Is a synthetic augmentation in medial open wedge high tibial osteotomies superior to no augmentation in terms of bone-healing?

Implant Removal After Medial Opening Wedge High Tibial Osteotomy Provides Implant-Related Pain Relief and Functional Improvement

PURPOSE

To investigate the incidence of implant-related pain after medial opening wedge high tibial osteotomy (MOWHTO) using a locking plate, to determine whether implant removal provides pain relief and functional improvement, and to evaluate bone healing and loss of correction after implant removal.

METHODS

Between March 2014 and September 2017, MOWHTO was performed without bone graft. The inclusion criteria were patients who underwent implant removal after MOWHTO and were followed up for a minimum of 2 years. Patients were evaluated for implant removal 1 and 2 years after surgery. Clinical and functional evaluations were conducted to investigate implant-related pain using the visual analog scale, Lysholm score, and Tegner score. The radiographic indices measured were the gap-filling rate, weightbearing line (WBL) ratio, hip-knee-ankle angle (HKAA), medial proximal tibial angle (MPTA), and posterior tibial slope angle (PTSA).

RESULTS

A total of 55 patients were enrolled. Fifty-one (92.7%) patients experienced implant-related pain prior to implant removal, with 43 and 8 patients reporting mild pain and moderate pain, respectively. At 1 and 2 years after implant removal, mild pain occurred in 6 (10.9%) and 5 (9.1%) patients, respectively. The remaining patients reported no implant-related pain. Prior to implant removal and 1 year after implant removal, the Lysholm score improved from 77.0 ± 5.6 to 86.8 ± 5.7 (P < .001), and the Tegner score improved from 3.3 ± 1.2 to 3.9 ± 1.3 (P < .001). The mean gap-filling rate was 84.4% ± 9.6% at implant removal, and it significantly increased to 93.7% ± 5.4% and 97.4% ± 2.6% at 1 and 2 years after implant removal, respectively (P < .001). For the WBL ratio, HKAA, MPTA, and PTSA, no statistically significant differences were found after implant removal.

CONCLUSIONS

The incidence of implant-related pain after MOWHTO using the medial proximal tibial locking plate was high. Implant removal provides pain relief and functional improvement (met minimal clinically important differences). Even after implant removal, bone healing progressed gradually without a loss of correction in all patients.

LEVEL OF EVIDENCE

Level IV, case series.

Lack of Efficacy of Bone Void Filling Materials in Medial Opening-Wedge High Tibial Osteotomy: A Systematic Review and Network Meta-Analysis

PURPOSE

To systematically review the clinical and radiologic outcomes of isolated medial opening-wedge high tibial osteotomies with different bone void filling materials and to compare the outcomes by network meta-analysis.

METHODS

This systematic review and network meta-analysis included searches of Medline, Embase, Cochrane Library, Web of Science, and Scopus from inception to July 30, 2022, for clinical comparative studies comparing 2 or more bone void filling materials in patients undergoing medial opening-wedge high tibial osteotomies. We performed Bayesian random-effect network meta-analyses to summarize the evidence and applied the Grading of Recommendations Assessment, Development, and Evaluation frameworks to rate the certainty of evidence, calculate the absolute effects, and present the findings. Cochrane Risk of Bias Tool 2.0 and modified Newcastle-Ottawa Scale were used to assess the risk of bias.

RESULTS

In total, 2,755 citations were identified by our search, of which 25 eligible trials, including 10 randomized controlled trials and 15 nonrandomized comparative trials (NCTs) enrolled 1,420 participants and 6 different interventions (autografts, allografts, synthetic grafts, mixed grafts, xenografts, and without grafts). There were some concerns on the risk of bias assessment among randomized controlled trials, and the median Newcastle-Ottawa Scale score was 6 for NCTs. All fillers showed no significantly superior treatment effects when compared with unfilled group in final Knee Society Scoring, Western Ontario and McMasters Universities score, time to bone union (TBU), and loss of correction (LOC). Exceptionally, moderate-certainty evidence suggested that autograft would produce superior incidence of complete bone union (CBU) than the unfilled at postoperative 1 year (odds ratio [OR] 13.0, 95% confidence interval [CI] 1.60-95.6), whereas low- to very low-certainty evidence suggested allografts (OR 0.2, 95% CI 0.06-0.52) and synthetic grafts (OR 0.29, 95% CI 0.10-0.68) would result in inferior CBU. Low-certainty evidence suggested allografts would result in larger LOC angle than unfilled group (mean difference 1.1, 95% CI 0.1-2.3). As for TBU, low-certainty evidence suggested mixed grafts would take longer time to reach clinical bone union (mean difference -14.04, 95% CI -21.0 to -6.9).

CONCLUSIONS

There is a lack of efficacy for different bone void filling materials to result better outcomes in Knee Society Scoring, Western Ontario and McMasters Universities score, TBU, and LOC than without graft. Although applying the autografts would produce a superior possibility of radiologic CBU than other fillers, because of the inclusion of NCTs, the overall certainty of the evidence synthesis is low.

LEVEL OF EVIDENCE

Level Ⅲ, meta-analysis of Level I randomized controlled trials and Level Ⅱ∼Ⅲ non-randomized comparative trails.

Effectiveness of bone substitute materials in opening wedge high tibial osteotomy: a systematic review and meta-analysis

BACKGROUND

A meta-analysis of eligible studies was performed to evaluate the effectiveness of bone substitute materials (BSMs) in opening wedge high tibial osteotomy (OWHTO) for knee osteoarthritis.

METHODS

A systematic review and meta-analysis were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). A comprehensive literature search was performed, and studies comparing BSM with bone graft (BG) and without bone graft (WG) were included. The Cochrane risk of bias tool (version 1.0) and Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I) tool were used to assess the risk of bias for randomized controlled trials (RCTs) and non-randomized studies (NRSs), respectively. The outcomes measured were the osteotomy gap size, the occurrence rates of non-union and lateral hinge fractures, knee functional score, infection and the Visual Analogue Scale (VAS). The quality of evidences was evaluated by Grades of Recommendation, Assessment, Development and Evaluation (GRADE) Working Group system.

RESULTS

Five RCTs and eight NRS including 769 participants were included in our meta-analysis. The BSM group had a larger osteotomy gap size than the control group (MD: 0.41 mm, 95% confidence interval (CI): [0.06, 0.76], p=.02, I2=0%), with a significant difference. No significant difference was found between BSM and control group in main analysis in terms of bone non-union, but with a higher non-union rate when BSM combined with long locking plate was used. No significant differences were found in other outcome measures except for VAS from NRS subgroup. The quality of evidence for outcomes was low.

CONCLUSIONS

BSM combined with locking plate techniques offers a safe and efficient alternative option in OWHTO for osteotomy gap larger than 10 mm, but be aware of the possibility of bone non-union. Given the inherent heterogeneity and low quality of the included studies, future well-designed RCTs are essential to verify the findings.KEY MESSAGEThe treatment of the osteotomy gap is still controversial.BSM combined with a locking plate offers a safe and efficient alternative option for OWHTO with an over 10 mm of osteotomy gap over 10 mm.Due to the inherent heterogeneity and low quality of the included studies, the results should be cautiously interpreted in clinical practice.

Combined use of beta-tricalcium phosphate with different porosities can accelerate bone remodelling in open-wedge high tibial osteotomy

Background/Objective

Beta-tricalcium phosphate (β-TCP) is often used as a gap filler in open-wedge high tibial osteotomy (OWHTO). The aim of the present study was to investigate the effects of using β-TCP with different porosities on bone remodelling after OWHTO.Methods: We evaluated 29 knees in 26 patients that underwent OWHTO using β-TCP with porosities of 60% and 75% (combined group). A further 30 knees in 28 patients that underwent OWHTO using β-TCP with 60% porosity alone were allocated as a control group. In the combined group, a β-TCP block with 75% porosity was inserted into the gap at the cancellous bone site and a β-TCP block with 60% porosity was inserted into the medial cortical bone side. In the control group, a β-TCP block with 60% porosity was inserted into the osteotomy gap. The bone remodelling phases of the inserted β-TCP blocks were evaluated on standard anteroposterior radiographs using the modified van Hemert classification at 3 and 6 months post-operatively.

Results

The rate of satisfactory bone remodelling at the cancellous bone sites was 86.2% (25/29) in the combined group and 0% (0/30) in the control group at 3 months post-operatively (p<0.05), progressing to 96.6% (28/29) in the combined group and 20% (6/30) in the control group at 6 months post-operatively (p<0.05).

Conclusion

The present study demonstrated that combined use of β-TCP with high and low porosities can significantly enhance bone formation. The combined use of artificial bones with different porosities is useful for early bone remodelling in OWHTO.

Tibial cancellous bone auto-grafting for medial open-wedge high tibial osteotomy: bone void filling with tissue harvested from osteotomized medullary canal

The aim of the study was to evaluate the clinical and radiological outcomes in a series of patients undergoing open wedge high tibial osteotomy (OWHTO) using tibial cancellous autograft harvested from the osteotomized medullary canal which is not reported in the literature before. Patients with medial compartment osteoarthritis were treated with OWHTO and tibial cancellous auto- grafting performed from the osteotomized medullary canal and used for bone void filling. Seventy patients (seventy-two knees) treated with OWHTO were analyzed. All patients started partial weight-bearing with crutches the day after surgery and full-weight bearing eight weeks after surgery, according to radiological evaluation. Fifty-seven women and 13 men with a mean age of 54.2±8.1 years were evaluated in this study. The mean correction angle was 8.4±2.5° (range: 5.3°-14.3°). The osteotomy sites of all patients were grafted with tibial cancellous autografts. In all patients bony union was detected after surgery. No implant failures or major complications were en- countered. Clinical and radiological findings revealed that bone void filling with the harvested autograft from the osteotomized medullary canal may be a satisfactory and reliable option in OWHTO.

Bone healing on serial plain radiographs occurs slowly but adequately after medial opening wedge high tibial osteotomy without bone graft

PURPOSE

The purpose of this study was to prospectively investigate osteotomy gap filling rates on serial plain radiographs, and to evaluate whether alignment correction is maintained after medial opening wedge high tibial osteotomy (MOWHTO) using a locking plate without bone graft.

METHODS

Between March 2014 and June 2017, MOWHTO was performed without bone graft regardless of gap size. Radiographs were taken preoperatively, postoperatively, at 1, 3, 6, 12, 18, and 24 months after surgery. Radiographic examinations included a weight bearing long-standing anteroposterior (AP) view of the whole lower extremity, as well as, the AP, lateral, and both oblique views of the knee. Bone healing was measured on the medial oblique view of the knee. The postoperative alignment correction and its maintenance were assessed using the three radiologic parameters of the weight-bearing line (WBL) ratio, the hip-knee-ankle angle (HKAA), and the medial proximal tibial angle (MPTA) on the weight-bearing long-standing AP view of the lower extremity.

RESULTS

Fifty-two consecutive patients underwent MOWHTO, but three patients failed to follow-up for more than 24 months. A total of 49 patients were assessed in this study. The median opening gap height was 10.0 mm (IQR, 8.0-12.0; range, 7-20). On immediate post-operative radiographs, the mean gap filling was 31.4 ± 3.6%. After 1, 3, 6, 12, 18, and 24 months, the mean gap filling rates increased to 38.7 ± 4.4%, 51.4 ± 6.6%, 66.5 ± 5.1%, 84.8 ± 7.0%, 92.4 ± 5.6%, and 97.8 ± 2.3%, respectively. Statistical differences were observed between all the follow-up evaluations (P < 0.001). Statistical differences in the WBL ratio, HKAA, and MPTA were observed between preoperatively and 1 month after surgery (P < 0.001). The mean PTSA increased significantly from preoperatively to postoperatively (P < 0.001). However, no statistical differences were found between the post-operative follow-up radiographs performed for these four values.

CONCLUSION

MOWHTO using a locking plate without bone graft achieved at least 90% bone healing and had no loss in correction at 2 years postoperatively.

LEVEL OF EVIDENCE

III.

Mid-term CT assessment of bone healing after nanohydroxyapatite augmentation in open-wedge high tibial osteotomy

BACKGROUND

The aim of the present study was to confirm the effectiveness of adding nanohydroxyapatite (NHA) to a heterologous bone graft in open-wedge high tibial osteotomy (OWHTO) by measuring the bone density via multislice computed tomography (CT) of the tibial osteotomy gap in a mid-term follow-up (five years).

METHODS

Twenty-six patients undergoing OWHTO were randomly assigned to two groups: a pure graft group (Group A), in which the osteotomy gap was filled with only heterologous bone graft, and an NHA group (Group B), in which the osteotomy gap was filled with heterologous bone graft and NHA. CT was performed within one week of the operation, after two months, after 12 months and after five years. CT volume acquired in Hounsfield units (HU) was measured on three planes.

RESULTS

The normal bone density was 110.2 ± 11.7 HU. The value of mean density at five years in Group A was 296.8 ± 81.8 HU, while in Group B, it was 202.2 ± 45.1 HU, showing a density more similar to normal bone and greater bone uniformity inside the osteotomy. The difference between the two groups was statistically significant (p < 0.05). Furthermore, both groups showed excellent mid-term clinical outcomes without significant differences.

CONCLUSIONS

This study revealed that absorbability and bone formation at the osteotomy site in the NHA group was significantly higher as compared with the pure graft group at five years postoperatively.

[Management principle and clinical suggestions of osteotomy gap of opening wedge high tibial osteotomy]

OBJECTIVE

To summarize the management principle and clinical suggestions of the osteotomy gap of opening wedge high tibial osteotomy (OWHTO).

METHODS

The related literature of the osteotomy gap of OWHTO in recent years was reviewed, summarized, and analyzed.

RESULTS

Delayed union and non-union of the osteotomy gap are main complications of OWHTO. Tomofix plate, as locking steel plate, has the characteristics of angular stability and can better maintain the stability of the osteotomy gap, promote bone healing, and avoid loss of correction. There are some treatment options for the osteotomy gap site, such as, without bone, autologous bone graft, allogeneic bone graft, bone substitute materials graft, and augment factor graft to enhance bone healing. When the osteotomy gap is less than 10 mm, it achieves a good outcome without bone graft. For the obesity, lateral hinge fracture, large osteotomy gap, or correction angle more than 10°, the bone graft should be considered. In cases whose osteotomy gap is nonunion or delayed union, the autologous bone graft is still the gold standard. When the osteotomy gap repaired with the allogeneic bone graft, it is better to choose fragmented cancellous or wedge-shaped cancellous bone, combining with the locking plate technology, also can achieve better bone union. The bone substitute material of calcium-phosphorus is used in the osteotomy gap, which has the characteristics of excellent bone conduction, good biocompatibility, and resorption, combining with the locking plate technology, which can also achieve better bone union in the osteotomy gap. The augment factors enhance the bone healing of the osteotomy gap of OWHTO is still questionable. The bone union of the osteotomy gap is also related to the size of the osteotomy gap and whether the lateral hinge is broken or not.

CONCLUSION

No matter what type of materials for the osteotomy gap, OWHTO can improve the function and relieve pain for knee osteoarthritis. More randomized controlled trials are needed to provide evidence for clinical decision to determine which treatment option is better for the osteotomy gap of OWHTO.

Corrective osteotomies of femur and tibia: which factors influence bone healing?

INTRODUCTION

Corrective osteotomies of the lower limb are standard procedures in orthopedic surgery. Still, there is only limited research on factors affecting bone healing after osteotomies. We hypothesize that especially the location of the osteotomy, smoking status and BMI affect bone healing.

MATERIAL AND METHODS

The healing process of 547 patients who underwent osteotomies of the lower limb (259 female, 288 male; average 40.6 years, range 14-77) was evaluated. To assess bone healing, participants were divided into three groups by bone healing duration ( < 5/5-8/ > 8 months). Differences in healing duration related to the anatomic level of the osteotomy (diaphysis vs. metaphysis), age, gender, smoking status, BMI, and modus of the osteotomy (open vs. closed wedge) were tested for significance using an ordinal regression analysis.

RESULTS

A significant correlation between bone healing and the anatomical level of the osteotomy on femur and tibia and the patients' smoking status was found. The odds of the diaphysis considering bone healing was 0.187 (95% CI, 0.08-0.44) times that of the metaphysis (Wald χ²(1) = 14.597, p < 0.000). The odds ratio of smokers considering bone healing was 0.192 (95% CI, 0.11-0.33) times that of non-smokers (Wald χ²(1) = 35.420, p < 0.000). All other analyzed factors did not show a significant correlation with bone healing.

CONCLUSIONS

Smoking status and the localization of the osteotomy on femur and tibia (diaphysis vs. metaphysis) are significantly correlated with bone healing duration. In line with current literature emphasizing the detrimental effect of smoking on bone healing, our findings should encourage surgeons to think twice about the indication to perform osteotomies on smokers. Furthermore, if applicable, osteotomies should be performed in the metaphyseal areas of femur and tibia.

Effect of saw blade geometry on crack initiation and propagation on the lateral cortical hinge for HTO: Finite element analysis

INTRODUCTION

The hinge plays a primary role in the hold and healing of a high tibial osteotomy (HTO). Weakening of the hinge is a risk factor for failure. The aim of our study was to determine whether the geometry of the saw blade's cutting edge impacts crack initiation or propagation on the hinge.

HYPOTHESIS

A certain cutting edge geometry exists that will reduce this risk.

MATERIALS AND METHODS

A finite element model with transverse isotropic elastic bone properties was created. A 1.27-mm thick saw cut (full thickness in anteroposterior direction) was made leaving a 1cm lateral cortical hinge. Three different cutting edge geometries were compared: rectangular, U-shaped, V-shaped. Opening of the osteotomy was done over 1mm for 1 s by a load applied distally with the proximal portion fixed. In the first simulation, no crack was initiated at the hinge, while in the second simulation, the beginnings of a 2mm crack angled upward at 15° was added. These two simulations were used to identify whether a local stress riser was present at the hinge. This information was used to calculate the energy release rate to the hinge, which corresponds to the energy needed to initiate and propagate a crack on the hinge.

RESULTS

In the first simulation (no crack initiation), a rectangular saw blade geometry resulted in the lowest local stress concentration. In the second simulation (with crack initiation), the U-shaped geometry resulted in the lowest local stress concentration. The U-shaped geometry had the lowest energy release rate, meaning that it was the least likely to initiate and propagate a crack on the lateral cortical hinge.

DISCUSSION/CONCLUSION

Keeping the inherent limitations related to computer modelling in mind, our findings show that a U-shaped cutting edge is least likely to initiate or propagate a crack since it has the lowest energy release rate. This confirms our hypothesis.

LEVEL OF EVIDENCE

V, expert opinion.

Editorial Commentary: Go Autologous or Go Home: Open-Wedge High Tibial Osteotomies Do Not Benefit From Synthetic Bone Grafting

Open-wedge high tibial osteotomies result in a gap on the medial aspect of the proximal tibia and filling the gap with autologous bone graft may reduce nonunion rates and result in better functional outcomes. Autologous bone grafts are the golden standard, but synthetic bone fillers are an attractive option; however, current evidence suggests that synthetic bone grafts do not result in higher union rates and may be detrimental during open-wedge osteotomies.

[Bone void fillers in osteotomies : If, when, and which type?]

Medial opening wedge high tibial osteotomy (HTO) is an established procedure for treating medial osteoarthritis of the knee. In order to achieve the desired amount of correction, the osteotomy gap is opened, which creates a bone void in the medial aspect of the proximal tibia. The resulting bone void can either be left alone or be addressed by interposing a variety of different bone void fillers. Autologous and allogenic fillers can be distinguished from synthetic materials. Up to now, few studies have dealt with the usefulness and necessity for bone void fillers in HTO. The following article provides an overview on the currently used bone void fillers, their specific advantages and disadvantages and their influence on clinical and radiographic outcome after HTO.

Comparison of bone healing and outcomes between allogenous bone chip and hydroxyapatite chip grafts in open wedge high tibial osteotomy

Allogenous bone chips and hydroxyapatite (HA) chips have been known as good options for filling an inevitable void after open wedge high tibial osteotomy (OWHTO). However, there are concerns regarding bone healing after the use of these grafts. The purpose of this study was to compare the bone healing represented by the osteoconductivity and absorbability between allogenous bone chips and HA chips in OWHTO. The outcomes of bone healing of 53 patients who received an allogenous bone chip graft and 41 patients who received an HA chip graft were retrospectively evaluated, and the results were compared between the two groups. Osteoconductivity and absorbability were serially evaluated for the assessment of bone healing at 6 weeks, 3 months, 6 months, and 1 year postoperatively. The osteoconductivity of the allogenous bone chips was greater than that of the HA chips at 6 weeks postoperatively (p < 0.05). However, there were no statistically significant differences from 3 months to 1 year postoperatively. The absorbability showed no statistically significant differences 6 weeks and 3 months after OWHTO; however, the allogenous bone chip group showed a greater absorbability at 6 months and 1 year postoperatively (42.8 ± 14.2 vs. 34.6 ± 13.8, p = 0.006 at 6 months postoperatively; 54.6 ± 14.4 vs. 43.0 ± 14.0, p < 0.001 at 1 year postoperatively). However, the two graft materials showed similar results of HKA angle, WBL ratio, posterior tibial slope.

The role of bone void fillers in medial opening wedge high tibial osteotomy: a systematic review

PURPOSE

A variety of bone void filling materials and methods are available in opening medial wedge HTO (OWHTO). The pertinent question revolves around if and when bone void fillers are needed. The primary purpose of this study was to systematically review outcomes and complications after OWHTO with and without the use of bone void fillers.

METHODS

The EMBASE, PubMed\MEDLINE, Cochrane Library and Google Scholar databases were searched to identify articles that reported OWHTO results using different bone void fillers until March 2016. Only articles reporting the exact bone void filler type, the opening gap size and the fixation method were included. The extracted data included the study design, demographic data, the radiological and clinical results and complication rates. Outcomes were analysed with regard to bone void filler type, and comparison was made between the groups (allograft, autograft, synthetic bone void filler and OWHTO without bone void filling).

RESULTS

Twenty-two articles reporting the results of 1421 OWHTO met the inclusion criteria. In total, 647 osteotomies were completed with allogeneic graft as bone void filler, 367 with synthetic materials, 199 with autograft and 208 without any bone void filling material. The maximum opening gap size was similar in all groups with mean of 9.8 mm (range 4-17.5 mm). Locking plate fixation was used in 90 % of the osteotomies that were completed without bone void filler, while all allograft cases and more then 90 % of the autograft cases were done with non-locking systems. The highest rates of non-union (1.1 %) were seen in the synthetic group, compared to 0.5 % in the all the other groups.

CONCLUSIONS

This systematic review showed no definitive advantages for OWHTO with any bone void filler in terms of union rates and loss of correction. Moreover, the use of autografts or allografts showed more favourable outcomes than synthetic bone substitutes. OWHTO with gaps smaller then 10 mm and rigid fixation might be successfully managed without bone grafting. However, when bone grafting is needed, autograft bone provides higher rates of clinical and radiographic union. The use of synthetic bone substitutes in OWHTO cannot be recommended.

LEVEL OF EVIDENCE

III.