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Radiographic changes of the mid-tarsal joint after calcaneal lengthening for planovalgus foot deformity
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Foot and Ankle Surgery xxx (2018) xxx–xxx
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Radiographic changes of the mid-tarsal joint after calcaneal lengthening for planovalgus foot deformity Ki Hyuk Sunga,1, Soon-Sun Kwonb,1, Chin Youb Chunga , Kyoung Min Leea , Moon Seok Parka,* a Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, 82 Gumi-ro 173 Beon-gil, Bundang-Gu, Seongnam, Gyeonggi 13620, South Korea b Department of Mathematics, College of Natural Sciences, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon, Gyeonggi 16499, South Korea
A R T I C L E I N F O
A B S T R A C T
Article history: Received 16 October 2018 Received in revised form 16 November 2018 Accepted 21 December 2018 Available online xxx
Background: This study evaluate the radiographic changes in the mid-tarsal joint, including the calcaneocuboid and talonavicular (TN) joints after calcaneal lengthening for planovalgus deformity in children. Methods: This study included 38 patients (68 feet) who underwent calcaneal lengthening for planovalgus deformity. Radiographic osteoarthritic changes at the CC or TN joint were defined as modified Kellgren– Lawrence grade of 1. Results: Among the 68 feet, 31 feet (45.6%) showed radiographic osteoarthritic changes at the CC joint and 20 (29.4%) showed changes at the TN joint. Risk of radiographic osteoarthritic changes at the CC joint was associated with increased age at surgery (OR = 1.2, p = 0.038). Risk of radiographic osteoarthritic changes at the TN joint was associated with increased age at surgery (OR = 2.2; p = 0.002), preoperative AP talus-1st metatarsal angle (OR = 1.1; p = 0.044), and degree of CC subluxation (OR = 2.1; p = 0.007). Conclusions: Surgeons should consider the risk factors in the surgical correction of planovalgus deformity to prevent mid-tarsal arthritis. © 2018 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.
Keywords: Calcaneal lengthening Planovalgus deformity Mid-tarsal joint Radiographic osteoarthritic change
1. Introduction In children and adolescents, planovalgus foot deformity is characterized by complex features including hindfoot valgus, midfoot planus/pronation, and forefoot abduction/supination with a relatively short lateral column [1,2]. Most children with planovalgus deformities are asymptomatic and do not require treatment. When the deformity becomes symptomatic and leads to pain while weight-bearing, callus formation, or ulcerative lesions as a result of talar head prominence and functional impairment, it will require treatment [3,4]. Idiopathic planovalgus is known to improve spontaneously as children grow older [5], but surgical treatment is considered when the patient does not respond to conservative treatment [4,6,7]. Many surgical procedures such as arthrodesis, arthroereisis, lengthening of the lateral column, and calcaneal medial displacement osteotomy have been suggested [3,8]. Of these,
calcaneal lengthening is an effective surgical treatment for planovalgus foot deformity in children [4,6,7,9–12]. However, concerns have been raised in relation to calcaneocuboid (CC) joint subluxation and increased CC joint pressure after calcaneal lengthening [1,4,8,13], which may lead to degenerative arthritis of the CC joint [13,14]. The incidence of degenerative changes in the CC joint after calcaneal lengthening was reported at 0–91.3% [1,13–15]. However, most previous studies on calcaneal lengthening focused only on the CC joint and did not investigate long-term changes in the midtarsal joint, which includes the CC and talonavicular (TN) joints. Therefore, the present study aimed to evaluate the radiographic changes in the mid-tarsal joint including the CC and TN joints after calcaneal lengthening for planovalgus foot deformity in children, and to identify the risk factors for such changes. We hypothesized that a degenerative change at the mid-tarsal joint would develop after calcaneal lengthening. 2. Material and methods
* Corresponding author. E-mail addresses: [email protected] (K.H. Sung), [email protected] (S.-S. Kwon), [email protected] (C.Y. Chung), [email protected] (K.M. Lee), [email protected] (M.S. Park). 1 These authors contributed equally to the writing of this article.
This retrospective study was approved by the institutional review board at our institution. The need for informed consent was waived because of the retrospective design of the study.
https://doi.org/10.1016/j.fas.2018.12.008 1268-7731/© 2018 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: K.H. Sung, et al., Radiographic changes of the mid-tarsal joint after calcaneal lengthening for planovalgus foot deformity, Foot Ankle Surg (2018), https://doi.org/10.1016/j.fas.2018.12.008
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2.1. Patients
2.3. Consensus-building and radiographic parameters
Patients who underwent calcaneal lengthening for planovalgus deformity between May 2003 and January 2012 were enrolled in our study according to the following inclusion criteria: age <20 years; minimum follow-up of 5 years; availability of preoperative and postoperative anteroposterior (AP) and lateral (LAT) weightbearing foot radiographs. The exclusion criteria were as follows: concurrent medial column procedures such as medial cuneiform osteotomy, TN capsular plication, tibialis posterior tendon reefing, or TN fusion; foot radiographs inadequate for assessment. Data regarding the patients’ age at surgery, sex, diagnosis (cerebral palsy or idiopathic), affected side (right or left), and duration of followup were obtained by reviewing the medical records in our hospital’s database. Between May 2003 and January 2012, we performed 405 calcaneal lengthening operations in 231 patients with planovalgus deformity. Four patients (8 feet) were excluded due to lack of adequate foot radiographs and 189 patients (329 feet) were excluded due to inadequate follow-up duration (<5 years). Therefore, 38 patients (68 feet) were finally included in our study, and 204 AP and LAT standing foot radiographs were assessed. The etiology was cerebral palsy in 25 patients (44 feet) and idiopathic in 13 patients (24 feet). Among the patients with cerebral palsy, 19 underwent bilateral surgery and 6 underwent unilateral surgery. Among the patients with idiopathic etiology, 11 underwent bilateral surgery and 2 underwent unilateral surgery (Table 1).
Before the radiographic measurements, a consensus-building session to select and define suitable radiographic parameters was held by five orthopedic surgeons, who had an experience in orthopedic surgery (30, 17, 15, 13, and 7 years, respectively). Previous studies were reviewed, [2,11,12,16–18] and four parameters considered to have clinical relevance in quantifying planovalgus foot deformity were selected for the radiographic measurements. To assess the radiographic osteoarthritic changes in the CC and TN joints, the modified Kellgren–Lawrence (K–L) scoring system was used [19–21]. K–L grade has high intraobserver reliability [21]. The radiographic evaluation included weight-bearing AP and LAT foot radiographs obtained using a UT 2000 X-ray machine (Philips Research, Eindhoven, The Netherlands), with a source-toimage distance of approximately 100 cm. The X-ray machine settings were 46–50 kVp and 4.5–5 mA s, depending on patient body size. All conventional radiographic images were digitally acquired using picture archiving and communication software (INFINITT Healthcare, Seoul, Korea), which was subsequently used for measurements. On the LAT weight-bearing radiographs, calcaneal pitch angle, LAT talus-first metatarsal angle, and degree of CC subluxation were measured [2]. The calcaneal pitch angle was defined as the angle between a line drawn along the edge of the plantar soft tissue shadow and a line drawn along the lower margin of the calcaneus. The LAT talus-first metatarsal angle was defined as the angle between a line bisecting the long axis of the first metatarsal bone and a line drawn through the midpoints of the talar head and neck. The degree of CC subluxation was defined as the angle between a line drawn through the midpoint of the articular surface of the calcaneus and the most posterior aspect of the calcaneus, and a line drawn through the midpoint of the articular surface of the cuboid and the most posterior aspect of the calcaneus (Fig. 1). The modified K–L grade of the CC and TN joints was decided based on osteophyte formation and joint space narrowing compared to the first metatarsocuneiform joint (Table 2,Fig. 2). Osteophyte size was measured as the degree of protrusion from the anterior margin of the talus or calcaneus. The presence of a bony spur at the talus or calcaneus was also recorded. Radiographic osteoarthritic changes in the CC or TN joint were defined as the modified K–L grade 1 or above. On the AP weight-bearing radiographs, the AP talus-first metatarsal angle was measured as the angle between a line
2.2. Operative procedure Operative treatment was indicated for patients in whom conservative treatment failed and who had a significant deformity that was either painful or limited function. Calcaneal lengthening was performed by two pediatric orthopedic surgeons (CYC, MSP) who followed the same protocol. The surgical procedure used was a minor modification of the Evans technique [4]. Using an oscillating saw, transverse osteotomy was performed between the anterior and the middle facets of the calcaneus, 1.5 cm proximal to the CC joint. Under fluoroscopic guidance, the osteotomy surfaces of the proximal and distal calcaneal fragments were widened using a laminar spreader until anatomic reduction of the subtalar and TN joints was achieved. A commercially available human iliac crest allograft bone wedge was trimmed into a trapezoidal shape, sized to fit the osteotomy site, and inserted in the distracted area. Stabilization of the bone graft or CC joint was not performed. The peroneus brevis tendon was lengthened using Z-plasty, but the peroneus longus tendon was not lengthened. In patients with equinus deformity, concomitant tendo-Achilles lengthening or Strayer procedure was performed. After the surgery, the operated foot was immobilized with a short leg cast, and the non-weight bearing period was set at a minimum of 6 weeks. After radiographic union was confirmed, standing and weight-bearing were resumed with a leaf spring-type ankle-foot orthosis, which was worn for 3 months.
Table 1 Summary of patient demographics and clinical characteristics. Parameters
Values
Sex (male/female) Age at surgery (years) Follow-up duration (years) Laterality (bilateral/unilateral) Etiology (Cerebral palsy/idiopathic)
23/15 11 4 (range: 5–19) 8 3 (range: 5–13) 30/8 25/13
Fig. 1. Definition of radiographic parameters measured on lateral weight-bearing radiographs of the foot. The calcaneal pitch angle (CP) is defined as the angle between a line drawn along the edge of the plantar soft tissue shadow and a line drawn along the lower margin of the calcaneus. The lateral talus-first metatarsal angle (Lat talo-1MT) is defined as the angle between a line bisecting the long axis of the first metatarsal bone and a line drawn through the midpoints of the talar head and neck. Calcaneocuboid subluxation is defined as the angle between a line drawn through the midpoint of the articular surface of the calcaneus and the most posterior aspect of the calcaneus (A), and a line drawn through the midpoint of the articular surface of the cuboid and the most posterior aspect of the calcaneus (B).
Please cite this article in press as: K.H. Sung, et al., Radiographic changes of the mid-tarsal joint after calcaneal lengthening for planovalgus foot deformity, Foot Ankle Surg (2018), https://doi.org/10.1016/j.fas.2018.12.008
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K.H. Sung et al. / Foot and Ankle Surgery xxx (2018) xxx–xxx Table 2 Grading Scales for the Radiographic Osteoarthritis Classification System of talonavicular and calcaneocuboid joint by Modified Kellgren–Lawrence grade19–21. Grade
0 1 2 3 4
Radiographic signs Osteophyte formation
Joint space narrowing
<1 mm 1–2 mm 2–4 mm 4–6 mm 6 mm
<25% 25–50% 50–75% 75% Obliteration
The modified Kellgren–Lawrence grade was determined based on either osteophyte formation or joint space narrowing when compared to the first metatarsocuneiform joint.
drawn through the midpoints of the talar head and neck, and a line bisecting the long axis of the first metatarsal bone (Fig. 3).
3
estimating equation (GEE) was employed for statistical analysis [25]. To identify the risk factors for long-term osteoarthritic changes following surgical treatment for planovalgus foot deformity, the associations between potential risk factors and the modified K–L grade at the CC and TN joints or the presence of a bony spur were assessed using GEE-based multivariate analysis to calculate the adjusted odds ratios (ORs) and 95% CIs. In the model, the patient age at surgery, sex, diagnosis, and radiographic parameters were treated as fixed effects, while the individual subjects and affected side were treated as random effects. While the working covariance structure could assume different types according to the model, we used compound symmetry covariance structure. Statistical analyses were conducted using R version 3.2.5 (R Foundation for Statistical Computing, Vienna, Austria). All tests were two-tailed, and p-values < 0.05 were considered to indicate significance.
2.4. Reliability testing and radiographic measurement 3. Results After consensus-building, reliability testing was conducted prior to performing the measurements included in our analysis. Two orthopedic surgeons (13 and 4 years of experience in orthopedic surgery, respectively) assessed the interobserver reliability of the radiographic measurements by independently measuring the radiographic parameters for 15 feet, while blinded to the patients’ clinical information and to the measurements reported by other examiners. After reliability testing for each radiographic parameter, all measurements on the preoperative, 1 year postoperative and final follow-up radiographs were performed by one orthopedic surgeon. 2.5. Statistical analysis The intraclass correlation coefficients (ICCs) and their 95% confidence intervals (CIs) were used to summarize the interobserver reliabilities of radiographic measurements, and were calculated in the setting of a two-way mixed-effect model, assuming a single measurement and absolute agreement [22,23]. With an ICC target value of 0.9, a Bonett approximation was used with 0.2 set as the width of the 95% CIs [24]. The minimum sample size required for detecting clinically meaningful differences was calculated to be 15 feet. Preoperative radiographic measurements were compared with values obtained at 1 year postoperatively and at final follow-up using repeated-measures analysis of variance (ANOVA) with a Bonferroni post-hoc test. To consider bilateral case, a generalized
All radiographic parameters showed excellent reliability (ICC, 0.911–0.980). AP talus-first metatarsal angle, LAT talus-first metatarsal angle, and calcaneal pitch angle improved significantly after surgery (all p < 0.001). While no further changes in AP talusfirst metatarsal angle or LAT talus-first metatarsal angle were noted at final follow-up (p = 0.066 and 1.000, respectively), calcaneal pitch angle decreased significantly between the 1-year follow-up and final follow-up (p = 0.001). Similarly, the degree of CC subluxation increased significantly after surgery (p < 0.001) but had decreased at final follow-up (p < 0.001) (Table 3). A bony spur was noted at the CC joint in 5 feet (7.4%) and at the TN joint in 8 feet (11.8%). Radiographic osteoarthritic changes were noted at the CC joint in 31 feet (45.6%; modified K–L grade: 1 in 25 feet, 2 in 6 feet) and at the TN joint in 20 feet (29.4%; (modified K–L grade: 1 in 11 feet, 2 in 9 feet). Nine feet (13.2%) had a bony spur at the CC or TN joint, and 37 feet (54.4%) showed radiographic osteoarthritic changes at the CC or TN joint (Table 4). The risk of radiographic osteoarthritic changes at the CC joint increased with age at surgery (OR, 1.2; 95% CI, 1.0–1.4; p = 0.038) but was not associated with sex, affected side, diagnosis, or radiographic parameters. The risk of radiographic osteoarthritis at the TN joint also increased with age at surgery (OR, 2.2; 95% CI,1.3–3.5; p = 0.002), but was furthermore significantly associated with preoperative AP talus-first metatarsal angle (OR, 1.1; 95% CI, 1.0–1.2; p = 0.044) and degree of CC subluxation (OR, 2.1; 95% CI, 1.2–3.7; p = 0.007). Presence of a bony spur at the calcaneus was significantly associated
Fig. 2. Modified Kellgren–Lawrence grade of the calcaneocuboid and talonavicular joints was decided based on osteophyte formation and joint space narrowing. Osteophyte size (A) was measured as the degree of protrusion from the anterior margin of the talus or calcaneus. Joint space narrowing of calcaneocuboid or talonavicualr joints (B) were compared to the width of first metatarsocuneiform joint (C).
Please cite this article in press as: K.H. Sung, et al., Radiographic changes of the mid-tarsal joint after calcaneal lengthening for planovalgus foot deformity, Foot Ankle Surg (2018), https://doi.org/10.1016/j.fas.2018.12.008
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Fig. 3. Definition of radiographic parameters measured on anteroposterior weightbearing radiographs of the foot. The anteroposterior talus-first metatarsal angle is defined as the angle between a line drawn through the midpoints of the talar head and neck (A) and a line bisecting the long axis of the first metatarsal bone (B).
with sex, diagnosis, age at surgery, preoperative LAT talus-first metatarsal angle, change in LAT talus-first metatarsal angle, and degree of CC subluxation. Presence of a bony spur at the navicular bone was significantly associated with sex, diagnosis, age at surgery, and degree of CC subluxation (Table 5). 4. Discussion To our knowledge, this is the first study investigating the nature and risk factors of radiographic changes in the mid-tarsal joint after calcaneal lengthening in patients with planovalgus foot deformity. We found that 54.4% of feet showed radiographic osteoarthritis at the
mid-tarsal joint after calcaneal lengthening, and that these changes were associated with higher age at surgery, preoperative severity of the deformity, and degree of CC subluxation after surgery. There are some limitations to this study. First, the outcomes after calcaneal lengthening were assessed in terms of radiographic parameters and not clinical outcomes. While direct assessment of clinical outcomes is also important, it should be noted that radiographic outcomes reportedly correlate with clinical outcomes [26]. In addition, it is difficult to assess the clinical outcomes after calcaneal lengthening in patient with cerebral palsy because this procedure is usually performed as one of the single event multilevel surgery to improve gait pattern. Second, the number of patients included in this study was relatively small and the patients were not evaluated until skeletal maturity. Further study using a large cohort is required to investigate the long-term changes in the mid-tarsal joint after calcaneal lengthening osteotomy. Third, radiographic osteoarthritis is usually as changes with K–L grade 2 [21,27], while the current study defined radiographic osteoarthritis at the CC or TN joint as the modified K–L grade 1 or above. The majority of radiographic osteoarthritis at CC or TN joints in this study was Grade 1. We used the modified K–L grading system because, in our experience, it is difficult to discriminate between grade 0 and 1 in the original system. Therefore, it can be considered that grade 1 in the modified K–L system corresponds to grade 2 in the original K–L system. Fourth, this study had a retrospective design, and we did not use CT, but used plain radiograph to assess radiographic osteoarthritis. Further prospective study using CT to assess the change in the mid-tarsal joint after calcaneal lengthening is needed. Although the mid-tarsal joint is actually composed of two separate anatomical articulations, it is described as a single functional unit. The navicular and cuboid bones can be considered one rigid body because, although there is some relative motion between the two, these bones always move principally in the same direction [28]. Arthritis of the mid-tarsal joint frequently leads to significant problems in function, not only secondary to pain from inflammation and arthrosis but also as a result of altered kinematics of the foot [29]. Altered biomechanics involved in CC joint osteoarthritis are transferred to the tibiotalar joint, leading to tibiotalar osteoarthritis [20]. Therefore, we believe that it is clinically worthwhile to investigate the radiographic changes in the mid-tarsal joint after calcaneal lengthening. In our study, the degree of CC subluxation increased substantially after calcaneal lengthening, which is in accordance with previous observations [1,2,4,8,13]. Dorsal subluxation of the distal calcaneal fragment may occur during distraction of the osteotomy site, and degenerative changes at the CC joint may result from CC subluxation. Therefore, some authors recommended pinning of the CC joint before osteotomy distraction to prevent subluxation [4,13]. However, some authors found that pinning before graft positioning was ineffective in avoiding CC subluxation and that CC joint subluxation improved spontaneously over time [1,30]. Several studies investigating outcomes after calcaneal lengthening showed that postoperative CC subluxation did not increase the risk of arthrosis at the mid-tarsal joint and did not affect clinical outcome [1,13,15,30,31]. On the contrary, a previous study
Table 3 Changes in radiographic measurements after calcaneal lengthening in patients with planovalgus foot deformity. Parameters
Preoperative
1year postoperative
Mean difference
Final follow-up
AP talus-first metatarsal angle ( ) LAT talus-first metatarsal angle ( ) Calcaneal pitch angle ( ) Calcaneocuboid joint subluxation ( )
26.4 11.6 25.0 12.4 4.0 6.8 0.2 1.5
9.5 6.6 6.6 5.1 14.5 7.3 2.9 1.6
17.0 12.8 18.5 12.2 10.5 7.2 3.0 1.7
5.2 12.2 7.4 6.0 10.8 6.8 2.0 1.5
p-value Preop-1Y postop
Preop-final
1Y postop-final
RM-ANOVA
<0.001 <0.001 <0.001 <0.001
<0.001 <0.001 <0.001 <0.001
0.066 1.000 0.001 <0.001
<0.001 <0.001 <0.001 <0.001
RM-ANOVA, repeated measures analysis of variance.
Please cite this article in press as: K.H. Sung, et al., Radiographic changes of the mid-tarsal joint after calcaneal lengthening for planovalgus foot deformity, Foot Ankle Surg (2018), https://doi.org/10.1016/j.fas.2018.12.008
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Table 4 Incidence of radiographic osteoarthritic change at calcaneocuboid joint and talonavicular joint. Modified Kellgren–Lawrence grade Calcaneocuboid joint Talonavicular joint
0 37 (54%) 48 (71%)
1 25 (37%) 11 (16%)
Presence of bony spur Calcaneocuboid joint Talonavicular joint
Yes 5 (7%) 8 (12%)
No 63 (93%) 60 (88%)
2 6 (9%) 9 (13%)
3 0 0
4 0 0
N = 68 feet.
Table 5 Associated factors with radiographic osteoarthritic change at calcaneocuboid and talonavicular joint. Calcaneocuboid joint
Talonavicular joint
Adjusted ORs (95% CI)
P value
Adjusted ORs (95% CI)
P value
Demographic factor Sex (men) Follow up duration (year) Laterality (Rt.) Diagnosis (cerebral palsy) Age at operation (year)
0.5 (0.2–1.3) 1.2 (0.9–1.4) 1.4 (0.5–4.1) 1.7 (0.6–4.6) 1.2 (1.0–1.4)
0.159 0.156 0.526 0.333 0.038
0.3 (0.1–1.6) 1.2 (0.8–1.9) 1.0 (0.2–5.2) 0.3 (0.0–2.0) 2.2 (1.3–3.5)
0.152 0.366 0.958 0.206 0.002
Radiologic factor Preoperative lateral talus-1st metatarsal angle Change of lateral talus-1st metatarsal angle Degree of calcaneocuboid joint subluxation Preoperative AP talus-1st metatarsal angle Change of AP talus-1st metatarsal angle
1.0 1.0 1.3 1.0 1.0
0.208 0.548 0.217 0.973 0.813
1.0 (0.9–1.2) 0.9 (0.8–1.1) 2.1 (1.2–3.7) 1.1 (1.0–1.2) 1.0 (1.0–1.1)
0.877 0.410 0.007 0.044 0.217
(0.9–1.0) (0.8–1.1) (0.8–2.1) (0.9–1.1) (0.9–1.0)
Multivariate analysis using generalized estimation equation was used to calculate the ORs and 95% CI. OR, odds ratio; CI, confidence interval; AP, anteroposterior.
showed osteoarthritic changes at the CC and TN joint in 91.3% and 26.1% of patients, respectively, at a minimum follow-up of 7 years after non-stabilized calcaneal lengthening [14], which is in agreement with our present findings at a minimum follow-up of 5 years after calcaneal lengthening. In addition, it has been reported that 32% of feet showed degeneration at the subtalar joint and 24% at TN joint after lateral column lengthening in adult acquired flatfoot [32]. Calcaneal lengthening may generate excessive pressure, leading to CC joint arthrosis. However, evidence from cadaveric studies is not consistent regarding the pressure across the CC joint after calcaneal lengthening. Cooper et al. found that the compressive forces at the CC joint increased after 10-mm lengthening, [33] whereas Momberger et al. found no increase beyond physiologic loads in a cadaveric flatfoot model [8]. In another cadaveric study, Xia et al. found that calcaneal lengthening can decrease the abnormally high pressure across the CC joint in flatfoot, although lengthening >8 mm led to increased pressure in the CC joint [34]. Therefore, studies in a clinical setting are warranted to clarify the postoperative change in CC joint pressure following lengthening. After calcaneal lengthening, degenerative change can develop not only at the CC joint but also at the TN joint because the cuboid and navicular move as a single unit. In planovagus, TN subluxation is reduced and the medial portion of the talus at the TN joint, which is not part of the joint before surgery, becomes a functional part of the joint surface after calcaneal lengthening. Therefore, we believe that osteoarthritic change at the TN joint can occur postoperatively, as seen at the ankle joint after tendo-Achilles lengthening for longstanding equinus deformity [35]. We found that the risk of osteoarthritic change at the mid-tarsal joint was associated with higher age at surgery, degree of CC joint subluxation, and preoperative AP talus-first metatarsal angle, suggesting that prolonged duration of TN subluxation and high degrees of correction may be promote degenerative changes. Therefore, surgical correction of planovalgus deformity should not be delayed to prevent excessive correction and degenerative changes at the mid-tarsal joint.
5. Conclusions In conclusion, this study found that about half of the assessed feet show radiographic osteoarthritic changes at the mid-tarsal joint, including the CC and TN joints, after calcaneal lengthening for planovalgus foot deformity at a minimum follow-up of 5 years. In addition, increased age at surgery, preoperative severity of the deformity, and degree of CC joint subluxation after surgery were associated with radiographic osteoarthritic changes at the mid-tarsal joint. Therefore, surgeons should consider these factors in the surgical correction of planovalgus foot deformity to prevent mid-tarsal arthritis. Conflict of interest The authors declare that they have no conflict of interest. Acknowledgements This research was supported by Projects for Research and Development of Police science and Technology under Center for Research and Development of Police science and Technology and Korean National Police Agency funded by the Ministry of Science, ICT and Future Planning (Grant No. PA-C000001-2015-202), by the Bio & Medical Technology Development Program of the National Research Foundation (NRF) funded by the Ministry of Science & ICT (2017M3A9D8064200), and by SNUBH research fund (grant no. 122013-016). We thank Sung Jin Kim for radiographic measurements. References [1] Adams Jr. SB, Simpson AW, Pugh LI, Stasikelis PJ. Calcaneocuboid joint subluxation after calcaneal lengthening for planovalgus foot deformity in children with cerebral palsy. J Pediatr Orthop 2009;29:170–4. [2] Sung KH, Chung CY, Lee KM, Lee SY, Park MS. Calcaneal lengthening for planovalgus foot deformity in patients with cerebral palsy. Clin Orthop Relat Res 2013;471:1682–90.
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Foot and Ankle Surgery xxx (2018) xxx–xxx
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Radiographic changes of the mid-tarsal joint after calcaneal lengthening for planovalgus foot deformity Ki Hyuk Sunga,1, Soon-Sun Kwonb,1, Chin Youb Chunga , Kyoung Min Leea , Moon Seok Parka,* a Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, 82 Gumi-ro 173 Beon-gil, Bundang-Gu, Seongnam, Gyeonggi 13620, South Korea b Department of Mathematics, College of Natural Sciences, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon, Gyeonggi 16499, South Korea
A R T I C L E I N F O
A B S T R A C T
Article history: Received 16 October 2018 Received in revised form 16 November 2018 Accepted 21 December 2018 Available online xxx
Background: This study evaluate the radiographic changes in the mid-tarsal joint, including the calcaneocuboid and talonavicular (TN) joints after calcaneal lengthening for planovalgus deformity in children. Methods: This study included 38 patients (68 feet) who underwent calcaneal lengthening for planovalgus deformity. Radiographic osteoarthritic changes at the CC or TN joint were defined as modified Kellgren– Lawrence grade of 1. Results: Among the 68 feet, 31 feet (45.6%) showed radiographic osteoarthritic changes at the CC joint and 20 (29.4%) showed changes at the TN joint. Risk of radiographic osteoarthritic changes at the CC joint was associated with increased age at surgery (OR = 1.2, p = 0.038). Risk of radiographic osteoarthritic changes at the TN joint was associated with increased age at surgery (OR = 2.2; p = 0.002), preoperative AP talus-1st metatarsal angle (OR = 1.1; p = 0.044), and degree of CC subluxation (OR = 2.1; p = 0.007). Conclusions: Surgeons should consider the risk factors in the surgical correction of planovalgus deformity to prevent mid-tarsal arthritis. © 2018 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.
Keywords: Calcaneal lengthening Planovalgus deformity Mid-tarsal joint Radiographic osteoarthritic change
1. Introduction In children and adolescents, planovalgus foot deformity is characterized by complex features including hindfoot valgus, midfoot planus/pronation, and forefoot abduction/supination with a relatively short lateral column [1,2]. Most children with planovalgus deformities are asymptomatic and do not require treatment. When the deformity becomes symptomatic and leads to pain while weight-bearing, callus formation, or ulcerative lesions as a result of talar head prominence and functional impairment, it will require treatment [3,4]. Idiopathic planovalgus is known to improve spontaneously as children grow older [5], but surgical treatment is considered when the patient does not respond to conservative treatment [4,6,7]. Many surgical procedures such as arthrodesis, arthroereisis, lengthening of the lateral column, and calcaneal medial displacement osteotomy have been suggested [3,8]. Of these,
calcaneal lengthening is an effective surgical treatment for planovalgus foot deformity in children [4,6,7,9–12]. However, concerns have been raised in relation to calcaneocuboid (CC) joint subluxation and increased CC joint pressure after calcaneal lengthening [1,4,8,13], which may lead to degenerative arthritis of the CC joint [13,14]. The incidence of degenerative changes in the CC joint after calcaneal lengthening was reported at 0–91.3% [1,13–15]. However, most previous studies on calcaneal lengthening focused only on the CC joint and did not investigate long-term changes in the midtarsal joint, which includes the CC and talonavicular (TN) joints. Therefore, the present study aimed to evaluate the radiographic changes in the mid-tarsal joint including the CC and TN joints after calcaneal lengthening for planovalgus foot deformity in children, and to identify the risk factors for such changes. We hypothesized that a degenerative change at the mid-tarsal joint would develop after calcaneal lengthening. 2. Material and methods
* Corresponding author. E-mail addresses: [email protected] (K.H. Sung), [email protected] (S.-S. Kwon), [email protected] (C.Y. Chung), [email protected] (K.M. Lee), [email protected] (M.S. Park). 1 These authors contributed equally to the writing of this article.
This retrospective study was approved by the institutional review board at our institution. The need for informed consent was waived because of the retrospective design of the study.
https://doi.org/10.1016/j.fas.2018.12.008 1268-7731/© 2018 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.
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2.1. Patients
2.3. Consensus-building and radiographic parameters
Patients who underwent calcaneal lengthening for planovalgus deformity between May 2003 and January 2012 were enrolled in our study according to the following inclusion criteria: age <20 years; minimum follow-up of 5 years; availability of preoperative and postoperative anteroposterior (AP) and lateral (LAT) weightbearing foot radiographs. The exclusion criteria were as follows: concurrent medial column procedures such as medial cuneiform osteotomy, TN capsular plication, tibialis posterior tendon reefing, or TN fusion; foot radiographs inadequate for assessment. Data regarding the patients’ age at surgery, sex, diagnosis (cerebral palsy or idiopathic), affected side (right or left), and duration of followup were obtained by reviewing the medical records in our hospital’s database. Between May 2003 and January 2012, we performed 405 calcaneal lengthening operations in 231 patients with planovalgus deformity. Four patients (8 feet) were excluded due to lack of adequate foot radiographs and 189 patients (329 feet) were excluded due to inadequate follow-up duration (<5 years). Therefore, 38 patients (68 feet) were finally included in our study, and 204 AP and LAT standing foot radiographs were assessed. The etiology was cerebral palsy in 25 patients (44 feet) and idiopathic in 13 patients (24 feet). Among the patients with cerebral palsy, 19 underwent bilateral surgery and 6 underwent unilateral surgery. Among the patients with idiopathic etiology, 11 underwent bilateral surgery and 2 underwent unilateral surgery (Table 1).
Before the radiographic measurements, a consensus-building session to select and define suitable radiographic parameters was held by five orthopedic surgeons, who had an experience in orthopedic surgery (30, 17, 15, 13, and 7 years, respectively). Previous studies were reviewed, [2,11,12,16–18] and four parameters considered to have clinical relevance in quantifying planovalgus foot deformity were selected for the radiographic measurements. To assess the radiographic osteoarthritic changes in the CC and TN joints, the modified Kellgren–Lawrence (K–L) scoring system was used [19–21]. K–L grade has high intraobserver reliability [21]. The radiographic evaluation included weight-bearing AP and LAT foot radiographs obtained using a UT 2000 X-ray machine (Philips Research, Eindhoven, The Netherlands), with a source-toimage distance of approximately 100 cm. The X-ray machine settings were 46–50 kVp and 4.5–5 mA s, depending on patient body size. All conventional radiographic images were digitally acquired using picture archiving and communication software (INFINITT Healthcare, Seoul, Korea), which was subsequently used for measurements. On the LAT weight-bearing radiographs, calcaneal pitch angle, LAT talus-first metatarsal angle, and degree of CC subluxation were measured [2]. The calcaneal pitch angle was defined as the angle between a line drawn along the edge of the plantar soft tissue shadow and a line drawn along the lower margin of the calcaneus. The LAT talus-first metatarsal angle was defined as the angle between a line bisecting the long axis of the first metatarsal bone and a line drawn through the midpoints of the talar head and neck. The degree of CC subluxation was defined as the angle between a line drawn through the midpoint of the articular surface of the calcaneus and the most posterior aspect of the calcaneus, and a line drawn through the midpoint of the articular surface of the cuboid and the most posterior aspect of the calcaneus (Fig. 1). The modified K–L grade of the CC and TN joints was decided based on osteophyte formation and joint space narrowing compared to the first metatarsocuneiform joint (Table 2,Fig. 2). Osteophyte size was measured as the degree of protrusion from the anterior margin of the talus or calcaneus. The presence of a bony spur at the talus or calcaneus was also recorded. Radiographic osteoarthritic changes in the CC or TN joint were defined as the modified K–L grade 1 or above. On the AP weight-bearing radiographs, the AP talus-first metatarsal angle was measured as the angle between a line
2.2. Operative procedure Operative treatment was indicated for patients in whom conservative treatment failed and who had a significant deformity that was either painful or limited function. Calcaneal lengthening was performed by two pediatric orthopedic surgeons (CYC, MSP) who followed the same protocol. The surgical procedure used was a minor modification of the Evans technique [4]. Using an oscillating saw, transverse osteotomy was performed between the anterior and the middle facets of the calcaneus, 1.5 cm proximal to the CC joint. Under fluoroscopic guidance, the osteotomy surfaces of the proximal and distal calcaneal fragments were widened using a laminar spreader until anatomic reduction of the subtalar and TN joints was achieved. A commercially available human iliac crest allograft bone wedge was trimmed into a trapezoidal shape, sized to fit the osteotomy site, and inserted in the distracted area. Stabilization of the bone graft or CC joint was not performed. The peroneus brevis tendon was lengthened using Z-plasty, but the peroneus longus tendon was not lengthened. In patients with equinus deformity, concomitant tendo-Achilles lengthening or Strayer procedure was performed. After the surgery, the operated foot was immobilized with a short leg cast, and the non-weight bearing period was set at a minimum of 6 weeks. After radiographic union was confirmed, standing and weight-bearing were resumed with a leaf spring-type ankle-foot orthosis, which was worn for 3 months.
Table 1 Summary of patient demographics and clinical characteristics. Parameters
Values
Sex (male/female) Age at surgery (years) Follow-up duration (years) Laterality (bilateral/unilateral) Etiology (Cerebral palsy/idiopathic)
23/15 11 4 (range: 5–19) 8 3 (range: 5–13) 30/8 25/13
Fig. 1. Definition of radiographic parameters measured on lateral weight-bearing radiographs of the foot. The calcaneal pitch angle (CP) is defined as the angle between a line drawn along the edge of the plantar soft tissue shadow and a line drawn along the lower margin of the calcaneus. The lateral talus-first metatarsal angle (Lat talo-1MT) is defined as the angle between a line bisecting the long axis of the first metatarsal bone and a line drawn through the midpoints of the talar head and neck. Calcaneocuboid subluxation is defined as the angle between a line drawn through the midpoint of the articular surface of the calcaneus and the most posterior aspect of the calcaneus (A), and a line drawn through the midpoint of the articular surface of the cuboid and the most posterior aspect of the calcaneus (B).
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K.H. Sung et al. / Foot and Ankle Surgery xxx (2018) xxx–xxx Table 2 Grading Scales for the Radiographic Osteoarthritis Classification System of talonavicular and calcaneocuboid joint by Modified Kellgren–Lawrence grade19–21. Grade
0 1 2 3 4
Radiographic signs Osteophyte formation
Joint space narrowing
<1 mm 1–2 mm 2–4 mm 4–6 mm 6 mm
<25% 25–50% 50–75% 75% Obliteration
The modified Kellgren–Lawrence grade was determined based on either osteophyte formation or joint space narrowing when compared to the first metatarsocuneiform joint.
drawn through the midpoints of the talar head and neck, and a line bisecting the long axis of the first metatarsal bone (Fig. 3).
3
estimating equation (GEE) was employed for statistical analysis [25]. To identify the risk factors for long-term osteoarthritic changes following surgical treatment for planovalgus foot deformity, the associations between potential risk factors and the modified K–L grade at the CC and TN joints or the presence of a bony spur were assessed using GEE-based multivariate analysis to calculate the adjusted odds ratios (ORs) and 95% CIs. In the model, the patient age at surgery, sex, diagnosis, and radiographic parameters were treated as fixed effects, while the individual subjects and affected side were treated as random effects. While the working covariance structure could assume different types according to the model, we used compound symmetry covariance structure. Statistical analyses were conducted using R version 3.2.5 (R Foundation for Statistical Computing, Vienna, Austria). All tests were two-tailed, and p-values < 0.05 were considered to indicate significance.
2.4. Reliability testing and radiographic measurement 3. Results After consensus-building, reliability testing was conducted prior to performing the measurements included in our analysis. Two orthopedic surgeons (13 and 4 years of experience in orthopedic surgery, respectively) assessed the interobserver reliability of the radiographic measurements by independently measuring the radiographic parameters for 15 feet, while blinded to the patients’ clinical information and to the measurements reported by other examiners. After reliability testing for each radiographic parameter, all measurements on the preoperative, 1 year postoperative and final follow-up radiographs were performed by one orthopedic surgeon. 2.5. Statistical analysis The intraclass correlation coefficients (ICCs) and their 95% confidence intervals (CIs) were used to summarize the interobserver reliabilities of radiographic measurements, and were calculated in the setting of a two-way mixed-effect model, assuming a single measurement and absolute agreement [22,23]. With an ICC target value of 0.9, a Bonett approximation was used with 0.2 set as the width of the 95% CIs [24]. The minimum sample size required for detecting clinically meaningful differences was calculated to be 15 feet. Preoperative radiographic measurements were compared with values obtained at 1 year postoperatively and at final follow-up using repeated-measures analysis of variance (ANOVA) with a Bonferroni post-hoc test. To consider bilateral case, a generalized
All radiographic parameters showed excellent reliability (ICC, 0.911–0.980). AP talus-first metatarsal angle, LAT talus-first metatarsal angle, and calcaneal pitch angle improved significantly after surgery (all p < 0.001). While no further changes in AP talusfirst metatarsal angle or LAT talus-first metatarsal angle were noted at final follow-up (p = 0.066 and 1.000, respectively), calcaneal pitch angle decreased significantly between the 1-year follow-up and final follow-up (p = 0.001). Similarly, the degree of CC subluxation increased significantly after surgery (p < 0.001) but had decreased at final follow-up (p < 0.001) (Table 3). A bony spur was noted at the CC joint in 5 feet (7.4%) and at the TN joint in 8 feet (11.8%). Radiographic osteoarthritic changes were noted at the CC joint in 31 feet (45.6%; modified K–L grade: 1 in 25 feet, 2 in 6 feet) and at the TN joint in 20 feet (29.4%; (modified K–L grade: 1 in 11 feet, 2 in 9 feet). Nine feet (13.2%) had a bony spur at the CC or TN joint, and 37 feet (54.4%) showed radiographic osteoarthritic changes at the CC or TN joint (Table 4). The risk of radiographic osteoarthritic changes at the CC joint increased with age at surgery (OR, 1.2; 95% CI, 1.0–1.4; p = 0.038) but was not associated with sex, affected side, diagnosis, or radiographic parameters. The risk of radiographic osteoarthritis at the TN joint also increased with age at surgery (OR, 2.2; 95% CI,1.3–3.5; p = 0.002), but was furthermore significantly associated with preoperative AP talus-first metatarsal angle (OR, 1.1; 95% CI, 1.0–1.2; p = 0.044) and degree of CC subluxation (OR, 2.1; 95% CI, 1.2–3.7; p = 0.007). Presence of a bony spur at the calcaneus was significantly associated
Fig. 2. Modified Kellgren–Lawrence grade of the calcaneocuboid and talonavicular joints was decided based on osteophyte formation and joint space narrowing. Osteophyte size (A) was measured as the degree of protrusion from the anterior margin of the talus or calcaneus. Joint space narrowing of calcaneocuboid or talonavicualr joints (B) were compared to the width of first metatarsocuneiform joint (C).
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Fig. 3. Definition of radiographic parameters measured on anteroposterior weightbearing radiographs of the foot. The anteroposterior talus-first metatarsal angle is defined as the angle between a line drawn through the midpoints of the talar head and neck (A) and a line bisecting the long axis of the first metatarsal bone (B).
with sex, diagnosis, age at surgery, preoperative LAT talus-first metatarsal angle, change in LAT talus-first metatarsal angle, and degree of CC subluxation. Presence of a bony spur at the navicular bone was significantly associated with sex, diagnosis, age at surgery, and degree of CC subluxation (Table 5). 4. Discussion To our knowledge, this is the first study investigating the nature and risk factors of radiographic changes in the mid-tarsal joint after calcaneal lengthening in patients with planovalgus foot deformity. We found that 54.4% of feet showed radiographic osteoarthritis at the
mid-tarsal joint after calcaneal lengthening, and that these changes were associated with higher age at surgery, preoperative severity of the deformity, and degree of CC subluxation after surgery. There are some limitations to this study. First, the outcomes after calcaneal lengthening were assessed in terms of radiographic parameters and not clinical outcomes. While direct assessment of clinical outcomes is also important, it should be noted that radiographic outcomes reportedly correlate with clinical outcomes [26]. In addition, it is difficult to assess the clinical outcomes after calcaneal lengthening in patient with cerebral palsy because this procedure is usually performed as one of the single event multilevel surgery to improve gait pattern. Second, the number of patients included in this study was relatively small and the patients were not evaluated until skeletal maturity. Further study using a large cohort is required to investigate the long-term changes in the mid-tarsal joint after calcaneal lengthening osteotomy. Third, radiographic osteoarthritis is usually as changes with K–L grade 2 [21,27], while the current study defined radiographic osteoarthritis at the CC or TN joint as the modified K–L grade 1 or above. The majority of radiographic osteoarthritis at CC or TN joints in this study was Grade 1. We used the modified K–L grading system because, in our experience, it is difficult to discriminate between grade 0 and 1 in the original system. Therefore, it can be considered that grade 1 in the modified K–L system corresponds to grade 2 in the original K–L system. Fourth, this study had a retrospective design, and we did not use CT, but used plain radiograph to assess radiographic osteoarthritis. Further prospective study using CT to assess the change in the mid-tarsal joint after calcaneal lengthening is needed. Although the mid-tarsal joint is actually composed of two separate anatomical articulations, it is described as a single functional unit. The navicular and cuboid bones can be considered one rigid body because, although there is some relative motion between the two, these bones always move principally in the same direction [28]. Arthritis of the mid-tarsal joint frequently leads to significant problems in function, not only secondary to pain from inflammation and arthrosis but also as a result of altered kinematics of the foot [29]. Altered biomechanics involved in CC joint osteoarthritis are transferred to the tibiotalar joint, leading to tibiotalar osteoarthritis [20]. Therefore, we believe that it is clinically worthwhile to investigate the radiographic changes in the mid-tarsal joint after calcaneal lengthening. In our study, the degree of CC subluxation increased substantially after calcaneal lengthening, which is in accordance with previous observations [1,2,4,8,13]. Dorsal subluxation of the distal calcaneal fragment may occur during distraction of the osteotomy site, and degenerative changes at the CC joint may result from CC subluxation. Therefore, some authors recommended pinning of the CC joint before osteotomy distraction to prevent subluxation [4,13]. However, some authors found that pinning before graft positioning was ineffective in avoiding CC subluxation and that CC joint subluxation improved spontaneously over time [1,30]. Several studies investigating outcomes after calcaneal lengthening showed that postoperative CC subluxation did not increase the risk of arthrosis at the mid-tarsal joint and did not affect clinical outcome [1,13,15,30,31]. On the contrary, a previous study
Table 3 Changes in radiographic measurements after calcaneal lengthening in patients with planovalgus foot deformity. Parameters
Preoperative
1year postoperative
Mean difference
Final follow-up
AP talus-first metatarsal angle ( ) LAT talus-first metatarsal angle ( ) Calcaneal pitch angle ( ) Calcaneocuboid joint subluxation ( )
26.4 11.6 25.0 12.4 4.0 6.8 0.2 1.5
9.5 6.6 6.6 5.1 14.5 7.3 2.9 1.6
17.0 12.8 18.5 12.2 10.5 7.2 3.0 1.7
5.2 12.2 7.4 6.0 10.8 6.8 2.0 1.5
p-value Preop-1Y postop
Preop-final
1Y postop-final
RM-ANOVA
<0.001 <0.001 <0.001 <0.001
<0.001 <0.001 <0.001 <0.001
0.066 1.000 0.001 <0.001
<0.001 <0.001 <0.001 <0.001
RM-ANOVA, repeated measures analysis of variance.
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Table 4 Incidence of radiographic osteoarthritic change at calcaneocuboid joint and talonavicular joint. Modified Kellgren–Lawrence grade Calcaneocuboid joint Talonavicular joint
0 37 (54%) 48 (71%)
1 25 (37%) 11 (16%)
Presence of bony spur Calcaneocuboid joint Talonavicular joint
Yes 5 (7%) 8 (12%)
No 63 (93%) 60 (88%)
2 6 (9%) 9 (13%)
3 0 0
4 0 0
N = 68 feet.
Table 5 Associated factors with radiographic osteoarthritic change at calcaneocuboid and talonavicular joint. Calcaneocuboid joint
Talonavicular joint
Adjusted ORs (95% CI)
P value
Adjusted ORs (95% CI)
P value
Demographic factor Sex (men) Follow up duration (year) Laterality (Rt.) Diagnosis (cerebral palsy) Age at operation (year)
0.5 (0.2–1.3) 1.2 (0.9–1.4) 1.4 (0.5–4.1) 1.7 (0.6–4.6) 1.2 (1.0–1.4)
0.159 0.156 0.526 0.333 0.038
0.3 (0.1–1.6) 1.2 (0.8–1.9) 1.0 (0.2–5.2) 0.3 (0.0–2.0) 2.2 (1.3–3.5)
0.152 0.366 0.958 0.206 0.002
Radiologic factor Preoperative lateral talus-1st metatarsal angle Change of lateral talus-1st metatarsal angle Degree of calcaneocuboid joint subluxation Preoperative AP talus-1st metatarsal angle Change of AP talus-1st metatarsal angle
1.0 1.0 1.3 1.0 1.0
0.208 0.548 0.217 0.973 0.813
1.0 (0.9–1.2) 0.9 (0.8–1.1) 2.1 (1.2–3.7) 1.1 (1.0–1.2) 1.0 (1.0–1.1)
0.877 0.410 0.007 0.044 0.217
(0.9–1.0) (0.8–1.1) (0.8–2.1) (0.9–1.1) (0.9–1.0)
Multivariate analysis using generalized estimation equation was used to calculate the ORs and 95% CI. OR, odds ratio; CI, confidence interval; AP, anteroposterior.
showed osteoarthritic changes at the CC and TN joint in 91.3% and 26.1% of patients, respectively, at a minimum follow-up of 7 years after non-stabilized calcaneal lengthening [14], which is in agreement with our present findings at a minimum follow-up of 5 years after calcaneal lengthening. In addition, it has been reported that 32% of feet showed degeneration at the subtalar joint and 24% at TN joint after lateral column lengthening in adult acquired flatfoot [32]. Calcaneal lengthening may generate excessive pressure, leading to CC joint arthrosis. However, evidence from cadaveric studies is not consistent regarding the pressure across the CC joint after calcaneal lengthening. Cooper et al. found that the compressive forces at the CC joint increased after 10-mm lengthening, [33] whereas Momberger et al. found no increase beyond physiologic loads in a cadaveric flatfoot model [8]. In another cadaveric study, Xia et al. found that calcaneal lengthening can decrease the abnormally high pressure across the CC joint in flatfoot, although lengthening >8 mm led to increased pressure in the CC joint [34]. Therefore, studies in a clinical setting are warranted to clarify the postoperative change in CC joint pressure following lengthening. After calcaneal lengthening, degenerative change can develop not only at the CC joint but also at the TN joint because the cuboid and navicular move as a single unit. In planovagus, TN subluxation is reduced and the medial portion of the talus at the TN joint, which is not part of the joint before surgery, becomes a functional part of the joint surface after calcaneal lengthening. Therefore, we believe that osteoarthritic change at the TN joint can occur postoperatively, as seen at the ankle joint after tendo-Achilles lengthening for longstanding equinus deformity [35]. We found that the risk of osteoarthritic change at the mid-tarsal joint was associated with higher age at surgery, degree of CC joint subluxation, and preoperative AP talus-first metatarsal angle, suggesting that prolonged duration of TN subluxation and high degrees of correction may be promote degenerative changes. Therefore, surgical correction of planovalgus deformity should not be delayed to prevent excessive correction and degenerative changes at the mid-tarsal joint.
5. Conclusions In conclusion, this study found that about half of the assessed feet show radiographic osteoarthritic changes at the mid-tarsal joint, including the CC and TN joints, after calcaneal lengthening for planovalgus foot deformity at a minimum follow-up of 5 years. In addition, increased age at surgery, preoperative severity of the deformity, and degree of CC joint subluxation after surgery were associated with radiographic osteoarthritic changes at the mid-tarsal joint. Therefore, surgeons should consider these factors in the surgical correction of planovalgus foot deformity to prevent mid-tarsal arthritis. Conflict of interest The authors declare that they have no conflict of interest. Acknowledgements This research was supported by Projects for Research and Development of Police science and Technology under Center for Research and Development of Police science and Technology and Korean National Police Agency funded by the Ministry of Science, ICT and Future Planning (Grant No. PA-C000001-2015-202), by the Bio & Medical Technology Development Program of the National Research Foundation (NRF) funded by the Ministry of Science & ICT (2017M3A9D8064200), and by SNUBH research fund (grant no. 122013-016). We thank Sung Jin Kim for radiographic measurements. References [1] Adams Jr. SB, Simpson AW, Pugh LI, Stasikelis PJ. Calcaneocuboid joint subluxation after calcaneal lengthening for planovalgus foot deformity in children with cerebral palsy. J Pediatr Orthop 2009;29:170–4. [2] Sung KH, Chung CY, Lee KM, Lee SY, Park MS. Calcaneal lengthening for planovalgus foot deformity in patients with cerebral palsy. Clin Orthop Relat Res 2013;471:1682–90.
Please cite this article in press as: K.H. Sung, et al., Radiographic changes of the mid-tarsal joint after calcaneal lengthening for planovalgus foot deformity, Foot Ankle Surg (2018), https://doi.org/10.1016/j.fas.2018.12.008
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Please cite this article in press as: K.H. Sung, et al., Radiographic changes of the mid-tarsal joint after calcaneal lengthening for planovalgus foot deformity, Foot Ankle Surg (2018), https://doi.org/10.1016/j.fas.2018.12.008