- Email: [email protected]
Lateral hinge fracture delays healing of the osteotomy gap in opening wedge high tibial osteotomy with a beta-tricalcium phosphate block
THEKNE-02936; No of Pages 6 The Knee xxx (xxxx) xxx
Contents lists available at ScienceDirect
The Knee
Lateral hinge fracture delays healing of the osteotomy gap in opening wedge high tibial osteotomy with a beta-tricalcium phosphate block Ken Kumagai ⁎, Shunsuke Yamada, Shuntaro Nejima, Shuntaro Muramatsu, Yasushi Akamatsu, Yutaka Inaba Department of Orthopaedic Surgery, Yokohama City University Hospital, Yokohama, Japan
a r t i c l e
i n f o
Article history: Received 28 July 2019 Received in revised form 2 October 2019 Accepted 28 October 2019 Available online xxxx Keywords: Opening wedge high tibial osteotomy Synthetic bone grafting Lateral hinge fracture Bone healing
a b s t r a c t Background: The purpose of this study was to investigate the healing process of synthetic bone grafts in opening wedge high tibial osteotomy (OWHTO) and to identify the factors that affect bone healing in OWHTO. It was hypothesized that lateral hinge fracture (LHF) is associated with delayed bone healing after OWHTO with synthetic bone grafting. Methods: The subjects included 350 knees of 283 patients who underwent OWHTO using two wedged blocks of beta-tricalcium phosphate (β-TCP) with 60% porosity. The healing of the osteotomy gap using a radiologic rating system for OWHTO with synthetic bone grafts and the presence of an LHF were assessed up to postoperative 24 months. Results: LHFs were found in 49 knees (14%). The osteotomy gap showed slower progression of radiographic healing with an LHF than without an LHF (P b .05). In the knees with LHFs, initial radiographic change in the osteotomy gap was observed almost at the same time as healing of the LHF. Multivariate logistic regression analysis identified LHF as the factor preventing the progression of bone healing (OR = 46.78, P b .05). Conclusions: LHF is associated with delayed bone healing after OWHTO with synthetic bone grafting. © 2019 Elsevier B.V. All rights reserved.
1. Introduction High tibial osteotomy (HTO) is an established procedure to correct lower limb alignment and to reduce mechanical force on the affected compartment. Proper overcorrection provides pain relief and subsequent improvement of knee function [1,2]. The opening wedge HTO (OWHTO) has recently been commonly used, and good mid- to long-term clinical outcomes have been demonstrated [3]. The opening gap is created in the OWHTO, and is filled with a variety of materials, such as autologous bone grafting, allogenic bone grafting, synthetic bone grafting, and often with no bone grafting. [4–6]. Various synthetic bone substitutes have been introduced to fill the opening gap instead of an autograft, with the advantage of avoiding donor-site morbidity [7–9]. A porous beta-tricalcium phosphate (β-TCP) is widely used as a bone graft material due to good biocompatibility, absorbability, and osteoconductivity [10,11]. As a disadvantage, the β-TCP shows less rapid progression of the bone remodeling process than osseous graft materials [12,13]. Some studies showed that the autograft was superior to the synthetic graft in terms of bone union [5,6], but others showed a similar tendency for radiological union and correction maintenance regardless of the type of bone [4]. A lateral hinge fracture (LHF) occurs as a complication in OWHTO [14], and it affects healing of the osteotomy gap with no bone graft [15,16]. It could be expected that an LHF also affects the remodeling speed of the bone graft in the osteotomy gap. ⁎ Corresponding author at: Department of Orthopaedic Surgery, Graduate School of Medicine, Yokohama City University Hospital, 3-9 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan. E-mail address: [email protected]. (K. Kumagai).
https://doi.org/10.1016/j.knee.2019.10.027 0968-0160/© 2019 Elsevier B.V. All rights reserved.
Please cite this article as: K. Kumagai, S. Yamada, S. Nejima, et al., Lateral hinge fracture delays healing of the osteotomy gap in opening wedge high tibial osteotomy wi..., The Knee, https://doi.org/10.1016/j.knee.2019.10.027
2
K. Kumagai et al. / The Knee xxx (xxxx) xxx
However, to date, it is not known whether an LHF contributes to the progression of bone healing with resorption and remodeling of the synthetic bone graft after OWHTO. The purpose of this study was to investigate LHFs and the healing process of the synthetic bone graft in OWHTO, and to identify the factors affecting bone healing in OWHTO. It was hypothesized that the presence of an LHF is associated with delayed bone healing after OWHTO using a synthetic bone graft.
2. Materials and methods A total of 384 consecutive knees of 312 patients underwent OWHTO between 2008 and 2015. Of these cases, 350 knees of 283 patients were followed-up postoperatively for at least two years, were available for review without missing data, and were retained as part of this study (follow-up rate 91%). Inclusion criteria were painful osteoarthritis or osteonecrosis localized to the medial compartment of the knee. Exclusion criteria were patients with severe varus deformity (over five degrees of anatomical varus alignment), flexion contracture greater than 15°, or a history of inflammatory arthritis, joint infection, or immunosuppressive therapy. Demographic data are shown in Table 1. This retrospective case series study was approved by the institutional review board at Yokohama City University (#B180200061).
2.1. Surgical procedure and postoperative management HTO was performed using biplanar opening-wedge technique with rigid plate fixation. The amount of angular correction was planned preoperatively aiming to achieve tibiofemoral anatomical valgus of 10° in a one-leg standing radiograph postoperatively. The osteotomy gap was filled with two wedged blocks of β-TCP with 60% porosity (Osferion®, Olympus Terumo Biomaterials. Corp., Tokyo, Japan) and fixed with TomoFix (DePuy Synthes, Zuchwil, Switzerland). Patients started a postoperative rehabilitation program including isometric quadriceps and range-of-motion exercises the day after surgery. A non-weight-bearing regimen was prescribed for one week, followed by partial weight-bearing exercise. Full weight-bearing exercise was permitted two weeks postoperatively. Casts or supportive devices were never applied.
2.2. Radiographic assessment For radiographic assessment, an anteroposterior weight-bearing radiograph of the knee was taken at postoperative one, three, six, 12, 18, and 24 months. The presence of an LHF was assessed using the classification previously described by Takeuchi et al. [14]. Limb alignment is expressed as the femorotibial angle (FTA), defined as the lateral angle between the femoral tibial axes [2]. Bone healing with resorption and remodeling of the β-TCP wedged blocks was assessed using the radiologic rating system previously described by van Hemert et al. [17] (Table 2). Delayed bone healing was defined as no radiologic change to phase 2 or greater at postoperative three months.
2.3. Statistical analysis Statistical analysis was carried out using BellCurve for Excel version 2.21 (Social Survey Research Information, Tokyo, Japan). Pearson's chi-squared tests were used to test for significant differences with respect to distribution in the phase classification of bone healing. Multivariate logistic regression was used to identify risk factors for delayed bone healing. An adjusted p value b.05 was considered significant. A power calculation indicated that a sample size of 324 could detect a difference in progression of bone healing with an effect size of 0.2, 5% probability of a type I error and power of 80%. The intra- and inter-rater reliabilities of radiographic evaluation were assessed by calculating intraclass correlation coefficients.
Table 1 Demographic data. Number of patients (knees) Male Female Age (years) Body mass index (kg/m2) Size of opening gap (mm) Preop. FTA (degrees) Postop. FTA (degrees)
283 (350) 87 (109) 196 (241) 65.8 ± 8.9 25.2 ± 3.9 13.1 ± 2.8 181.9 ± 2.5 169.7 ± 2.8
FTA, femorotibial angle.
Please cite this article as: K. Kumagai, S. Yamada, S. Nejima, et al., Lateral hinge fracture delays healing of the osteotomy gap in opening wedge high tibial osteotomy wi..., The Knee, https://doi.org/10.1016/j.knee.2019.10.027
K. Kumagai et al. / The Knee xxx (xxxx) xxx
3
Table 2 Phase classification of radiographic bone healing after opening wedge high tibial osteotomy by van Hemert [17]. Phase
Explanation
1 2 3 4 5
Osteopenic bone, rounded osteotomy sites, clear distinction between β-TCP and bone Whitening of sites and blurred distinction between β-TCP and bone Distinction between β-TCP and bone slightly visible, though healed osteotomy Full reformation, though osteotomy recognizable, no β-TCP No sign of osteotomy
Vascular phase Calcification phase Osteoblastic phase Consolidation phase Full remodeling
3. Results 3.1. Incidence of LHF LHFs were found in 49 knees (14%). Of these fractures, a type I fracture was observed in 39 knees, a type II fracture in four knees, and a type III fracture in six knees, according to Takeuchi's classification [14]. Breakage of the fixation plate occurred in one case with type I fracture, and revision surgery was performed two months after the initial surgery (this case was excluded from the analysis). Except for this case, fracture healing was confirmed without additional surgical treatment in all cases. There was no significant difference in the size of the opening gap between the group with LHFs (13.7 ± 3.0 mm) and the group without LHFs (13.0 ± 2.7 mm) (P = .112).
3.2. Radiographic assessments of bone healing Assessments of bone healing using the radiologic rating system described by van Hemert [17] are summarized with or without LHFs in Table 3. A significant difference was found in the progression of the bone healing phase at each time point. The ratio of phase 2 was lower in the knees with LHFs than in those without LHFs at postoperative three months. Similarly, the ratio of phase 3 was lower in the knees with LHFs than in those without LHFs at postoperative six and 12 months. Overall, the osteotomy gap showed slower progression of radiographic healing with an LHF than without an LHF. In the knees with LHFs, progression to phase 2 was observed almost at the same time as healing of the LHF (Figure 1). Representative cases with or without LHFs showing progression of radiographic bone healing are in Figure 2. The inter-rater reliability for assessment of bone healing according to the radiologic rating system of van Hemert was substantial, with a kappa value of 0.78 (0.74–0.82). The intra-rater reliability at more than two-month intervals was almost perfect, with a kappa value of 0.89 (0.86–0.91).
3.3. Factors affecting progression of bone remodeling The results of multivariate logistic regression analysis for factors affecting progression of bone healing are summarized in Table 4. The rate of LHF was significantly higher in knees with delayed bone healing. LHF was the only factor preventing the progression of bone healing. Age, sex, body mass index (BMI), size of the opening gap, and postoperative FTA did not affect progression of bone healing.
Table 3 Radiographic classification of bone healing phase in ostotomy gap with or without LHF. Time
1 month
Fracture Phase
1
3 months
6 months
12 months
(+)
(−)
(+)
(−)
(+)
(−)
(+)
49 (100%)
272 (90%) 29 (10%)
38 (78%) 11 (22%)
26 (9%) 272 (91%) 3 (1%)
9 (18%) 38 (78%) 2 (4%)
1 (0.3%) 225 (75%) 75 (25%)
2 (4%) 31 (63%) 16 (33%)
2 3 4
18 months
24 months
(−)
(+)
(−)
(+)
72 (24%) 228 (76%) 1 (0.3%)
18 (37%) 30 (61%) 1 (2%)
21 (7%) 269 (89%) 11 (4%)
7 10 (14%) (3%) 38 242 (78%) (80%) 3 45 (6%) (15%) 1 4 (2%) (1%) 0.0046
5 P value
0.0233
b0.001
b0.001
b0.001
b0.001
(−)
The values are given as the number of knees with the percentage in parentheses. LHF, lateral hinge fracture.
Please cite this article as: K. Kumagai, S. Yamada, S. Nejima, et al., Lateral hinge fracture delays healing of the osteotomy gap in opening wedge high tibial osteotomy wi..., The Knee, https://doi.org/10.1016/j.knee.2019.10.027
4
K. Kumagai et al. / The Knee xxx (xxxx) xxx
Figure 1. Rate of phase 2 reached osteotomy gap and healing of lateral hinge fracture (LHF).
4. Discussion The most important finding of the present study was that LHFs affected the progression of radiographic bone healing in the osteotomy gap after OWHTO using a synthetic bone graft. LHF was the only factor that delayed the healing of the osteotomy gap, whereas age, sex, BMI, size of the opening gap, and postoperative FTA did not affect it. These results support our hypothesis that LHF is associated with delayed bone healing after OWHTO with synthetic bone grafting. The role of bone grafting for the opening gap is still controversial. Several systematic reviews and meta-analyses found no definitive advantages with the use of any bone grafts in terms of union rates and loss of correction [4–6]. However, a large opening gap without bone grafting delays filling of the opening gap [15,18]. Furthermore, with respect to biomechanical properties, a synthetic bone graft for OWHTO provides additional initial stability [19] and has the potential to allow early full weight-bearing in combination with rigid plate fixation [3]. In addition to the biomechanical issues, biocompatibility, absorbability, and osteoconductivity are important properties in the synthetic bone graft. Since these properties depend on the kind of materials, as well as the shape, porosity, etc., the progression of bone healing differs among the previous reports [8,11,12,20,21]. The βTCP wedged blocks with 60% porosity that were used as a synthetic bone substitute in the present study showed a slow process
Figure 2. Progression of bone healing in the osteotomy gap with or without a lateral hinge fracture (LHF). The radiographs of the osteotomy gap without LHF show phase 1 at 1 month, phase 2 at 3 months, phase 3 at 6, 12, and 18 months, and phase 4 at 24 months (left panels). The radiographs of the osteotomy gap with LHF show phase 1 at 1 and 3 months, phase 2 at 6 months, and phase 3 at 12, 18, and 24 months (right panels). Arrowheads indicate LHF. Union of LHF is observed at 6 months, and thereafter the osteotomy gap shows progression of bone healing.
Please cite this article as: K. Kumagai, S. Yamada, S. Nejima, et al., Lateral hinge fracture delays healing of the osteotomy gap in opening wedge high tibial osteotomy wi..., The Knee, https://doi.org/10.1016/j.knee.2019.10.027
K. Kumagai et al. / The Knee xxx (xxxx) xxx
5
Table 4 Multivariate logistic regression of factors affecting delayed bone healing. Factors
Age (years) Sex (male, %) Body mass index (kg/m2) Size of opening gap (mm) Postoperative FTA (degrees) LHF (%)
Normal healing
Delayed healing
(n = 286)
(n = 64)
65.9 ± 8.7 30.4 25.3 ± 3.9 12.9 ± 2.7 169.9 ± 2.8 3.8
65.4 ± 9.9 34.3 25.2 ± 4.0 14.1 ± 3.1 169.2 ± 2.7 59.4
Odds Ratio
95% confidence interval
P value
0.974 1.212 0.813 1.152 0.906 46.784
0.930–1.021 0.399–3.682 0.529–1.247 0.967–1.372 0.792–1.038 19.126–114.441
0.271 0.735 0.343 0.113 0.154 b0.001
FTA, femorotibial angle. LHF, lateral hinge fracture.
of bone healing in comparison with the other reports using β-TCP with different porosity and shapes [13,17,22]. This study demonstrated further delay of bone healing in the osteotomy gap of the knees with LHFs. The lateral cortical hinge contributes to primary stability at the osteotomy site, and disruption of the lateral cortex brings about instability leading to delayed bone healing at the osteotomy site [23]. Unstable LHFs are associated with a particularly high risk of delayed bone healing [15,16], although bone union also depends on other factors such as smoking, BMI, fixation device, etc. [24–26]. Bone formation after OWHTO progressed from the lateral hinge to the medial direction with or without bone grafting [15,27]. The present study demonstrated that progression to phase 2 was associated with the timing of fracture healing. Namely, the initial response to the bone substitute does not appear to occur without fracture healing in cases with LHFs. The incidence of LHF associated with OWHTO varies widely in the literature (0–50%) [8,14,16,24,28,29], implying that it is one of the frequent complications with this procedure. To avoid delayed healing of the osteotomy site with synthetic bone substitutes, care must be taken not to break the lateral cortical hinge in OWHTO. In cases of LHF, it is likely that early fracture healing is important to avoid delayed union at the osteotomy site. This study has several limitations. First, the follow-up time of two years was not very long. The current series assessed the early phase of bone healing, and most cases did not achieve complete remodeling. Second, the present series included no younger population. This may contribute to the results that age was not correlated with progression of bone healing. Third, only anteroposterior radiographs were used for assessment of bone healing. 5. Conclusion LHF is associated with delayed bone healing after OWHTO with synthetic bone grafting. Source of funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Declaration of competing interest The authors declare that they have no conflict of interest. References [1] Coventry MB, Ilstrup DM, Wallrichs SL. Proximal tibial osteotomy. A critical long-term study of eighty-seven cases. J Bone Joint Surg Am 1993;75:196–201. [2] Koshino T, Yoshida T, Ara Y, Saito I, Saito T. Fifteen to twenty-eight years' follow-up results of high tibial valgus osteotomy for osteoarthritic knee. Knee 2004;11: 439–44. [3] Saito T, Kumagai K, Akamatsu Y, Kobayashi H, Kusayama Y. Five- to ten-year outcome following medial opening-wedge high tibial osteotomy with rigid plate fixation in combination with an artificial bone substitute. Bone Joint J 2014;96-B:339–44. [4] Han JH, Kim HJ, Song JG, Yang JH, Bhandare NN, Fernandez AR, et al. Is bone grafting necessary in opening wedge high tibial osteotomy? A meta-analysis of radiological outcomes. Knee Surg Relat Res 2015;27:207–20. [5] Lash NJ, Feller JA, Batty LM, Wasiak J, Richmond AK. Bone grafts and bone substitutes for opening-wedge osteotomies of the knee: a systematic review. Arthroscopy 2015;31:720–30. [6] Slevin O, Ayeni OR, Hinterwimmer S, Tischer T, Feucht MJ, Hirschmann MT. The role of bone void fillers in medial opening wedge high tibial osteotomy: a systematic review. Knee Surg Sports Traumatol Arthrosc 2016;24:3584–98. [7] Koshino T, Murase T, Saito T. Medial opening-wedge high tibial osteotomy with use of porous hydroxyapatite to treat medial compartment osteoarthritis of the knee. J Bone Joint Surg Am 2003;85-A:78–85. [8] Ozalay M, Sahin O, Akpinar S, Ozkoc G, Cinar M, Cesur N. Remodeling potentials of biphasic calcium phosphate granules in open wedge high tibial osteotomy. Arch Orthop Trauma Surg 2009;129:747–52. [9] Tanaka T, Kumagae Y, Saito M, Chazono M, Komaki H, Kikuchi T, et al. Bone formation and resorption in patients after implantation of beta-tricalcium phosphate blocks with 60% and 75% porosity in opening-wedge high tibial osteotomy. J Biomed Mater Res B Appl Biomater 2008;86:453–9. [10] Gaasbeek RD, Toonen HG, van Heerwaarden RJ, Buma P. Mechanism of bone incorporation of beta-TCP bone substitute in open wedge tibial osteotomy in patients. Biomaterials 2005;26:6713–9. [11] Onodera J, Kondo E, Omizu N, Ueda D, Yagi T, Yasuda K. Beta-tricalcium phosphate shows superior absorption rate and osteoconductivity compared to hydroxyapatite in open-wedge high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 2014;22:2763–70.
Please cite this article as: K. Kumagai, S. Yamada, S. Nejima, et al., Lateral hinge fracture delays healing of the osteotomy gap in opening wedge high tibial osteotomy wi..., The Knee, https://doi.org/10.1016/j.knee.2019.10.027
6
K. Kumagai et al. / The Knee xxx (xxxx) xxx
[12] Jung KA, Lee SC, Ahn NK, Hwang SH, Nam CH. Radiographic healing with hemispherical allogeneic femoral head bone grafting for opening-wedge high tibial osteotomy. Arthroscopy 2010;26:1617–24. [13] Kraal T, Mullender M, de Bruine JH, Reinhard R, de Gast A, Kuik DJ, et al. Resorbability of rigid beta-tricalcium phosphate wedges in open-wedge high tibial osteotomy: a retrospective radiological study. Knee 2008;15:201–5. [14] Takeuchi R, Ishikawa H, Kumagai K, Yamaguchi Y, Chiba N, Akamatsu Y, et al. Fractures around the lateral cortical hinge after a medial opening-wedge high tibial osteotomy: a new classification of lateral hinge fracture. Arthroscopy 2012;28:85–94. [15] Goshima K, Sawaguchi T, Shigemoto K, Iwai S, Nakanishi A, Inoue D, et al. Large opening gaps, unstable hinge fractures, and osteotomy line below the safe zone cause delayed bone healing after open-wedge high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 2019;27:1291–8. [16] Schroter S, Freude T, Kopp MM, Konstantinidis L, Dobele S, Stockle U, et al. Smoking and unstable hinge fractures cause delayed gap filling irrespective of early weight bearing after open wedge osteotomy. Arthroscopy 2015;31:254–65. [17] van Hemert WL, Willems K, Anderson PG, van Heerwaarden RJ, Wymenga AB. Tricalcium phosphate granules or rigid wedge preforms in open wedge high tibial osteotomy: a radiological study with a new evaluation system. Knee 2004;11:451–6. [18] El-Assal MA, Khalifa YE, Abdel-Hamid MM, Said HG, Bakr HM. Opening-wedge high tibial osteotomy without bone graft. Knee Surg Sports Traumatol Arthrosc 2010;18:961–6. [19] Takeuchi R, Bito H, Akamatsu Y, Shiraishi T, Morishita S, Koshino T, et al. In vitro stability of open wedge high tibial osteotomy with synthetic bone graft. Knee 2010;17:217–20. [20] Lee DY, Lee MC, Ha CW, Kyung HS, Kim CW, Chang MJ, et al. Comparable bone union progression after opening wedge high tibial osteotomy using allogenous bone chip or tri-calcium phosphate granule: a prospective randomized controlled trial. Knee Surg Sports Traumatol Arthrosc 2019;27:2945–50. [21] Oh KJ, Ko YB, Jaiswal S, Whang IC. Comparison of osteoconductivity and absorbability of beta-tricalcium phosphate and hydroxyapatite in clinical scenario of opening wedge high tibial osteotomy. J Mater Sci Mater Med 2016;27:179. [22] Tanaka T, Kumagae Y, Chazono M, Kitasato S, Kakuta A, Marumo K. A novel evaluation system to monitor bone formation and beta-tricalcium phosphate resorption in opening wedge high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 2015;23:2007–11. [23] Miller BS, Dorsey WO, Bryant CR, Austin JC. The effect of lateral cortex disruption and repair on the stability of the medial opening wedge high tibial osteotomy. Am J Sports Med 2005;33:1552–7. [24] Dexel J, Fritzsche H, Beyer F, Harman MK, Lutzner J. Open-wedge high tibial osteotomy: incidence of lateral cortex fractures and influence of fixation device on osteotomy healing. Knee Surg Sports Traumatol Arthrosc 2017;25:832–7. [25] Meidinger G, Imhoff AB, Paul J, Kirchhoff C, Sauerschnig M, Hinterwimmer S. May smokers and overweight patients be treated with a medial open-wedge HTO? Risk factors for non-union. Knee Surg Sports Traumatol Arthrosc 2011;19:333–9. [26] Siboni R, Beaufils P, Boisrenoult P, Steltzlen C, Pujol N. Opening-wedge high tibial osteotomy without bone grafting in severe varus osteoarthritic knee. Rate and risk factors of non-union in 41 cases. Orthop Traumatol Surg Res 2018;104:473–6. [27] Kobayashi H, Akamatsu Y, Kumagai K, Kusayama Y, Saito T. Radiographic and computed tomographic evaluation of bone union after medial opening wedge high tibial osteotomy with filling gap. Knee 2017;24:1108–17. [28] Lee SS, Celik H, Lee DH. Predictive factors for and detection of lateral hinge fractures following open wedge high tibial osteotomy: plain radiography versus computed tomography. Arthroscopy 2018;34:3073–9. [29] van Houten AH, Heesterbeek PJ, van Heerwaarden RJ, van Tienen TG, Wymenga AB. Medial open wedge high tibial osteotomy: can delayed or nonunion be predicted? Clin Orthop Relat Res 2014;472:1217–23.
Please cite this article as: K. Kumagai, S. Yamada, S. Nejima, et al., Lateral hinge fracture delays healing of the osteotomy gap in opening wedge high tibial osteotomy wi..., The Knee, https://doi.org/10.1016/j.knee.2019.10.027
Contents lists available at ScienceDirect
The Knee
Lateral hinge fracture delays healing of the osteotomy gap in opening wedge high tibial osteotomy with a beta-tricalcium phosphate block Ken Kumagai ⁎, Shunsuke Yamada, Shuntaro Nejima, Shuntaro Muramatsu, Yasushi Akamatsu, Yutaka Inaba Department of Orthopaedic Surgery, Yokohama City University Hospital, Yokohama, Japan
a r t i c l e
i n f o
Article history: Received 28 July 2019 Received in revised form 2 October 2019 Accepted 28 October 2019 Available online xxxx Keywords: Opening wedge high tibial osteotomy Synthetic bone grafting Lateral hinge fracture Bone healing
a b s t r a c t Background: The purpose of this study was to investigate the healing process of synthetic bone grafts in opening wedge high tibial osteotomy (OWHTO) and to identify the factors that affect bone healing in OWHTO. It was hypothesized that lateral hinge fracture (LHF) is associated with delayed bone healing after OWHTO with synthetic bone grafting. Methods: The subjects included 350 knees of 283 patients who underwent OWHTO using two wedged blocks of beta-tricalcium phosphate (β-TCP) with 60% porosity. The healing of the osteotomy gap using a radiologic rating system for OWHTO with synthetic bone grafts and the presence of an LHF were assessed up to postoperative 24 months. Results: LHFs were found in 49 knees (14%). The osteotomy gap showed slower progression of radiographic healing with an LHF than without an LHF (P b .05). In the knees with LHFs, initial radiographic change in the osteotomy gap was observed almost at the same time as healing of the LHF. Multivariate logistic regression analysis identified LHF as the factor preventing the progression of bone healing (OR = 46.78, P b .05). Conclusions: LHF is associated with delayed bone healing after OWHTO with synthetic bone grafting. © 2019 Elsevier B.V. All rights reserved.
1. Introduction High tibial osteotomy (HTO) is an established procedure to correct lower limb alignment and to reduce mechanical force on the affected compartment. Proper overcorrection provides pain relief and subsequent improvement of knee function [1,2]. The opening wedge HTO (OWHTO) has recently been commonly used, and good mid- to long-term clinical outcomes have been demonstrated [3]. The opening gap is created in the OWHTO, and is filled with a variety of materials, such as autologous bone grafting, allogenic bone grafting, synthetic bone grafting, and often with no bone grafting. [4–6]. Various synthetic bone substitutes have been introduced to fill the opening gap instead of an autograft, with the advantage of avoiding donor-site morbidity [7–9]. A porous beta-tricalcium phosphate (β-TCP) is widely used as a bone graft material due to good biocompatibility, absorbability, and osteoconductivity [10,11]. As a disadvantage, the β-TCP shows less rapid progression of the bone remodeling process than osseous graft materials [12,13]. Some studies showed that the autograft was superior to the synthetic graft in terms of bone union [5,6], but others showed a similar tendency for radiological union and correction maintenance regardless of the type of bone [4]. A lateral hinge fracture (LHF) occurs as a complication in OWHTO [14], and it affects healing of the osteotomy gap with no bone graft [15,16]. It could be expected that an LHF also affects the remodeling speed of the bone graft in the osteotomy gap. ⁎ Corresponding author at: Department of Orthopaedic Surgery, Graduate School of Medicine, Yokohama City University Hospital, 3-9 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan. E-mail address: [email protected]. (K. Kumagai).
https://doi.org/10.1016/j.knee.2019.10.027 0968-0160/© 2019 Elsevier B.V. All rights reserved.
Please cite this article as: K. Kumagai, S. Yamada, S. Nejima, et al., Lateral hinge fracture delays healing of the osteotomy gap in opening wedge high tibial osteotomy wi..., The Knee, https://doi.org/10.1016/j.knee.2019.10.027
2
K. Kumagai et al. / The Knee xxx (xxxx) xxx
However, to date, it is not known whether an LHF contributes to the progression of bone healing with resorption and remodeling of the synthetic bone graft after OWHTO. The purpose of this study was to investigate LHFs and the healing process of the synthetic bone graft in OWHTO, and to identify the factors affecting bone healing in OWHTO. It was hypothesized that the presence of an LHF is associated with delayed bone healing after OWHTO using a synthetic bone graft.
2. Materials and methods A total of 384 consecutive knees of 312 patients underwent OWHTO between 2008 and 2015. Of these cases, 350 knees of 283 patients were followed-up postoperatively for at least two years, were available for review without missing data, and were retained as part of this study (follow-up rate 91%). Inclusion criteria were painful osteoarthritis or osteonecrosis localized to the medial compartment of the knee. Exclusion criteria were patients with severe varus deformity (over five degrees of anatomical varus alignment), flexion contracture greater than 15°, or a history of inflammatory arthritis, joint infection, or immunosuppressive therapy. Demographic data are shown in Table 1. This retrospective case series study was approved by the institutional review board at Yokohama City University (#B180200061).
2.1. Surgical procedure and postoperative management HTO was performed using biplanar opening-wedge technique with rigid plate fixation. The amount of angular correction was planned preoperatively aiming to achieve tibiofemoral anatomical valgus of 10° in a one-leg standing radiograph postoperatively. The osteotomy gap was filled with two wedged blocks of β-TCP with 60% porosity (Osferion®, Olympus Terumo Biomaterials. Corp., Tokyo, Japan) and fixed with TomoFix (DePuy Synthes, Zuchwil, Switzerland). Patients started a postoperative rehabilitation program including isometric quadriceps and range-of-motion exercises the day after surgery. A non-weight-bearing regimen was prescribed for one week, followed by partial weight-bearing exercise. Full weight-bearing exercise was permitted two weeks postoperatively. Casts or supportive devices were never applied.
2.2. Radiographic assessment For radiographic assessment, an anteroposterior weight-bearing radiograph of the knee was taken at postoperative one, three, six, 12, 18, and 24 months. The presence of an LHF was assessed using the classification previously described by Takeuchi et al. [14]. Limb alignment is expressed as the femorotibial angle (FTA), defined as the lateral angle between the femoral tibial axes [2]. Bone healing with resorption and remodeling of the β-TCP wedged blocks was assessed using the radiologic rating system previously described by van Hemert et al. [17] (Table 2). Delayed bone healing was defined as no radiologic change to phase 2 or greater at postoperative three months.
2.3. Statistical analysis Statistical analysis was carried out using BellCurve for Excel version 2.21 (Social Survey Research Information, Tokyo, Japan). Pearson's chi-squared tests were used to test for significant differences with respect to distribution in the phase classification of bone healing. Multivariate logistic regression was used to identify risk factors for delayed bone healing. An adjusted p value b.05 was considered significant. A power calculation indicated that a sample size of 324 could detect a difference in progression of bone healing with an effect size of 0.2, 5% probability of a type I error and power of 80%. The intra- and inter-rater reliabilities of radiographic evaluation were assessed by calculating intraclass correlation coefficients.
Table 1 Demographic data. Number of patients (knees) Male Female Age (years) Body mass index (kg/m2) Size of opening gap (mm) Preop. FTA (degrees) Postop. FTA (degrees)
283 (350) 87 (109) 196 (241) 65.8 ± 8.9 25.2 ± 3.9 13.1 ± 2.8 181.9 ± 2.5 169.7 ± 2.8
FTA, femorotibial angle.
Please cite this article as: K. Kumagai, S. Yamada, S. Nejima, et al., Lateral hinge fracture delays healing of the osteotomy gap in opening wedge high tibial osteotomy wi..., The Knee, https://doi.org/10.1016/j.knee.2019.10.027
K. Kumagai et al. / The Knee xxx (xxxx) xxx
3
Table 2 Phase classification of radiographic bone healing after opening wedge high tibial osteotomy by van Hemert [17]. Phase
Explanation
1 2 3 4 5
Osteopenic bone, rounded osteotomy sites, clear distinction between β-TCP and bone Whitening of sites and blurred distinction between β-TCP and bone Distinction between β-TCP and bone slightly visible, though healed osteotomy Full reformation, though osteotomy recognizable, no β-TCP No sign of osteotomy
Vascular phase Calcification phase Osteoblastic phase Consolidation phase Full remodeling
3. Results 3.1. Incidence of LHF LHFs were found in 49 knees (14%). Of these fractures, a type I fracture was observed in 39 knees, a type II fracture in four knees, and a type III fracture in six knees, according to Takeuchi's classification [14]. Breakage of the fixation plate occurred in one case with type I fracture, and revision surgery was performed two months after the initial surgery (this case was excluded from the analysis). Except for this case, fracture healing was confirmed without additional surgical treatment in all cases. There was no significant difference in the size of the opening gap between the group with LHFs (13.7 ± 3.0 mm) and the group without LHFs (13.0 ± 2.7 mm) (P = .112).
3.2. Radiographic assessments of bone healing Assessments of bone healing using the radiologic rating system described by van Hemert [17] are summarized with or without LHFs in Table 3. A significant difference was found in the progression of the bone healing phase at each time point. The ratio of phase 2 was lower in the knees with LHFs than in those without LHFs at postoperative three months. Similarly, the ratio of phase 3 was lower in the knees with LHFs than in those without LHFs at postoperative six and 12 months. Overall, the osteotomy gap showed slower progression of radiographic healing with an LHF than without an LHF. In the knees with LHFs, progression to phase 2 was observed almost at the same time as healing of the LHF (Figure 1). Representative cases with or without LHFs showing progression of radiographic bone healing are in Figure 2. The inter-rater reliability for assessment of bone healing according to the radiologic rating system of van Hemert was substantial, with a kappa value of 0.78 (0.74–0.82). The intra-rater reliability at more than two-month intervals was almost perfect, with a kappa value of 0.89 (0.86–0.91).
3.3. Factors affecting progression of bone remodeling The results of multivariate logistic regression analysis for factors affecting progression of bone healing are summarized in Table 4. The rate of LHF was significantly higher in knees with delayed bone healing. LHF was the only factor preventing the progression of bone healing. Age, sex, body mass index (BMI), size of the opening gap, and postoperative FTA did not affect progression of bone healing.
Table 3 Radiographic classification of bone healing phase in ostotomy gap with or without LHF. Time
1 month
Fracture Phase
1
3 months
6 months
12 months
(+)
(−)
(+)
(−)
(+)
(−)
(+)
49 (100%)
272 (90%) 29 (10%)
38 (78%) 11 (22%)
26 (9%) 272 (91%) 3 (1%)
9 (18%) 38 (78%) 2 (4%)
1 (0.3%) 225 (75%) 75 (25%)
2 (4%) 31 (63%) 16 (33%)
2 3 4
18 months
24 months
(−)
(+)
(−)
(+)
72 (24%) 228 (76%) 1 (0.3%)
18 (37%) 30 (61%) 1 (2%)
21 (7%) 269 (89%) 11 (4%)
7 10 (14%) (3%) 38 242 (78%) (80%) 3 45 (6%) (15%) 1 4 (2%) (1%) 0.0046
5 P value
0.0233
b0.001
b0.001
b0.001
b0.001
(−)
The values are given as the number of knees with the percentage in parentheses. LHF, lateral hinge fracture.
Please cite this article as: K. Kumagai, S. Yamada, S. Nejima, et al., Lateral hinge fracture delays healing of the osteotomy gap in opening wedge high tibial osteotomy wi..., The Knee, https://doi.org/10.1016/j.knee.2019.10.027
4
K. Kumagai et al. / The Knee xxx (xxxx) xxx
Figure 1. Rate of phase 2 reached osteotomy gap and healing of lateral hinge fracture (LHF).
4. Discussion The most important finding of the present study was that LHFs affected the progression of radiographic bone healing in the osteotomy gap after OWHTO using a synthetic bone graft. LHF was the only factor that delayed the healing of the osteotomy gap, whereas age, sex, BMI, size of the opening gap, and postoperative FTA did not affect it. These results support our hypothesis that LHF is associated with delayed bone healing after OWHTO with synthetic bone grafting. The role of bone grafting for the opening gap is still controversial. Several systematic reviews and meta-analyses found no definitive advantages with the use of any bone grafts in terms of union rates and loss of correction [4–6]. However, a large opening gap without bone grafting delays filling of the opening gap [15,18]. Furthermore, with respect to biomechanical properties, a synthetic bone graft for OWHTO provides additional initial stability [19] and has the potential to allow early full weight-bearing in combination with rigid plate fixation [3]. In addition to the biomechanical issues, biocompatibility, absorbability, and osteoconductivity are important properties in the synthetic bone graft. Since these properties depend on the kind of materials, as well as the shape, porosity, etc., the progression of bone healing differs among the previous reports [8,11,12,20,21]. The βTCP wedged blocks with 60% porosity that were used as a synthetic bone substitute in the present study showed a slow process
Figure 2. Progression of bone healing in the osteotomy gap with or without a lateral hinge fracture (LHF). The radiographs of the osteotomy gap without LHF show phase 1 at 1 month, phase 2 at 3 months, phase 3 at 6, 12, and 18 months, and phase 4 at 24 months (left panels). The radiographs of the osteotomy gap with LHF show phase 1 at 1 and 3 months, phase 2 at 6 months, and phase 3 at 12, 18, and 24 months (right panels). Arrowheads indicate LHF. Union of LHF is observed at 6 months, and thereafter the osteotomy gap shows progression of bone healing.
Please cite this article as: K. Kumagai, S. Yamada, S. Nejima, et al., Lateral hinge fracture delays healing of the osteotomy gap in opening wedge high tibial osteotomy wi..., The Knee, https://doi.org/10.1016/j.knee.2019.10.027
K. Kumagai et al. / The Knee xxx (xxxx) xxx
5
Table 4 Multivariate logistic regression of factors affecting delayed bone healing. Factors
Age (years) Sex (male, %) Body mass index (kg/m2) Size of opening gap (mm) Postoperative FTA (degrees) LHF (%)
Normal healing
Delayed healing
(n = 286)
(n = 64)
65.9 ± 8.7 30.4 25.3 ± 3.9 12.9 ± 2.7 169.9 ± 2.8 3.8
65.4 ± 9.9 34.3 25.2 ± 4.0 14.1 ± 3.1 169.2 ± 2.7 59.4
Odds Ratio
95% confidence interval
P value
0.974 1.212 0.813 1.152 0.906 46.784
0.930–1.021 0.399–3.682 0.529–1.247 0.967–1.372 0.792–1.038 19.126–114.441
0.271 0.735 0.343 0.113 0.154 b0.001
FTA, femorotibial angle. LHF, lateral hinge fracture.
of bone healing in comparison with the other reports using β-TCP with different porosity and shapes [13,17,22]. This study demonstrated further delay of bone healing in the osteotomy gap of the knees with LHFs. The lateral cortical hinge contributes to primary stability at the osteotomy site, and disruption of the lateral cortex brings about instability leading to delayed bone healing at the osteotomy site [23]. Unstable LHFs are associated with a particularly high risk of delayed bone healing [15,16], although bone union also depends on other factors such as smoking, BMI, fixation device, etc. [24–26]. Bone formation after OWHTO progressed from the lateral hinge to the medial direction with or without bone grafting [15,27]. The present study demonstrated that progression to phase 2 was associated with the timing of fracture healing. Namely, the initial response to the bone substitute does not appear to occur without fracture healing in cases with LHFs. The incidence of LHF associated with OWHTO varies widely in the literature (0–50%) [8,14,16,24,28,29], implying that it is one of the frequent complications with this procedure. To avoid delayed healing of the osteotomy site with synthetic bone substitutes, care must be taken not to break the lateral cortical hinge in OWHTO. In cases of LHF, it is likely that early fracture healing is important to avoid delayed union at the osteotomy site. This study has several limitations. First, the follow-up time of two years was not very long. The current series assessed the early phase of bone healing, and most cases did not achieve complete remodeling. Second, the present series included no younger population. This may contribute to the results that age was not correlated with progression of bone healing. Third, only anteroposterior radiographs were used for assessment of bone healing. 5. Conclusion LHF is associated with delayed bone healing after OWHTO with synthetic bone grafting. Source of funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Declaration of competing interest The authors declare that they have no conflict of interest. References [1] Coventry MB, Ilstrup DM, Wallrichs SL. Proximal tibial osteotomy. A critical long-term study of eighty-seven cases. J Bone Joint Surg Am 1993;75:196–201. [2] Koshino T, Yoshida T, Ara Y, Saito I, Saito T. Fifteen to twenty-eight years' follow-up results of high tibial valgus osteotomy for osteoarthritic knee. Knee 2004;11: 439–44. [3] Saito T, Kumagai K, Akamatsu Y, Kobayashi H, Kusayama Y. Five- to ten-year outcome following medial opening-wedge high tibial osteotomy with rigid plate fixation in combination with an artificial bone substitute. Bone Joint J 2014;96-B:339–44. [4] Han JH, Kim HJ, Song JG, Yang JH, Bhandare NN, Fernandez AR, et al. Is bone grafting necessary in opening wedge high tibial osteotomy? A meta-analysis of radiological outcomes. Knee Surg Relat Res 2015;27:207–20. [5] Lash NJ, Feller JA, Batty LM, Wasiak J, Richmond AK. Bone grafts and bone substitutes for opening-wedge osteotomies of the knee: a systematic review. Arthroscopy 2015;31:720–30. [6] Slevin O, Ayeni OR, Hinterwimmer S, Tischer T, Feucht MJ, Hirschmann MT. The role of bone void fillers in medial opening wedge high tibial osteotomy: a systematic review. Knee Surg Sports Traumatol Arthrosc 2016;24:3584–98. [7] Koshino T, Murase T, Saito T. Medial opening-wedge high tibial osteotomy with use of porous hydroxyapatite to treat medial compartment osteoarthritis of the knee. J Bone Joint Surg Am 2003;85-A:78–85. [8] Ozalay M, Sahin O, Akpinar S, Ozkoc G, Cinar M, Cesur N. Remodeling potentials of biphasic calcium phosphate granules in open wedge high tibial osteotomy. Arch Orthop Trauma Surg 2009;129:747–52. [9] Tanaka T, Kumagae Y, Saito M, Chazono M, Komaki H, Kikuchi T, et al. Bone formation and resorption in patients after implantation of beta-tricalcium phosphate blocks with 60% and 75% porosity in opening-wedge high tibial osteotomy. J Biomed Mater Res B Appl Biomater 2008;86:453–9. [10] Gaasbeek RD, Toonen HG, van Heerwaarden RJ, Buma P. Mechanism of bone incorporation of beta-TCP bone substitute in open wedge tibial osteotomy in patients. Biomaterials 2005;26:6713–9. [11] Onodera J, Kondo E, Omizu N, Ueda D, Yagi T, Yasuda K. Beta-tricalcium phosphate shows superior absorption rate and osteoconductivity compared to hydroxyapatite in open-wedge high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 2014;22:2763–70.
Please cite this article as: K. Kumagai, S. Yamada, S. Nejima, et al., Lateral hinge fracture delays healing of the osteotomy gap in opening wedge high tibial osteotomy wi..., The Knee, https://doi.org/10.1016/j.knee.2019.10.027
6
K. Kumagai et al. / The Knee xxx (xxxx) xxx
[12] Jung KA, Lee SC, Ahn NK, Hwang SH, Nam CH. Radiographic healing with hemispherical allogeneic femoral head bone grafting for opening-wedge high tibial osteotomy. Arthroscopy 2010;26:1617–24. [13] Kraal T, Mullender M, de Bruine JH, Reinhard R, de Gast A, Kuik DJ, et al. Resorbability of rigid beta-tricalcium phosphate wedges in open-wedge high tibial osteotomy: a retrospective radiological study. Knee 2008;15:201–5. [14] Takeuchi R, Ishikawa H, Kumagai K, Yamaguchi Y, Chiba N, Akamatsu Y, et al. Fractures around the lateral cortical hinge after a medial opening-wedge high tibial osteotomy: a new classification of lateral hinge fracture. Arthroscopy 2012;28:85–94. [15] Goshima K, Sawaguchi T, Shigemoto K, Iwai S, Nakanishi A, Inoue D, et al. Large opening gaps, unstable hinge fractures, and osteotomy line below the safe zone cause delayed bone healing after open-wedge high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 2019;27:1291–8. [16] Schroter S, Freude T, Kopp MM, Konstantinidis L, Dobele S, Stockle U, et al. Smoking and unstable hinge fractures cause delayed gap filling irrespective of early weight bearing after open wedge osteotomy. Arthroscopy 2015;31:254–65. [17] van Hemert WL, Willems K, Anderson PG, van Heerwaarden RJ, Wymenga AB. Tricalcium phosphate granules or rigid wedge preforms in open wedge high tibial osteotomy: a radiological study with a new evaluation system. Knee 2004;11:451–6. [18] El-Assal MA, Khalifa YE, Abdel-Hamid MM, Said HG, Bakr HM. Opening-wedge high tibial osteotomy without bone graft. Knee Surg Sports Traumatol Arthrosc 2010;18:961–6. [19] Takeuchi R, Bito H, Akamatsu Y, Shiraishi T, Morishita S, Koshino T, et al. In vitro stability of open wedge high tibial osteotomy with synthetic bone graft. Knee 2010;17:217–20. [20] Lee DY, Lee MC, Ha CW, Kyung HS, Kim CW, Chang MJ, et al. Comparable bone union progression after opening wedge high tibial osteotomy using allogenous bone chip or tri-calcium phosphate granule: a prospective randomized controlled trial. Knee Surg Sports Traumatol Arthrosc 2019;27:2945–50. [21] Oh KJ, Ko YB, Jaiswal S, Whang IC. Comparison of osteoconductivity and absorbability of beta-tricalcium phosphate and hydroxyapatite in clinical scenario of opening wedge high tibial osteotomy. J Mater Sci Mater Med 2016;27:179. [22] Tanaka T, Kumagae Y, Chazono M, Kitasato S, Kakuta A, Marumo K. A novel evaluation system to monitor bone formation and beta-tricalcium phosphate resorption in opening wedge high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 2015;23:2007–11. [23] Miller BS, Dorsey WO, Bryant CR, Austin JC. The effect of lateral cortex disruption and repair on the stability of the medial opening wedge high tibial osteotomy. Am J Sports Med 2005;33:1552–7. [24] Dexel J, Fritzsche H, Beyer F, Harman MK, Lutzner J. Open-wedge high tibial osteotomy: incidence of lateral cortex fractures and influence of fixation device on osteotomy healing. Knee Surg Sports Traumatol Arthrosc 2017;25:832–7. [25] Meidinger G, Imhoff AB, Paul J, Kirchhoff C, Sauerschnig M, Hinterwimmer S. May smokers and overweight patients be treated with a medial open-wedge HTO? Risk factors for non-union. Knee Surg Sports Traumatol Arthrosc 2011;19:333–9. [26] Siboni R, Beaufils P, Boisrenoult P, Steltzlen C, Pujol N. Opening-wedge high tibial osteotomy without bone grafting in severe varus osteoarthritic knee. Rate and risk factors of non-union in 41 cases. Orthop Traumatol Surg Res 2018;104:473–6. [27] Kobayashi H, Akamatsu Y, Kumagai K, Kusayama Y, Saito T. Radiographic and computed tomographic evaluation of bone union after medial opening wedge high tibial osteotomy with filling gap. Knee 2017;24:1108–17. [28] Lee SS, Celik H, Lee DH. Predictive factors for and detection of lateral hinge fractures following open wedge high tibial osteotomy: plain radiography versus computed tomography. Arthroscopy 2018;34:3073–9. [29] van Houten AH, Heesterbeek PJ, van Heerwaarden RJ, van Tienen TG, Wymenga AB. Medial open wedge high tibial osteotomy: can delayed or nonunion be predicted? Clin Orthop Relat Res 2014;472:1217–23.
Please cite this article as: K. Kumagai, S. Yamada, S. Nejima, et al., Lateral hinge fracture delays healing of the osteotomy gap in opening wedge high tibial osteotomy wi..., The Knee, https://doi.org/10.1016/j.knee.2019.10.027