- Email: [email protected]
Effect of Combined Fibular Osteotomy on the Pressure of the Tibiotalar and Talofibular Joints in Supramalleolar Osteotomy of the Ankle: A Cadaveric Study
The Journal of Foot & Ankle Surgery 56 (2017) 59–64
Contents lists available at ScienceDirect
The Journal of Foot & Ankle Surgery journal homepage: www.jfas.org
Effect of Combined Fibular Osteotomy on the Pressure of the Tibiotalar and Talofibular Joints in Supramalleolar Osteotomy of the Ankle: A Cadaveric Study Gi Won Choi, MD, PhD 1, Soon Hyuck Lee, MD, PhD 2, Kyung Wook Nha, MD, PhD 3, Sung Jae Lee, PhD 4, Won Hyeon Kim, BE 4, Chang-Sub Uhm, MD, PhD 5 1
Department Department Department 4 Department 5 Department 2 3
of of of of of
Orthopaedic Surgery, Korea University Ansan Hospital, Ansan-si, Gyeonggi-do, South Korea Orthopedic Surgery, Korea University Anam Hospital, Seoul, South Korea Orthopedic Surgery, Inje University Ilsanpaik Hospital, Goyang-si, Gyeonggi-do, South Korea Biomedical Engineering, Inje University, Gimhae-si, Gyeongsangnam-do, South Korea Anatomy, College of Medicine, Korea University, Seoul, South Korea
a r t i c l e i n f o
a b s t r a c t
Level of Clinical Evidence: 5
We investigated the effect of combined fibular osteotomy on the pressure of the tibiotalar and talofibular joints in medial opening-wedge supramalleolar osteotomy. Three different tibial osteotomy gaps (6, 8, and 10 mm) were created in 10 cadaveric models, and the pressure in the tibiotalar and talofibular joints was measured under axial load before and after fibular osteotomy. The heel alignment angle and talar translation ratio were evaluated radiographically. An increase in osteotomy gap led to increases in hindfoot valgus (p ¼ .001) and the contact and peak pressures in the talofibular joint (p ¼ .03 and p ¼ .004). In contrast, the contact and peak pressures in the tibiotalar joint were unchanged with an increasing osteotomy gap (p ¼ .52 and p ¼ .76). Fibular osteotomy reduced the contact and peak pressures in the talofibular joint (p < .001 and p ¼ .001, respectively), and it did not influence the contact and peak pressures in the tibiotalar joint (p ¼ .46 and p ¼ .14, respectively). Therefore, fibular osteotomy might be necessary in supramalleolar osteotomy for medial ankle arthritis to minimize the increase in pressure in the talofibular joint, especially when the osteotomy gap is large. Ó 2016 by the American College of Foot and Ankle Surgeons. All rights reserved.
Keywords: ankle joint joint contact pressure pressure sensor supramalleolar osteotomy
Supramalleolar osteotomy has been used to treat asymmetric ankle osteoarthritis with a partially preserved tibiotalar joint surface (1,2). Medial opening-wedge supramalleolar osteotomy to treat medial ankle arthritis restores joint orientation and causes a load shift to a portion of the joint that is not involved in the degenerative process, thus, improving ankle function and relieving pain (3–8). Several clinical studies have reported good results of medial opening-wedge supramalleolar osteotomy with fibular osteotomy for medial ankle arthritis (9,10), but other studies have reported good results with medial opening-wedge supramalleolar osteotomy without fibular osteotomy (11,12). Furthermore, Lee and Cho (13) suggested that their new oblique supramalleolar opening-wedge osteotomy without fibular osteotomy minimizes the adverse effects Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Soon Hyuck Lee, MD, PhD, Department of Orthopaedic Surgery, Korea University Anam Hospital, 73, Inchon-ro, Seongbuk-gu, Seoul 02841, South Korea. E-mail address: [email protected] (S.H. Lee).
of mortise distortion and enhances osteotomy site stability by the presence of an intact fibula. A combined fibular osteotomy in medial opening-wedge supramalleolar osteotomy might affect the biomechanics of the tibiotalar and talofibular joints. Angular or rotational deformity of the distal fibula plays an important role in determining the contact areas and pressure distribution at the tibiotalar joint. Also, the effect of the fibula on the biomechanics of the tibiotalar joint is more marked with valgus deformity than with varus (6). The load can be transmitted by way of the talofibular joint, and the fibula can take part in the load transfer, particularly in valgus deformities (5). Lateral subfibular pain can develop after medial opening-wedge supramalleolar osteotomy because of valgus angulation and lateral translation of the hindfoot (9). Although combined fibular osteotomy in medial opening-wedge supramalleolar osteotomy can biomechanically affect the tibiotalar and talofibular joints, the indication of fibular osteotomy has not been clearly established. Furthermore, few data have been reported regarding the biomechanical effects of combined fibular osteotomy.
1067-2516/$ - see front matter Ó 2016 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2016.08.003
60
G.W. Choi et al. / The Journal of Foot & Ankle Surgery 56 (2017) 59–64
The purpose of the present study was to investigate the effect of combined fibular osteotomy on the pressure of the tibiotalar and talofibular joints in a cadaveric medial opening-wedge supramalleolar osteotomy model. We hypothesized that the talofibular joint pressure would increase after medial opening-wedge supramalleolar osteotomy without fibular osteotomy and that combined fibular osteotomy would reduce the increase in talofibular joint pressure. Materials and Methods
Specimen Preparation and Testing Setup Ten fresh-frozen, above-the-knee amputation specimens were obtained from 4 male donors and 1 female donor, with a mean age of 72 (range 56 to 85) years. Bony malalignment was excluded radiologically, and a normal range of motion in the ankle joint was verified in all specimens. Before the experiment, all the specimens were thawed at room temperature for 24 hours. The knee joints were disarticulated, preserving the intact tibiofibular joint. The skin, subcutaneous tissue, and muscles of the proximal tibiofibular joint and ankle joint were removed with preservation of the interosseous membranes and ligaments. The tibial plateau was transected, and the customized plate with a stem was inserted into the tibia after reaming the intramedullary canal. Additionally, two 6.5-mm Asnis III cannulated screws (Stryker, Mahwah, NJ) were inserted through the 2 holes on both sides of the stem. The specimen fixed to the plate was attached to a loading machine (FMS-2500-L2P force measurement system; LS Starrett Co., Athol, MA) using a ball-socket jig, which allows free axial rotation and angulation of the tibia under axial load (Fig. 1). The point of the load axis on the foot plate was marked as the point of intersection of vertical and horizontal lines. To match the talar dome center to the load axis, the talar dome center was positioned to coincide with both vertical and horizontal lines on the foot plate. The heel was buttressed by a lateral block to prevent the heel from sliding laterally, and the forefoot was stabilized with a strap. The K-Scan 4000 system (Tekscan, South Boston, MA) was used to measure the pressure and force in the tibiotalar and talofibular joints. It consists of scanning electronics, software, and flexible thin-film (0.10-mm) sensors. The sensor has 2 identical, independent sensing arrays. Each sensing array is composed of printed circuits with grids of load-sensing regions. A “sensel” refers to each load-sensing region within the
grid. Each sensing array has a total 920.7-mm2 matrix area (27.9 mm 33.0 mm), 572 sensels, and a density of 62.0 sensels/cm2. Anterior and posterior ankle arthrotomies were performed to insert 1 sensor into the tibiotalar joint. The anterior and posterior talofibular ligaments were divided to insert the other sensor into the talofibular joint, and they were repaired with nylon 3-0 sutures after inserting the sensor. To avoid the sensors breaking away from the joints, the edges of the sensors were sutured to the surrounding periosteum and capsular tissues of the 2 joints anteriorly and posteriorly with Vicryl 2-0 suture. A maximal load of 700 N was applied to simulate a single-leg stance with mean body weight (13). After 15 preconditioning cycles with a 700-N load, the static axial load was increased continuously from a 50 N preload to 700 N. The maximum load was maintained for 2 seconds, and peak pressures were captured at 50 Hz. The pressure magnitude and distribution, contact area, and force transmitted were measured using K-Scan 4000 software (Tekscan).
Osteotomy Procedures For the medial opening-wedge supramalleolar osteotomy, the osteotomy plane was initiated 4 to 5 cm proximal to the tip of the medial malleolus and directed obliquely toward the syndesmosis, preserving the lateral cortex of the tibia (9,11,13). To create 3 different heights of the osteotomy gap, the osteotomy was stabilized using the H-plate (Arthrex, Naples, FL), which has 3 different block heights (6, 8, and 10 mm) after medial opening of the osteotomy. To prevent displacement of the osteotomy gap during the experimental axial load, a unilateral external fixator was also applied to the medial aspect of distal tibia. After measuring the joint contact pressures under 3 different tibial osteotomy conditions (6-, 8-, and 10-mm osteotomy gaps), a fibular osteotomy was performed in an inferomedial direction at the same level as that of the tibial osteotomy (9,14). After bending a one-third tubular plate to fit the valgus angulation of the fibular osteotomy site, which was determined by the height of the osteotomy gap, the plate was fixed with screws. Therefore, 7 different conditions were created in each specimen according to the combined fibular osteotomy and tibial osteotomy gap size as follows: 1. 2. 3. 4. 5. 6. 7.
Intact specimen (before osteotomy) Tibial osteotomy gap of 6 mm Tibial osteotomy gap of 8 mm Tibial osteotomy gap of 10 mm Tibial osteotomy gap of 6 mm with fibular osteotomy Tibial osteotomy gap of 8 mm with fibular osteotomy Tibial osteotomy gap of 10 mm with fibular osteotomy
Fig. 1. Experimental setup. The specimen was fixed with the customized plate attached to the loading machine. Two identical, independent Tekscan pressure sensors were placed in the tibiotalar and talofibular joints, respectively.
G.W. Choi et al. / The Journal of Foot & Ankle Surgery 56 (2017) 59–64
Fig. 2. Changes in contact area, force transmission, contact pressure, and peak pressure in the tibiotalar joint with increasing tibial osteotomy gap in groups A and B (N ¼ 10 cadavers). Mean values and 95% confidence intervals (whiskers) are shown.
61
Fig. 3. Changes in contact area, force transmission, contact pressure, and peak pressure in the talofibular joint with increasing tibial osteotomy gap in groups A and B (N ¼ 10 cadavers). Mean values and 95% confidence intervals (whiskers) are shown.
62
G.W. Choi et al. / The Journal of Foot & Ankle Surgery 56 (2017) 59–64
Table 1 Estimation of changes in parameters measured by K-scan (N ¼ 10 cadavers) Parameter
Contact area (mm2) Fibular osteotomy* Tibial osteotomy gapy Force (N) Fibular osteotomy* Tibial osteotomy gapy Contact pressure (kPa) Fibular osteotomy* Tibial osteotomy gapy Peak pressure (kPa) Fibular osteotomy* Tibial osteotomy gapy
Tibiotalar Joint
Talofibular Joint
Estimation (95% CI)
p Value
Estimation (95% CI)
p Value
150.80 (39.02 to 340.62) 3.07 (13.46 to 19.62)
.12 .71
3.79 (41.88 to 49.46) 10.87 (1.46 to 20.28)
.86 .02
51.44 (116.91 to 219.80) 11.40 (19.97 to 2.84)
.53 .01
71.16 (35.32 to 107.01) 6.61 (2.27 to 10.96)
.001 .006
17.74 (31.75 to 67.23) 1.82 (7.45 to 3.82)
.46 .52
71.87 (36.65 to 107.09) 3.74 (0.46 to 7.01)
<.001 .03
85.80 (29.73 to 201.32) 0.50 (2.88 to 3.87)
.14 .76
186.60 (91.54 to 281.65) 10.31 (3.88 to 16.74)
.001 .004
Abbreviation: CI, confidence interval. * Estimated change in each parameter after tibial osteotomy without fibular osteotomy compared with tibial osteotomy with fibular osteotomy. y Estimated change in each parameter per millimeter of tibial osteotomy gap.
Testing Sequence Each specimen was tested in the following sequence: intact specimen, 3 different tibial osteotomy conditions before fibular osteotomy (the order of testing was randomized by selecting the plate randomly among the 6-, 8-, and 10-mm block plates), and 3 different tibial osteotomy conditions with combined fibular osteotomy (the testing order was randomized using the same method). The results were divided into 2 groups. The results from the tibial osteotomy only were classified as group A and those from the tibial osteotomy plus fibular osteotomy as group B.
decreased with fibular osteotomy (p ¼ .001, p < .001, and p ¼ .001, respectively) and increased with an increasing tibial osteotomy gap (p ¼ .006, p ¼ .03, and p ¼ .004, respectively; Table 1). The contact area in the talofibular joint was increased with an increasing tibial osteotomy gap (p ¼ .02) and did not change significantly with the addition of the fibular osteotomy (p ¼ .86). Radiographic Evaluation of Hindfoot Alignment and Talar Translation
Radiographic Evaluation The anteroposterior view of the ankle and long axial hindfoot view were taken at each step during the maximum load (700 N). To evaluate lateral translation of talus after supramalleolar osteotomy, the talar translation ratio was calculated by dividing the width of the talar dome medial to the axis of the tibia by the entire width of the talar dome on the anteroposterior view of the ankle. To evaluate the hindfoot alignment change after supramalleolar osteotomy, the heel alignment angle was measured by the angle between the axes of the tibia and calcaneus on the long axial hindfoot view (10). Positive values indicated varus alignment of the hindfoot.
Statistical Analysis Statistical analyses were performed using the SPSS for Windows, version. 16.0.0, software package (SPSS Inc., Chicago, IL). The linear mixed model was used to determine the effects of fibular osteotomy and tibial osteotomy gap size on the parameters measured by the K-scan and to identify whether the fibular osteotomy and tibial osteotomy gap size affected the heel alignment angle and talar translation ratio. Multiple linear regression analysis was performed in each group to determine whether changes in the heel alignment angle and talar translation ratio were related to the parameters measured by the K-scan in the talofibular joint. A p value of < .05 was considered statistically significant.
The mean heel alignment angle and talar translation ratio in both groups are shown in Fig. 4. The linear mixed model was used to identify whether the fibular osteotomy and tibial osteotomy gap size affected these 2 parameters. The heel alignment angle decreased with increasing tibial osteotomy gap (p ¼ .001) but was not affected by fibular osteotomy (p ¼ .37; Table 2). The talar translation ratio decreased with fibular osteotomy (p ¼ .01) and an increasing tibial osteotomy gap (p ¼ .02; Table 2). Multiple linear regression analysis was conducted in each group to determine whether the changes in the heel alignment angle and talar translation ratio were related to the parameters measured by the K-scan in the talofibular joint. Change in the heel alignment angle correlated positively with force transmission (regression coefficient ¼ 6.05, r2 ¼ 0.18, p ¼ .03), contact pressure (regression coefficient ¼ 0.01, r2 ¼ 0.20, p ¼ .02), and peak pressure (regression coefficient ¼ 0.02, r2 ¼ 0.18, p ¼ .03) in the talofibular joints of group A. In contrast, changes in the heel alignment angle and talar translation ratio had no relationship with any measurements in the talofibular joints of group B.
Results
Discussion
Joint Pressure Measurement
In the present study, both fibular osteotomy and tibial osteotomy gap size during medial opening-wedge supramalleolar osteotomy biomechanically affected the tibiotalar and talofibular joints differently. Fibular osteotomy had no effect on the forces transmitted or the pressures in the tibiotalar joint, but it reduced the forces transmitted and the pressures in the talofibular joint. An increase in hindfoot valgus after medial opening-wedge supramalleolar osteotomy without fibular osteotomy increased the forces transmitted and the pressures in the talofibular joint. Lee et al (9) suggested that overcorrecting talar tilt after supramalleolar osteotomy for medial ankle osteoarthritis can result in excessive hindfoot valgus with associated subfibular pain. Although lateral transfer of the load toward the fibula might occur after medial opening-wedge supramalleolar osteotomy, we could not find any
The mean contact area, force transmission, contact pressure, and peak pressure in the tibiotalar and talofibular joints are shown in Figs. 2 and 3. The linear mixed model was used to determine the effects of the fibular osteotomy and tibial osteotomy gap size on the parameters measured by the K-scan. The force transmission in the tibiotalar joint was decreased with an increasing tibial osteotomy gap (p ¼ .01), and it did not change significantly with the fibular osteotomy (p ¼ .53; Table 1). The contact area, contact pressure, and peak pressure in the tibiotalar joint were not affected by the use of fibular osteotomy (p ¼ .12, p ¼ .46, and p ¼ .14, respectively) or the tibial osteotomy gap size (p ¼ .71, p ¼ .52, and p ¼ .76, respectively). The force transmission, contact pressure, and peak pressure in the talofibular joint were
G.W. Choi et al. / The Journal of Foot & Ankle Surgery 56 (2017) 59–64
63
Fig. 4. Changes in heel alignment angle and talar translation ratio with increasing tibial osteotomy gap in groups A and B (N ¼ 10 cadavers). Mean values and 95% confidence intervals (whiskers) are shown.
biomechanical studies that measured the force transfer by way of the lateral gutter of the ankle. As the tibial osteotomy gap size increased, the heel alignment angle decreased and the contact pressure and peak pressure in the talofibular joint increased. Additionally, the force transmission in the tibiotalar joint decreased with an increasing tibial osteotomy gap, but the force transmission in the talofibular joint increased with an increasing tibial osteotomy gap. Increased contact and peak pressure in the talofibular joint can lead to subfibular pain because focal bone overload causes pain by mechanical stimulation of the nerve endings in the subchondral bone (15,16). Therefore, our results support those of previous studies (5,9) hypothesizing that the fibula might contribute to the load
transfer and valgus angulation of the hindfoot after medial openingwedge supramalleolar osteotomy can cause lateral subfibular pain. The change in heel alignment angle was positively related to the force transmission, contact pressure, and peak pressure in the talofibular joints of group A, but it had no relationship with any parameter in the talofibular joints of group B on multiple linear regression analysis. This is because combined fibular osteotomy decreased the force transmission, contact pressure, and peak pressure in the talofibular joint. This result supports the idea that medial opening-wedge supramalleolar osteotomy without fibular osteotomy can increase the risk of lateral subfibular pain postoperatively when the tibial osteotomy gap is large.
64
G.W. Choi et al. / The Journal of Foot & Ankle Surgery 56 (2017) 59–64
Table 2 Estimation of changes in radiographic parameters (N ¼ 10 cadavers) Variable Heel alignment angle ( ) Fibular osteotomy* Tibial osteotomy gapy Talar translation ratio Fibular osteotomy* Tibial osteotomy gapy
Estimation (95% CI)
p Value
1.18 (1.55 to 3.92) 0.71 (1.12 to 0.30)
.37 .001
0.06 (0.01 to 0.11) 0.01 (0.01 to 0.00)
.01 .02
Abbreviation: CI, confidence interval. * Estimated change in each parameter after tibial osteotomy without fibular osteotomy compared with tibial osteotomy with fibular osteotomy. y Estimated change in each parameter per millimeter of tibial osteotomy gap.
Medial opening-wedge supramalleolar osteotomy with fibular osteotomy can cause more lateral translation of the talus than medial opening-wedge supramalleolar osteotomy without fibular osteotomy. Combined fibular osteotomy and distal tibial osteotomy facilitates translation of the distal fragment, but the amount of shift of the osteotomized fragment is limited by the fibula after distal tibial osteotomy without fibular osteotomy (17,18). Our results coincide with these findings, showing that combined fibular osteotomy significantly decreases the talar translation ratio. Multiple linear regression analysis of the data from group A revealed that the change in heel alignment angle was associated with the force transmission, contact pressure, and peak pressure in the talofibular joint, but the change in the talar translation ratio was not associated with these parameters. Additionally, although the talus shifted more laterally after supramalleolar osteotomy in group B than that in group A, these 3 parameters were lower in group B than in group A. Therefore, the heel alignment angle seems to be related more to the force transmission, contact pressure, and peak pressure in the talofibular joint rather than to the talar translation ratio. One of the notable features of the present study was that we measured the forces acting on the tibiotalar and talofibular joints, which allowed us to identify the biomechanical effect of combined fibular osteotomy on the lateral gutter of the ankle after medial opening-wedge supramalleolar osteotomy. Previous biomechanical studies measured the forces transmitted by only the tibiotalar joint, and no biomechanical studies have measured the force transfer by way of the lateral gutter of the ankle (5,6,19,20). Another strength of the present study was that we evaluated the hindfoot alignment and talar translation using radiographs taken under load and analyzed the relationships between these radiographic parameters and the parameters measured using the K-scan. Our study had some limitations. First, the dynamic forces in the muscles and soft tissues were not simulated in this cadaveric model, which could have affected the load distribution within the ankle joint. Second, we did not reproduce the medial ankle osteoarthritis model. Medial opening-wedge supramalleolar osteotomy is used to treat medial ankle osteoarthritis. The medial joint contact forces are elevated in patients with medial ankle osteoarthritis; however, most cadaveric models in the present study had nearly normal ankle conditions. This could limit interpretation of our results. Finally, the order of the experiments was not randomized. Each specimen was tested repeatedly under normal conditions after isolated tibial osteotomy and then after combined fibular osteotomy. Through the repeated experiments, degradation of the load recovery of the sensors and
cartilage deformation could have occurred. To reduce the bias caused by these problems, the order of testing was randomized by selecting the plates randomly among the 6-, 8-, and 10-mm block plates after isolated tibial osteotomy or combined fibular osteotomy. In conclusion, in a cadaveric medial opening-wedge supramalleolar osteotomy model, an increase in tibial osteotomy gap led to increases in hindfoot valgus and pressure in the talofibular joint, although the tibiotalar joint pressure was not significantly changed with an increasing tibial osteotomy gap. Combined fibular osteotomy reduced the talofibular joint pressure that had increased after supramalleolar osteotomy, but it did not influence the tibiotalar joint pressure. Therefore, fibular osteotomy might be necessary with medial opening-wedge supramalleolar osteotomy for medial ankle arthritis to minimize the increase of pressure in the talofibular joint, especially when the osteotomy gap is large. References 1. Easley ME. Surgical treatment of the arthritic varus ankle. Foot Ankle Clin 17:665– 686, 2012. 2. Barg A, Pagenstert GI, Leumann AG, Muller AM, Henninger HB, Valderrabano V. Treatment of the arthritic valgus ankle. Foot Ankle Clin 17:647–663, 2012. 3. Tarr RR, Resnick CT, Wagner KS, Sarmiento A. Changes in tibiotalar joint contact areas following experimentally induced tibial angular deformities. Clin Orthop Relat Res 199:72–80, 1985. 4. Ting AJ, Tarr RR, Sarmiento A, Wagner K, Resnick C. The role of subtalar motion and ankle contact pressure changes from angular deformities of the tibia. Foot Ankle 7:290–299, 1987. 5. Knupp M, Stufkens SA, van Bergen CJ, Blankevoort L, Bolliger L, van Dijk CN, Hintermann B. Effect of supramalleolar varus and valgus deformities on the tibiotalar joint: a cadaveric study. Foot Ankle Int 32:609–615, 2011. 6. Stufkens SA, van Bergen CJ, Blankevoort L, van Dijk CN, Hintermann B, Knupp M. The role of the fibula in varus and valgus deformity of the tibia: a biomechanical study. J Bone Joint Surg Br 93:1232–1239, 2011. 7. Knupp M, Bolliger L, Hintermann B. Treatment of posttraumatic varus ankle deformity with supramalleolar osteotomy. Foot Ankle Clin 17:95–102, 2012. 8. Horn DM, Fragomen AT, Rozbruch SR. Supramalleolar osteotomy using circular external fixation with six-axis deformity correction of the distal tibia. Foot Ankle Int 32:986–993, 2011. 9. Lee WC, Moon JS, Lee K, Byun WJ, Lee SH. Indications for supramalleolar osteotomy in patients with ankle osteoarthritis and varus deformity. J Bone Joint Surg Am 93:1243–1248, 2011. 10. Tanaka Y, Takakura Y, Hayashi K, Taniguchi A, Kumai T, Sugimoto K. Low tibial osteotomy for varus-type osteoarthritis of the ankle. J Bone Joint Surg Br 88:909– 913, 2006. 11. Kim YS, Park EH, Koh YG, Lee JW. Supramalleolar osteotomy with bone marrow stimulation for varus ankle osteoarthritis: clinical results and second-look arthroscopic evaluation. Am J Sports Med 42:1558–1566, 2014. 12. Teramoto T, Otsuka K, Makino Y, Tashiro K, Sugitani Y. Dynamic assessments of the osteoarthritis of the ankle joint treated by distal tibial oblique osteotomy. J Jpn Soc Surg Foot 27:48–53, 2006. 13. Lee KB, Cho YJ. Oblique supramalleolar opening wedge osteotomy without fibular osteotomy for varus deformity of the ankle. Foot Ankle Int 30:565–567, 2009. 14. Myerson MS, Zide JR. Management of varus ankle osteoarthritis with jointpreserving osteotomy. Foot Ankle Clin 18:471–480, 2013. 15. Sanchis-Alfonso V. Holistic approach to understanding anterior knee pain: clinical implications. Knee Surg Sports Traumatol Arthrosc 22:2275–2285, 2014. 16. van Dijk CN, Reilingh ML, Zengerink M, van Bergen CJ. The natural history of osteochondral lesions in the ankle. Instr Course Lect 59:375–386, 2010. 17. Benthien RA, Myerson MS. Supramalleolar osteotomy for ankle deformity and arthritis. Foot Ankle Clin 9:475–487, 2004. 18. Ahn TK, Yi Y, Cho JH, Lee WC. A cohort study of patients undergoing distal tibial osteotomy without fibular osteotomy for medial ankle arthritis with mortise widening. J Bone Joint Surg Am 97:381–388, 2015. 19. Suero EM, Sabbagh Y, Westphal R, Hawi N, Citak M, Wahl FM, Krettek C, Liodakis E. Effect of medial opening wedge high tibial osteotomy on intraarticular knee and ankle contact pressures. J Orthop Res 33:598–604, 2015. 20. Schmid T, Zurbriggen S, Zderic I, Gueorguiev B, Weber M, Krause FG. Ankle joint pressure changes in a pes cavovarus model: supramalleolar valgus osteotomy versus lateralizing calcaneal osteotomy. Foot Ankle Int 34:1190–1197, 2013.
Contents lists available at ScienceDirect
The Journal of Foot & Ankle Surgery journal homepage: www.jfas.org
Effect of Combined Fibular Osteotomy on the Pressure of the Tibiotalar and Talofibular Joints in Supramalleolar Osteotomy of the Ankle: A Cadaveric Study Gi Won Choi, MD, PhD 1, Soon Hyuck Lee, MD, PhD 2, Kyung Wook Nha, MD, PhD 3, Sung Jae Lee, PhD 4, Won Hyeon Kim, BE 4, Chang-Sub Uhm, MD, PhD 5 1
Department Department Department 4 Department 5 Department 2 3
of of of of of
Orthopaedic Surgery, Korea University Ansan Hospital, Ansan-si, Gyeonggi-do, South Korea Orthopedic Surgery, Korea University Anam Hospital, Seoul, South Korea Orthopedic Surgery, Inje University Ilsanpaik Hospital, Goyang-si, Gyeonggi-do, South Korea Biomedical Engineering, Inje University, Gimhae-si, Gyeongsangnam-do, South Korea Anatomy, College of Medicine, Korea University, Seoul, South Korea
a r t i c l e i n f o
a b s t r a c t
Level of Clinical Evidence: 5
We investigated the effect of combined fibular osteotomy on the pressure of the tibiotalar and talofibular joints in medial opening-wedge supramalleolar osteotomy. Three different tibial osteotomy gaps (6, 8, and 10 mm) were created in 10 cadaveric models, and the pressure in the tibiotalar and talofibular joints was measured under axial load before and after fibular osteotomy. The heel alignment angle and talar translation ratio were evaluated radiographically. An increase in osteotomy gap led to increases in hindfoot valgus (p ¼ .001) and the contact and peak pressures in the talofibular joint (p ¼ .03 and p ¼ .004). In contrast, the contact and peak pressures in the tibiotalar joint were unchanged with an increasing osteotomy gap (p ¼ .52 and p ¼ .76). Fibular osteotomy reduced the contact and peak pressures in the talofibular joint (p < .001 and p ¼ .001, respectively), and it did not influence the contact and peak pressures in the tibiotalar joint (p ¼ .46 and p ¼ .14, respectively). Therefore, fibular osteotomy might be necessary in supramalleolar osteotomy for medial ankle arthritis to minimize the increase in pressure in the talofibular joint, especially when the osteotomy gap is large. Ó 2016 by the American College of Foot and Ankle Surgeons. All rights reserved.
Keywords: ankle joint joint contact pressure pressure sensor supramalleolar osteotomy
Supramalleolar osteotomy has been used to treat asymmetric ankle osteoarthritis with a partially preserved tibiotalar joint surface (1,2). Medial opening-wedge supramalleolar osteotomy to treat medial ankle arthritis restores joint orientation and causes a load shift to a portion of the joint that is not involved in the degenerative process, thus, improving ankle function and relieving pain (3–8). Several clinical studies have reported good results of medial opening-wedge supramalleolar osteotomy with fibular osteotomy for medial ankle arthritis (9,10), but other studies have reported good results with medial opening-wedge supramalleolar osteotomy without fibular osteotomy (11,12). Furthermore, Lee and Cho (13) suggested that their new oblique supramalleolar opening-wedge osteotomy without fibular osteotomy minimizes the adverse effects Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Soon Hyuck Lee, MD, PhD, Department of Orthopaedic Surgery, Korea University Anam Hospital, 73, Inchon-ro, Seongbuk-gu, Seoul 02841, South Korea. E-mail address: [email protected] (S.H. Lee).
of mortise distortion and enhances osteotomy site stability by the presence of an intact fibula. A combined fibular osteotomy in medial opening-wedge supramalleolar osteotomy might affect the biomechanics of the tibiotalar and talofibular joints. Angular or rotational deformity of the distal fibula plays an important role in determining the contact areas and pressure distribution at the tibiotalar joint. Also, the effect of the fibula on the biomechanics of the tibiotalar joint is more marked with valgus deformity than with varus (6). The load can be transmitted by way of the talofibular joint, and the fibula can take part in the load transfer, particularly in valgus deformities (5). Lateral subfibular pain can develop after medial opening-wedge supramalleolar osteotomy because of valgus angulation and lateral translation of the hindfoot (9). Although combined fibular osteotomy in medial opening-wedge supramalleolar osteotomy can biomechanically affect the tibiotalar and talofibular joints, the indication of fibular osteotomy has not been clearly established. Furthermore, few data have been reported regarding the biomechanical effects of combined fibular osteotomy.
1067-2516/$ - see front matter Ó 2016 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2016.08.003
60
G.W. Choi et al. / The Journal of Foot & Ankle Surgery 56 (2017) 59–64
The purpose of the present study was to investigate the effect of combined fibular osteotomy on the pressure of the tibiotalar and talofibular joints in a cadaveric medial opening-wedge supramalleolar osteotomy model. We hypothesized that the talofibular joint pressure would increase after medial opening-wedge supramalleolar osteotomy without fibular osteotomy and that combined fibular osteotomy would reduce the increase in talofibular joint pressure. Materials and Methods
Specimen Preparation and Testing Setup Ten fresh-frozen, above-the-knee amputation specimens were obtained from 4 male donors and 1 female donor, with a mean age of 72 (range 56 to 85) years. Bony malalignment was excluded radiologically, and a normal range of motion in the ankle joint was verified in all specimens. Before the experiment, all the specimens were thawed at room temperature for 24 hours. The knee joints were disarticulated, preserving the intact tibiofibular joint. The skin, subcutaneous tissue, and muscles of the proximal tibiofibular joint and ankle joint were removed with preservation of the interosseous membranes and ligaments. The tibial plateau was transected, and the customized plate with a stem was inserted into the tibia after reaming the intramedullary canal. Additionally, two 6.5-mm Asnis III cannulated screws (Stryker, Mahwah, NJ) were inserted through the 2 holes on both sides of the stem. The specimen fixed to the plate was attached to a loading machine (FMS-2500-L2P force measurement system; LS Starrett Co., Athol, MA) using a ball-socket jig, which allows free axial rotation and angulation of the tibia under axial load (Fig. 1). The point of the load axis on the foot plate was marked as the point of intersection of vertical and horizontal lines. To match the talar dome center to the load axis, the talar dome center was positioned to coincide with both vertical and horizontal lines on the foot plate. The heel was buttressed by a lateral block to prevent the heel from sliding laterally, and the forefoot was stabilized with a strap. The K-Scan 4000 system (Tekscan, South Boston, MA) was used to measure the pressure and force in the tibiotalar and talofibular joints. It consists of scanning electronics, software, and flexible thin-film (0.10-mm) sensors. The sensor has 2 identical, independent sensing arrays. Each sensing array is composed of printed circuits with grids of load-sensing regions. A “sensel” refers to each load-sensing region within the
grid. Each sensing array has a total 920.7-mm2 matrix area (27.9 mm 33.0 mm), 572 sensels, and a density of 62.0 sensels/cm2. Anterior and posterior ankle arthrotomies were performed to insert 1 sensor into the tibiotalar joint. The anterior and posterior talofibular ligaments were divided to insert the other sensor into the talofibular joint, and they were repaired with nylon 3-0 sutures after inserting the sensor. To avoid the sensors breaking away from the joints, the edges of the sensors were sutured to the surrounding periosteum and capsular tissues of the 2 joints anteriorly and posteriorly with Vicryl 2-0 suture. A maximal load of 700 N was applied to simulate a single-leg stance with mean body weight (13). After 15 preconditioning cycles with a 700-N load, the static axial load was increased continuously from a 50 N preload to 700 N. The maximum load was maintained for 2 seconds, and peak pressures were captured at 50 Hz. The pressure magnitude and distribution, contact area, and force transmitted were measured using K-Scan 4000 software (Tekscan).
Osteotomy Procedures For the medial opening-wedge supramalleolar osteotomy, the osteotomy plane was initiated 4 to 5 cm proximal to the tip of the medial malleolus and directed obliquely toward the syndesmosis, preserving the lateral cortex of the tibia (9,11,13). To create 3 different heights of the osteotomy gap, the osteotomy was stabilized using the H-plate (Arthrex, Naples, FL), which has 3 different block heights (6, 8, and 10 mm) after medial opening of the osteotomy. To prevent displacement of the osteotomy gap during the experimental axial load, a unilateral external fixator was also applied to the medial aspect of distal tibia. After measuring the joint contact pressures under 3 different tibial osteotomy conditions (6-, 8-, and 10-mm osteotomy gaps), a fibular osteotomy was performed in an inferomedial direction at the same level as that of the tibial osteotomy (9,14). After bending a one-third tubular plate to fit the valgus angulation of the fibular osteotomy site, which was determined by the height of the osteotomy gap, the plate was fixed with screws. Therefore, 7 different conditions were created in each specimen according to the combined fibular osteotomy and tibial osteotomy gap size as follows: 1. 2. 3. 4. 5. 6. 7.
Intact specimen (before osteotomy) Tibial osteotomy gap of 6 mm Tibial osteotomy gap of 8 mm Tibial osteotomy gap of 10 mm Tibial osteotomy gap of 6 mm with fibular osteotomy Tibial osteotomy gap of 8 mm with fibular osteotomy Tibial osteotomy gap of 10 mm with fibular osteotomy
Fig. 1. Experimental setup. The specimen was fixed with the customized plate attached to the loading machine. Two identical, independent Tekscan pressure sensors were placed in the tibiotalar and talofibular joints, respectively.
G.W. Choi et al. / The Journal of Foot & Ankle Surgery 56 (2017) 59–64
Fig. 2. Changes in contact area, force transmission, contact pressure, and peak pressure in the tibiotalar joint with increasing tibial osteotomy gap in groups A and B (N ¼ 10 cadavers). Mean values and 95% confidence intervals (whiskers) are shown.
61
Fig. 3. Changes in contact area, force transmission, contact pressure, and peak pressure in the talofibular joint with increasing tibial osteotomy gap in groups A and B (N ¼ 10 cadavers). Mean values and 95% confidence intervals (whiskers) are shown.
62
G.W. Choi et al. / The Journal of Foot & Ankle Surgery 56 (2017) 59–64
Table 1 Estimation of changes in parameters measured by K-scan (N ¼ 10 cadavers) Parameter
Contact area (mm2) Fibular osteotomy* Tibial osteotomy gapy Force (N) Fibular osteotomy* Tibial osteotomy gapy Contact pressure (kPa) Fibular osteotomy* Tibial osteotomy gapy Peak pressure (kPa) Fibular osteotomy* Tibial osteotomy gapy
Tibiotalar Joint
Talofibular Joint
Estimation (95% CI)
p Value
Estimation (95% CI)
p Value
150.80 (39.02 to 340.62) 3.07 (13.46 to 19.62)
.12 .71
3.79 (41.88 to 49.46) 10.87 (1.46 to 20.28)
.86 .02
51.44 (116.91 to 219.80) 11.40 (19.97 to 2.84)
.53 .01
71.16 (35.32 to 107.01) 6.61 (2.27 to 10.96)
.001 .006
17.74 (31.75 to 67.23) 1.82 (7.45 to 3.82)
.46 .52
71.87 (36.65 to 107.09) 3.74 (0.46 to 7.01)
<.001 .03
85.80 (29.73 to 201.32) 0.50 (2.88 to 3.87)
.14 .76
186.60 (91.54 to 281.65) 10.31 (3.88 to 16.74)
.001 .004
Abbreviation: CI, confidence interval. * Estimated change in each parameter after tibial osteotomy without fibular osteotomy compared with tibial osteotomy with fibular osteotomy. y Estimated change in each parameter per millimeter of tibial osteotomy gap.
Testing Sequence Each specimen was tested in the following sequence: intact specimen, 3 different tibial osteotomy conditions before fibular osteotomy (the order of testing was randomized by selecting the plate randomly among the 6-, 8-, and 10-mm block plates), and 3 different tibial osteotomy conditions with combined fibular osteotomy (the testing order was randomized using the same method). The results were divided into 2 groups. The results from the tibial osteotomy only were classified as group A and those from the tibial osteotomy plus fibular osteotomy as group B.
decreased with fibular osteotomy (p ¼ .001, p < .001, and p ¼ .001, respectively) and increased with an increasing tibial osteotomy gap (p ¼ .006, p ¼ .03, and p ¼ .004, respectively; Table 1). The contact area in the talofibular joint was increased with an increasing tibial osteotomy gap (p ¼ .02) and did not change significantly with the addition of the fibular osteotomy (p ¼ .86). Radiographic Evaluation of Hindfoot Alignment and Talar Translation
Radiographic Evaluation The anteroposterior view of the ankle and long axial hindfoot view were taken at each step during the maximum load (700 N). To evaluate lateral translation of talus after supramalleolar osteotomy, the talar translation ratio was calculated by dividing the width of the talar dome medial to the axis of the tibia by the entire width of the talar dome on the anteroposterior view of the ankle. To evaluate the hindfoot alignment change after supramalleolar osteotomy, the heel alignment angle was measured by the angle between the axes of the tibia and calcaneus on the long axial hindfoot view (10). Positive values indicated varus alignment of the hindfoot.
Statistical Analysis Statistical analyses were performed using the SPSS for Windows, version. 16.0.0, software package (SPSS Inc., Chicago, IL). The linear mixed model was used to determine the effects of fibular osteotomy and tibial osteotomy gap size on the parameters measured by the K-scan and to identify whether the fibular osteotomy and tibial osteotomy gap size affected the heel alignment angle and talar translation ratio. Multiple linear regression analysis was performed in each group to determine whether changes in the heel alignment angle and talar translation ratio were related to the parameters measured by the K-scan in the talofibular joint. A p value of < .05 was considered statistically significant.
The mean heel alignment angle and talar translation ratio in both groups are shown in Fig. 4. The linear mixed model was used to identify whether the fibular osteotomy and tibial osteotomy gap size affected these 2 parameters. The heel alignment angle decreased with increasing tibial osteotomy gap (p ¼ .001) but was not affected by fibular osteotomy (p ¼ .37; Table 2). The talar translation ratio decreased with fibular osteotomy (p ¼ .01) and an increasing tibial osteotomy gap (p ¼ .02; Table 2). Multiple linear regression analysis was conducted in each group to determine whether the changes in the heel alignment angle and talar translation ratio were related to the parameters measured by the K-scan in the talofibular joint. Change in the heel alignment angle correlated positively with force transmission (regression coefficient ¼ 6.05, r2 ¼ 0.18, p ¼ .03), contact pressure (regression coefficient ¼ 0.01, r2 ¼ 0.20, p ¼ .02), and peak pressure (regression coefficient ¼ 0.02, r2 ¼ 0.18, p ¼ .03) in the talofibular joints of group A. In contrast, changes in the heel alignment angle and talar translation ratio had no relationship with any measurements in the talofibular joints of group B.
Results
Discussion
Joint Pressure Measurement
In the present study, both fibular osteotomy and tibial osteotomy gap size during medial opening-wedge supramalleolar osteotomy biomechanically affected the tibiotalar and talofibular joints differently. Fibular osteotomy had no effect on the forces transmitted or the pressures in the tibiotalar joint, but it reduced the forces transmitted and the pressures in the talofibular joint. An increase in hindfoot valgus after medial opening-wedge supramalleolar osteotomy without fibular osteotomy increased the forces transmitted and the pressures in the talofibular joint. Lee et al (9) suggested that overcorrecting talar tilt after supramalleolar osteotomy for medial ankle osteoarthritis can result in excessive hindfoot valgus with associated subfibular pain. Although lateral transfer of the load toward the fibula might occur after medial opening-wedge supramalleolar osteotomy, we could not find any
The mean contact area, force transmission, contact pressure, and peak pressure in the tibiotalar and talofibular joints are shown in Figs. 2 and 3. The linear mixed model was used to determine the effects of the fibular osteotomy and tibial osteotomy gap size on the parameters measured by the K-scan. The force transmission in the tibiotalar joint was decreased with an increasing tibial osteotomy gap (p ¼ .01), and it did not change significantly with the fibular osteotomy (p ¼ .53; Table 1). The contact area, contact pressure, and peak pressure in the tibiotalar joint were not affected by the use of fibular osteotomy (p ¼ .12, p ¼ .46, and p ¼ .14, respectively) or the tibial osteotomy gap size (p ¼ .71, p ¼ .52, and p ¼ .76, respectively). The force transmission, contact pressure, and peak pressure in the talofibular joint were
G.W. Choi et al. / The Journal of Foot & Ankle Surgery 56 (2017) 59–64
63
Fig. 4. Changes in heel alignment angle and talar translation ratio with increasing tibial osteotomy gap in groups A and B (N ¼ 10 cadavers). Mean values and 95% confidence intervals (whiskers) are shown.
biomechanical studies that measured the force transfer by way of the lateral gutter of the ankle. As the tibial osteotomy gap size increased, the heel alignment angle decreased and the contact pressure and peak pressure in the talofibular joint increased. Additionally, the force transmission in the tibiotalar joint decreased with an increasing tibial osteotomy gap, but the force transmission in the talofibular joint increased with an increasing tibial osteotomy gap. Increased contact and peak pressure in the talofibular joint can lead to subfibular pain because focal bone overload causes pain by mechanical stimulation of the nerve endings in the subchondral bone (15,16). Therefore, our results support those of previous studies (5,9) hypothesizing that the fibula might contribute to the load
transfer and valgus angulation of the hindfoot after medial openingwedge supramalleolar osteotomy can cause lateral subfibular pain. The change in heel alignment angle was positively related to the force transmission, contact pressure, and peak pressure in the talofibular joints of group A, but it had no relationship with any parameter in the talofibular joints of group B on multiple linear regression analysis. This is because combined fibular osteotomy decreased the force transmission, contact pressure, and peak pressure in the talofibular joint. This result supports the idea that medial opening-wedge supramalleolar osteotomy without fibular osteotomy can increase the risk of lateral subfibular pain postoperatively when the tibial osteotomy gap is large.
64
G.W. Choi et al. / The Journal of Foot & Ankle Surgery 56 (2017) 59–64
Table 2 Estimation of changes in radiographic parameters (N ¼ 10 cadavers) Variable Heel alignment angle ( ) Fibular osteotomy* Tibial osteotomy gapy Talar translation ratio Fibular osteotomy* Tibial osteotomy gapy
Estimation (95% CI)
p Value
1.18 (1.55 to 3.92) 0.71 (1.12 to 0.30)
.37 .001
0.06 (0.01 to 0.11) 0.01 (0.01 to 0.00)
.01 .02
Abbreviation: CI, confidence interval. * Estimated change in each parameter after tibial osteotomy without fibular osteotomy compared with tibial osteotomy with fibular osteotomy. y Estimated change in each parameter per millimeter of tibial osteotomy gap.
Medial opening-wedge supramalleolar osteotomy with fibular osteotomy can cause more lateral translation of the talus than medial opening-wedge supramalleolar osteotomy without fibular osteotomy. Combined fibular osteotomy and distal tibial osteotomy facilitates translation of the distal fragment, but the amount of shift of the osteotomized fragment is limited by the fibula after distal tibial osteotomy without fibular osteotomy (17,18). Our results coincide with these findings, showing that combined fibular osteotomy significantly decreases the talar translation ratio. Multiple linear regression analysis of the data from group A revealed that the change in heel alignment angle was associated with the force transmission, contact pressure, and peak pressure in the talofibular joint, but the change in the talar translation ratio was not associated with these parameters. Additionally, although the talus shifted more laterally after supramalleolar osteotomy in group B than that in group A, these 3 parameters were lower in group B than in group A. Therefore, the heel alignment angle seems to be related more to the force transmission, contact pressure, and peak pressure in the talofibular joint rather than to the talar translation ratio. One of the notable features of the present study was that we measured the forces acting on the tibiotalar and talofibular joints, which allowed us to identify the biomechanical effect of combined fibular osteotomy on the lateral gutter of the ankle after medial opening-wedge supramalleolar osteotomy. Previous biomechanical studies measured the forces transmitted by only the tibiotalar joint, and no biomechanical studies have measured the force transfer by way of the lateral gutter of the ankle (5,6,19,20). Another strength of the present study was that we evaluated the hindfoot alignment and talar translation using radiographs taken under load and analyzed the relationships between these radiographic parameters and the parameters measured using the K-scan. Our study had some limitations. First, the dynamic forces in the muscles and soft tissues were not simulated in this cadaveric model, which could have affected the load distribution within the ankle joint. Second, we did not reproduce the medial ankle osteoarthritis model. Medial opening-wedge supramalleolar osteotomy is used to treat medial ankle osteoarthritis. The medial joint contact forces are elevated in patients with medial ankle osteoarthritis; however, most cadaveric models in the present study had nearly normal ankle conditions. This could limit interpretation of our results. Finally, the order of the experiments was not randomized. Each specimen was tested repeatedly under normal conditions after isolated tibial osteotomy and then after combined fibular osteotomy. Through the repeated experiments, degradation of the load recovery of the sensors and
cartilage deformation could have occurred. To reduce the bias caused by these problems, the order of testing was randomized by selecting the plates randomly among the 6-, 8-, and 10-mm block plates after isolated tibial osteotomy or combined fibular osteotomy. In conclusion, in a cadaveric medial opening-wedge supramalleolar osteotomy model, an increase in tibial osteotomy gap led to increases in hindfoot valgus and pressure in the talofibular joint, although the tibiotalar joint pressure was not significantly changed with an increasing tibial osteotomy gap. Combined fibular osteotomy reduced the talofibular joint pressure that had increased after supramalleolar osteotomy, but it did not influence the tibiotalar joint pressure. Therefore, fibular osteotomy might be necessary with medial opening-wedge supramalleolar osteotomy for medial ankle arthritis to minimize the increase of pressure in the talofibular joint, especially when the osteotomy gap is large. References 1. Easley ME. Surgical treatment of the arthritic varus ankle. Foot Ankle Clin 17:665– 686, 2012. 2. Barg A, Pagenstert GI, Leumann AG, Muller AM, Henninger HB, Valderrabano V. Treatment of the arthritic valgus ankle. Foot Ankle Clin 17:647–663, 2012. 3. Tarr RR, Resnick CT, Wagner KS, Sarmiento A. Changes in tibiotalar joint contact areas following experimentally induced tibial angular deformities. Clin Orthop Relat Res 199:72–80, 1985. 4. Ting AJ, Tarr RR, Sarmiento A, Wagner K, Resnick C. The role of subtalar motion and ankle contact pressure changes from angular deformities of the tibia. Foot Ankle 7:290–299, 1987. 5. Knupp M, Stufkens SA, van Bergen CJ, Blankevoort L, Bolliger L, van Dijk CN, Hintermann B. Effect of supramalleolar varus and valgus deformities on the tibiotalar joint: a cadaveric study. Foot Ankle Int 32:609–615, 2011. 6. Stufkens SA, van Bergen CJ, Blankevoort L, van Dijk CN, Hintermann B, Knupp M. The role of the fibula in varus and valgus deformity of the tibia: a biomechanical study. J Bone Joint Surg Br 93:1232–1239, 2011. 7. Knupp M, Bolliger L, Hintermann B. Treatment of posttraumatic varus ankle deformity with supramalleolar osteotomy. Foot Ankle Clin 17:95–102, 2012. 8. Horn DM, Fragomen AT, Rozbruch SR. Supramalleolar osteotomy using circular external fixation with six-axis deformity correction of the distal tibia. Foot Ankle Int 32:986–993, 2011. 9. Lee WC, Moon JS, Lee K, Byun WJ, Lee SH. Indications for supramalleolar osteotomy in patients with ankle osteoarthritis and varus deformity. J Bone Joint Surg Am 93:1243–1248, 2011. 10. Tanaka Y, Takakura Y, Hayashi K, Taniguchi A, Kumai T, Sugimoto K. Low tibial osteotomy for varus-type osteoarthritis of the ankle. J Bone Joint Surg Br 88:909– 913, 2006. 11. Kim YS, Park EH, Koh YG, Lee JW. Supramalleolar osteotomy with bone marrow stimulation for varus ankle osteoarthritis: clinical results and second-look arthroscopic evaluation. Am J Sports Med 42:1558–1566, 2014. 12. Teramoto T, Otsuka K, Makino Y, Tashiro K, Sugitani Y. Dynamic assessments of the osteoarthritis of the ankle joint treated by distal tibial oblique osteotomy. J Jpn Soc Surg Foot 27:48–53, 2006. 13. Lee KB, Cho YJ. Oblique supramalleolar opening wedge osteotomy without fibular osteotomy for varus deformity of the ankle. Foot Ankle Int 30:565–567, 2009. 14. Myerson MS, Zide JR. Management of varus ankle osteoarthritis with jointpreserving osteotomy. Foot Ankle Clin 18:471–480, 2013. 15. Sanchis-Alfonso V. Holistic approach to understanding anterior knee pain: clinical implications. Knee Surg Sports Traumatol Arthrosc 22:2275–2285, 2014. 16. van Dijk CN, Reilingh ML, Zengerink M, van Bergen CJ. The natural history of osteochondral lesions in the ankle. Instr Course Lect 59:375–386, 2010. 17. Benthien RA, Myerson MS. Supramalleolar osteotomy for ankle deformity and arthritis. Foot Ankle Clin 9:475–487, 2004. 18. Ahn TK, Yi Y, Cho JH, Lee WC. A cohort study of patients undergoing distal tibial osteotomy without fibular osteotomy for medial ankle arthritis with mortise widening. J Bone Joint Surg Am 97:381–388, 2015. 19. Suero EM, Sabbagh Y, Westphal R, Hawi N, Citak M, Wahl FM, Krettek C, Liodakis E. Effect of medial opening wedge high tibial osteotomy on intraarticular knee and ankle contact pressures. J Orthop Res 33:598–604, 2015. 20. Schmid T, Zurbriggen S, Zderic I, Gueorguiev B, Weber M, Krause FG. Ankle joint pressure changes in a pes cavovarus model: supramalleolar valgus osteotomy versus lateralizing calcaneal osteotomy. Foot Ankle Int 34:1190–1197, 2013.