group. The mean ± SD tibial slope post-operatively in the closed wedge HTO group was 7.0° ± 3.0° giving a change of –0.5° (not statistically significant). The mean ± SD tibial slope in the open wedge HTO group post-operatively was 12.0° ± 5.0° giving a significant change of +3.0° ± 5.0° versus the pre-operative values (P = 0.017). These values were similar at the last follow-up examination and showed a significant difference in the sagittal alignment between the closed- and open-wedge groups (P = 0.000) (Table 1, Fig. 5). The open-wedge technique seemed to affect the tibial slope directly and significantly after the operation.
ADVERSE EVENTS
Post-operatively there were two cases of early soft tissue infection in the closed-wedge HTO group compared with one case in the open-wedge HTO group. Deep venous thrombosis occurred in two cases in the open-wedge HTO group compared with none in the closed-wedge HTO group. At last follow-up, subjective evaluation by the patients on a
FIGURE 4: Measurement of tibial
slope in lateral X-rays, as described by Oswald et al.27The tangent to the medial tibial plateau is considered to be the proximal reference line (A). This is the line connecting the highest anterior and posterior points of the medial plateau. The second reference is the axis of the tibia, defined as a line through the middle of the shaft at 10 and 20 cm (B).27 The angle between these two lines is the tibial slope (C)
A C
B 10
FIGURE 5: Box and whisker diagram of the changes in tibial slope observed in
closed-wedge versus open-closed-wedge high tibial osteotomy. Radiographs associated with 58 patients treated for media compartment osteoarthritis of the varus deformed knee were assessed (*P = 0.017 for post- versus pre-operative for open-wedge HTO;†P = 0.000 for post-operative open- versus closed-wedge HTO)
Method 0° 5° 10° 15° 20° 25°
Open-wedge HTO Closed-wedge HTO Mean values * † T ib ia l sl o p e Pre-operative Post-operative Last follow-up
Change of FT axis and tibial slope (º) Closed-wedge HTO Open-wedge HTO Mean Median Mean Median
FT axis
Pre-operative –0.5 ± 2.5 0 –0.5 ± 2.5 0
Achieved intra-operative correction +7.5 ± 2.0 +8.0 ± 3.0
Post-operative +7.0 ± 2.0 +8 +7.5 ± 3.0 +8 Last follow-up +7.5 ± 2.5 +9 +7.0 ± 2.5 +7 Tibial slope Pre-operative +7.5 ± 3.0 +8 +9.0 ± 4.0 +9 Post-operative +7.0 ± 3.0 +7 +12.0 ± 5.0*† +11 Change of slope –0.5 ± 2.0 0 +3.0 ± 5.0*† +4 Last follow-up +7.0 ± 3.0 +7 +12.0 ± 5.0 +11
*P = 0.017 for post- versus pre-operative for open-wedge HTO.
†P = 0.000 for post-operative open- versus closed-wedge HTO.
TABLE 1:
Likert-type scale (0 – 3) showed 12 very satisfied, 15 satisfied, two disappointed and no dissatisfied patients in the closed-wedge HTO group compared with eight very satisfied, 19 satisfied, two disappointed and no dissatisfied patients in the open-wedge HTO group. Overall there was no significant difference in adverse events between the two groups.
Discussion
Lower limb alignment is of paramount importance for static and dynamic joint load. Varus angulation can lead to medial overload with cartilage deterioration and early degenerative changes.23,28 Patients with OA of the medial compartment with a varus deformity can be successfully treated using HTO.1 – 6,10,11 Many different surgical techniques as well as implants have been used, each with inherent advantages and disadvantages. Closed-wedge osteotomies have been used for a long time with satisfying results,1 – 5 however potential complications include peroneal nerve or popliteal artery lesions, deep vein thrombosis and lung embolism as well as non-union or intra-articular fractures.3
Open-wedge techniques have been introduced to try to overcome these complications and are now commonly used by many orthopaedic surgeons.9,10There are, however, some concerns about reported complications with these techniques. For example, Spahn15 described a complication rate of 43.6% after open-wedge HTO and Warden et al.29found delayed union in 6.6% of cases and non-union in 1.6% of cases following 182 open-wedge HTO procedures. Additionally, Staubli et al.19 described hyposensitivity in the area of the infrapatellar branch of the saphenous nerve in 10 out of 92 patients.
A loss of correction in the frontal plane is
possibly one of the most common problems identified at follow-up in both open- and closed-wedge HTO.3,9 Magyar et al.9 described a 2 – 3º loss after 2 years in open wedge osteotomies and, therefore, recommended a slight over-correction intra-operatively to improve the long-term results. In this study, there were only slight changes in the frontal plane alignment at the last follow-up, with an over-correction in closed-wedge HTO and a loss of correction in open-wedge HTO of < 1°. This finding implicates that the stability of the osteotomy was not a problem in either group.
In addition to changes of the frontal plane, Çullu et al.17 described a significant change in the sagittal alignment after focal dome osteotomy. In another study, Marti et
al.21 described a tendency to an increase in posterior tibial slope after open-wedge HTO. A significant increase in the posterior slope in the open-wedge HTO group directly after surgery was seen in the current study and this supports the conclusion that the open-wedge technique is inherently prone to increases in the tibial slope.
posterior tibial cartilage erosion than those with a normal tibial slope.4,31 The importance of the tibial slope is also shown in the studies of Slocum and colleagues,24 – 26 who treated ACL lesions in canines with a slope-changing osteotomy to regain stability without ACL reconstruction.
In the present study, neither significant frontal nor sagittal plane changes were seen in the closed-wedge HTO group. Immediate stability of the osteotomy seems to be an advantage of the HTO technique of Müller et
al.,16and they identified a remaining bridge of 1.5 cm on the medial side and direct cortex to cortex contact on the lateral side (without any step at the level of the osteotomy) as key factors. Immediate stability has also been achieved by using implants with angular stability for open-wedge HTO.18 – 20
Widening of the joint space was also assessed in the present study: this parameter may indirectly reflect reduced stress to the
medial compartment. As expected, the medial joint space was wider in both groups after osteotomy. There was no significant between-group difference.
In conclusion, the two techniques of HTO (closed- and open-wedge) used in this matched-pair study proved to be effective and safe methods to correct varus deformity. Over time, a high level of stability in the frontal plane correction was observed in both methods. In contrast, there was significant change in the posterior tibial slope (sagittal alignment) directly post-operative after open-wedge HTO. This difference may be particularly important in ACL-deficient knees. As no significant loss of correction was shown, this finding is more probably related to the surgical technique than to the implant itself.
Conflicts of interest
The authors had no conflicts of interest to declare in relation to this article.
• Received for publication 20 April 2008 • Accepted subject to revision 25 April 2008 • Revised accepted 8 August 2008
Copyright © 2008 Field House Publishing LLP
References
1 Jackson JP, Waugh W: Tibial osteotomy for osteoarthritis of the knee. J Bone Joint Surg Br 1961; 43B: 746 – 751.
2 Insall JN, Joseph DM, Msika C: High tibial osteotomy for varus gonarthrosis. A long-term follow-up study. J Bone Joint Surg Am 1984; 66: 1040 – 1048.
3 Flamme CH, Ruhmann O, Schmolke S, et al: Long-term outcome following high tibial osteotomy with tension bend principle. Arch Orthop Trauma Surg 2003; 123: 12 – 16. 4 Hernigou P, Medevielle D, Debeyre J, et al:
Proximal tibial osteotomy for osteoarthritis with varus deformity. A ten to thirteen-year follow-up study. J Bone Joint Surg Am 1987; 69: 332 – 354.
5 Yasuda K, Majima T, Tsuchida T, et al: A ten- to 15-year follow-up observation of high tibial osteotomy in medial compartment osteoarthrosis. Clin Orthop 1992; 282: 186 – 195. 6 Koshino T, Morii T, Wada J, et al: High tibial osteotomy with fixation by a blade plate for
medial compartment osteoarthritis of the knee. Orthop Clin North Am 1989; 20: 227 – 243. 7 Matthews LS, Goldstein SA, Malvitz TA, et al:
Proximal tibial osteotomy. Factors that influence the duration of satisfactory function. Clin Orthop 1988; 229: 193 – 200.
8 Fowler JL, Gie GA, Maceachern AG: Upper tibial valgus osteotomy using a dynamic external fixator. J Bone Joint Surg Br 1991; 73: 690 – 691.
9 Magyar G, Toksvig-Larsen S, Lindstrand A: Open wedge tibial osteotomy by callus distraction in gonarthrosis. Operative technique and early results in 36 patients. Acta Orthop Scand 1998; 69: 147 – 151.
10 Koshino T, Murase T, Saito T: Medial opening-wedge high tibial osteotomy with use of porous hydroxyapatite to treat medial compartment osteoarthritis of the knee. J Bone Joint Surg Am 2003; 85A: 78 – 85.
27: 435 – 440.
12 Katz MM, Hungerford DS, Krackow KA, et al: Results of total knee arthroplasty after failed proximal tibial osteotomy for osteoarthritis. J Bone Joint Surg Am 1987; 69: 225 – 233. 13 Windsor RE, Insall JN, Vince KG: Technical
considerations of total knee arthroplasty after proximal tibial osteotomy. J Bone Joint Surg Am 1988; 70: 547 – 555.
14 Mont MA, Alexander N, Krackow KA, et al: Total knee arthroplasty after failed high tibial osteotomy. Orthop Clin North Am 1994; 25: 515 – 525.
15 Spahn G: Complications in high tibial (medial opening wedge) osteotomy. Arch Orthop Trauma Surg 2003; 30: 1 – 6.
16 Müller W, Kentsch A, Schäfer N: The elastic high tibia valgus osteotomy in the varus deformity. Oper Tech Sports Med 2000; 8: 19 – 26. 17 Çullu E, Aydog˘du S, Alparslan B, et al: Tibial slope changes following dome-type high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 2005; 13: 38 – 43.
18 Lobenhoffer P, Agneskirchner J, Zoch W: Open valgus alignment osteotomy of the proximal tibia with fixation by medial plate fixator. Orthopade 2004; 33: 153 – 160 [in German]. 19 Staubli AE, De Simoni C, Babst R, et al: A new
LCP-concept for open wedge osteotomy of the medial proximal tibia – early results in 92 cases. Injury 2003; 34(suppl 2): B55 – B62. 20 Horácek D, Cech O, Weissinger M: Medial
opening-wedge high tibial valgus osteotomy, using a stable TomoFix plate, in genu varum arthritis: surgical technique. Acta Chir Orthop Traumatol Cech 2006; 73: 197 – 204 [in Czech]. 21 Marti CB, Gautier E, Wachtl SW, et al: Accuracy
of frontal and sagittal plane correction in open-wedge high tibial osteotomy. Arthroscopy 2004;
20: 366 – 372.
22 Giffin JR, Vogrin TM, Zantop T, et al: Effects of increasing tibial slope on the biomechanics of the knee. Am J Sports Med 2004; 32: 376 – 382.
23 Agneskirchner JD, Hurschler C, Stukenborg-Colsman C, et al: Effect of high tibial flexion osteotomy on cartilage pressure and joint kinematics: a biomechanical study in human cadaveric knees. Arch Orthop Trauma Surg 2004;
124: 575 – 584.
24 Slocum B, Devine T: Cranial tibial thrust: a primary force in the canine stifle. J Am Vet Med Assoc 1983; 183: 456 – 459.
25 Slocum B, Devine T: Cranial tibial wedge osteotomy: a technique for eliminating cranial tibial thrust in cranial cruciate ligament repair. J Am Vet Med Assoc 1984; 184: 564 – 569. 26 Slocum B, Slocum TD: Tibial plateau leveling
osteotomy for repair of cranial cruciate ligament rupture in the canine. Vet Clin North Am Small Anim Pract 1993; 23: 777 – 795. 27 Oswald MH, Jakob RP, Schneider E, et al:
Radiological analysis of normal axial alignment of femur and tibia in view of total knee arthroplasty. J Arthroplasty 1993; 8: 419 – 426.
28 Fujisawa Y, Masuhara K, Shiomi S: The effect of high tibial osteotomy on osteoarthritis of the knee. An arthroscopic study of 54 knee joints. Orthop Clin North Am 1979; 10: 585 – 608. 29 Warden SJ, Morris HG, Crossley KM, et al:
Delayed- and non-union following opening wedge high tibial osteotomy: surgeons’ results from 182 completed cases. Knee Surg Sports Traumatol Arthrosc 2005; 13: 34 – 37.
30 Dejour H, Neyret P, Bonnin M: Monopodal weight-bearing radiography of the chronically unstable knee. In: The Knee and Cruciate Ligaments (Jakob RP, Stäubli H-U, eds). Berlin: Springer, 1992; pp 568 – 576.
31 Goutallier D, Hernigou P, Medevielle D, et al: Outcome at more than 10 years of 93 tibial osteotomies for internal arthritis in genu varum (or the predominant influence of the frontal angular correction). Rev Chir Orthop Reparatrice Appar Mot 1986; 72: 101 – 113 [in French].
Author’s address for correspondence:
Thomas Schaefer MD
Department of Orthopaedic Surgery and Traumatology, Kantonsspital Bruderholz, CH-4101 Bruderholz, Switzerland.
