Faster bone union progression and less sclerosis at the osteotomy margin after medial opening-wedge high tibial osteotomy using highly porous β-tricalcium phosphate granules versus allogeneic bone chips: A matched case-control study

Gap Volume Based on Computed Tomography Measurement Is a Strong Risk Factor for Delayed Gap Healing After Open-Wedge High Tibial Osteotomy

PURPOSE

To identify factors that affect delayed gap healing after open-wedge high tibial osteotomy (OWHTO) and to determine whether large gap volume is a predictor of delayed gap healing.

METHODS

This retrospective study analyzed biplane OWHTO performed between 2019 and 2023 for knee osteoarthritis or osteonecrosis. The minimum follow-up period was 1 year. Delayed gap healing was defined when the medial half of the osteotomy gap area had not reached the consolidation phase by 6 months after surgery based on anteroposterior knee radiographs. Gap volume was calculated from computed tomography images. Logistic regression was performed using body height, smoking, correction angle, hinge fracture, flange thickness, and gap volume. A gap volume cutoff value for delayed gap healing was determined with receiver operating characteristic curve analysis. Gap volume was predicted with multiple linear regression.

RESULTS

There were 80 knees in 71 patients (36 men and 44 women). The mean gap volume was 7.6 cm3. Gap healing rates at 3, 6, 9, and 12 months after surgery were 26%, 65%, 89%, and 100%, respectively. There were 25 knees with delayed gap healing. Male sex was not a significant risk factor when adjusted for body height. Multivariate logistic regression revealed that only larger gap volume was a significant risk factor (odds ratio, 1.45; P = .006). The gap volume cutoff value was 7.6 cm3, with an area under the curve of 0.74. Tall body height and a large correction angle (both P < .001) were associated with a significantly larger gap volume (R2 = 0.73).

CONCLUSIONS

Large gap volume is the most important risk factor for delayed gap healing after OWHTO. Gap volume can be predicted based on body height and correction angle. When OWHTO with substantial correction is planned for tall men, surgeons should be aware of possibly delayed gap healing.

LEVEL OF EVIDENCE

Level IV, retrospective case-control study.

Midfoot Joint Arthrodesis Using Compression Plate With Lag Screw Augmenting With Highly Porous β-Tricalcium Phosphate and Bone Marrow Aspirate Concentrate

BACKGROUND

There is still a controversy regarding the most optimal fixation instruments and bone graft materials for midfoot joint arthrodesis. We present the results of midfoot joint arthrodesis using compression plate with lag screw augmenting with highly porous β-tricalcium phosphate (β-TCP) and bone marrow aspirate concentrate (BMAC).

METHODS

We performed a retrospective review of patients undergoing midfoot joint arthrodesis using compression plate with lag screw augmenting with highly porous β-TCP and BMAC from January 2014 to May 2019. The radiographic bony union rate was investigated. Postoperative complications and reoperations were also reviewed. A total of 36 patients (37 feet) including 75 joints were available in this study.

RESULTS

A high union rate was achieved as of 97.3% in 73 of 75 joints. Nonunion occurred in 2 patients including 2 joints. Other than nonunion, there were no major complications such as deep infection. Minor complications (5 of 75 joints, 6.7%) included hardware irritations. Reoperations were required in 1 patient for revision of arthrodesis and symptomatic hardware removal was performed in all 5 hardware irritation cases.

CONCLUSION

Based on our results, the fixation construct of compression plate with lag screw augmenting with highly porous β-TCP and BMAC is safe and effective for midfoot joint arthrodesis with an excellent union rate and a low complication rate.

LEVEL OF EVIDENCE

IV, retrospective case series.

An anatomical artificial bone implant can improve three-dimensional correction accuracy in open-wedge high tibial osteotomy

BACKGROUND

An anatomical artificial bone implant inserted into the osteotomy gap might be useful for accurate alignment correction during open-wedge high tibial osteotomy (OWHTO). The aims of this study were to evaluate morphological variation in the osteotomy surface, identify an anatomical implant's shape, and verify its usefulness for accurate three-dimensional (3D) correction.

METHODS

Virtual OWHTO was performed with preoperative 3D computed tomography data from 100 knees. The tibial contour in the osteotomy plane was analyzed using principal component analysis to determine implant shape. An anatomical artificial bone implant with a 10° correction angle was made with a synthetic bone substitute. Coronal correction accuracy and changes in posterior tibial slope (PTS) and rotation were evaluated on eight cadaver knees that received the anatomical artificial bone implant and clinically on 85 in vivo knees that received conventional wedge-shaped spacers.

RESULTS

The single-shape anatomical artificial bone implant was designed to occupy a posteromedial 30 × 25 mm region and had high contour congruency (mean mismatch, 0.73 mm; mean contact area coverage, 97.5%). Gap opening angle with the anatomical artificial bone implant was precise, avoiding excessive PTS change (mean, 0.6°) and rotational change (mean, 0.5°). In contrast, both PTS and rotational change with conventional spacers increased by a mean of 2.9°.

CONCLUSIONS

An anatomical artificial bone implant derived from the mean shape of 100 knees had high and consistent contour congruency. The anatomical artificial bone implant inserted with 3D surgical guidance provided accurate gap opening, reducing PTS change to less than 1° during OWHTO.

Radiographic Assessment of Bone Union in Proximal Tibia and Distal Femur Osteotomies: A Systematic Review

Background

Osteotomies around the knee are a well-established treatment option for early and moderate unicompartmental osteoarthritis combined with a lower extremity malalignment. Moreover, osteotomies are often combined with cartilage treatment. Current image-based bone union assessments lack an accepted definition despite widespread use in research and clinical settings. The aim of this systematic review was to identify definitions and classification systems for bone union on radiographs after a proximal tibia or distal femur osteotomy.

Methods

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we systematically searched MEDLINE and Embase database, applying specific inclusion and exclusion criteria. Two independent reviewers screened abstracts and full-texts. The modified Cochrane Risk of Bias Tool and Risk of Bias in Nonrandomized Studies of Interventions tool were used. Data extraction included study characteristics, imaging modality, bone union definition, classification systems, assessment of gap fillers, use of modifiers, and osteotomy type.

Results

Of the 1,180 screened titles and abstracts, 105 studies were included, with the majority (69 studies [65.7%]) using a retrospective design. Fifty-five studies (52.4%) defined bone union based on one or more criteria, while 50 studies (47.6%) used a classification system. There were 13 different criteria for bone union and 9 different classification systems. Interestingly, none of the classification systems incorporated negative criteria, such as hardware failure. Notably, 137 studies (49.1%) described bone union as either a primary or secondary outcome but do not describe a system for assessing bone union.

Conclusion

This systematic review highlights the lack of consensus in the literature in defining bone union after a proximal tibia or distal femur osteotomy, revealing many criteria and different classifications. None of the classification systems were applicable to osteotomies with and without gap filler. This systematic review shows the need for a straightforward, reproducible, and accurate method to assess bone union after a proximal tibia or distal femur osteotomy.

Level of Evidence

Level III. See Instructions for Authors for a complete description of levels of evidence.

Bone Healing and Clinical Outcome Following Medial Opening-wedge High Tibial Osteotomy Using Wedge-Shaped Cancellous Allograft

OBJECTIVE

Medial opening-wedge high tibial osteotomy (MOWHTO) is considered to be an effective treatment for symptomatic knee osteoarthritis (KOA) of isolated the medial compartment with varus alignment of the lower extremity. However, the choice of material to fill the void remains controversial. This study aims to evaluate the bone union of the osteotomy gap using a novel wedge-shaped cancellous allograft after MOWHTO and its effect on clinical outcomes.

METHODS

All patients who underwent MOWHTO using a novel wedge-shaped cancellous allograft combined with TomoFix locking compression plate (LCP) fixation between January 2016 and July 2020 were enrolled. The radiographic parameters including hip-knee-ankle angle (HKAA), medial proximal tibial angle (MPTA), femorotibial angle (FTA) and posterior tibial slope angle (PTSA) were measured between pre-operative and post-operative radiographs. Knee Society score (KSS) and range of motion (ROM) were assessed preoperatively and at last follow-up. Patients included in this study were divided into two groups according to the correction angle: small correction group (< 10°; SC group) and large correction group (≥ 10°; LC group). The modified Radiographic Union score for tibial fractures (mRUST) was used to assess the difference in bone healing between the two groups at 1, 3, 6, and 12 months postoperatively and at the final follow-up. A paired student's t test was conducted for comparison of differences of the relevant data pre-operatively and post-operatively.

RESULTS

A total of 82 patients (88 knees) were included in this study. The HKAA, MPTA, FTA and PTSA increased from -6.4° ± 3.0°, 85.1° ± 2.6°, 180.1° ± 3.2° and 7.7° ± 4.4° preoperatively to 1.2° ± 4.3° (p < 0.001), 94.4° ± 3.3° (p < 0.001), 171.0° ± 2.8° and 11.8° ± 5.8° (p < 0.001) immediately postoperatively, respectively. However, no significant statistic difference was found in above-mentioned parameters at last follow-up compared to immediate postoperative data (p > 0.05). All patients in this study achieved good bone healing at the final follow-up and no significant differences in mRUST scores were seen between the SC group and LC group. The KSS-Knee score and KSS-Function score improved significantly from 55.4 ± 3.7 and 63.3 ± 4.6 preoperatively to 86.4 ± 2.8 (p < 0.001) and 89.6 ± 2.9 (p < 0.001) at last follow-up, respectively. Nevertheless, there was no significant difference in ROM between pre-operation and last follow-up (p > 0.05).

CONCLUSION

For MOWHTO, the wedge-shaped cancellous allograft was a reliable choice for providing good bone healing and clinical outcomes.

Effect of lateral hinge fractures for bone union and clinical outcomes following opening-wedge distal tibial tubercle osteotomy in comparison with opening-wedge high tibial osteotomy

PURPOSE

Although the effects of lateral hinge fractures (LHF) on bone union and clinical outcomes after opening-wedge high tibial osteotomy (OWHTO) have been established, the effects of LHF after opening-wedge distal tibial tubercle osteotomy (OWDTO) are unclear. We hypothesised that LHF after OWDTO would be associated with delayed bone union and result in poorer clinical outcomes than expected for LHF after OWHTO.

METHODS

This study enrolled 100 patients, with 50 OWDTO patients (18 men; mean age, 63.2 years) and 50 OWHTO patients compared based on the propensity score matched analysis. The effect of LHF on bone union was compared between the groups. Clinical outcomes were assessed using the Lysholm score and the Knee Injury and Osteoarthritis Outcome Score (KOOS) at the mean follow-up of 28 months.

RESULTS

There was no between-group difference in the incidence rate of LHF. However, the rate of bone union at the anterior flange in the presence of an LHF was significantly lower in the OWDTO (26%) than in the OWHTO (80%) 3 months postoperatively (p < 0.05), but no difference was observed 12 months postoperatively. The Lysholm score was significantly lower for patients with LHF following OWDTO than for OWDTO patients without LHF or OWHTO patients with/without LHF 3 and 12 months postoperatively (p < 0.001); Lysholm score and KOOS were not different at the final follow-up.

CONCLUSIONS

LHF after OWDTO was associated with delayed bone union and poor clinical outcomes until 12 months. This information can guide decisions regarding the indications and the management of patients after OWDTO.

LEVEL OF EVIDENCE

IV.

The Efficiency of Highly Porous β-Tricalcium Phosphate With Bone Marrow Aspirate Concentrate in Midfoot Joint Arthrodesis

BACKGROUND

Nonunion is one of the most common and devastating complications following midfoot joint arthrodesis. Many different types of bone grafts and bone substitutes have been used to promote osseous fusion. However, there is no consensus on the gold standard bone grafting material and whether biologic materials should be used alone or in combination. The purpose of this study is to investigate the efficiency of highly porous β-tricalcium phosphate (β-TCP) with bone marrow aspirate concentrate (BMAC) in midfoot joint arthrodesis.

METHODS

This retrospective comparative study included patients who underwent midfoot joint arthrodesis using compression screws. Patients were classified into 2 groups: arthrodesis with highly porous β-TCP and BMAC (group A) and arthrodesis without them (group B). The osseous union rate was compared between the 2 groups. A total of 44 patients (46 feet) including 89 joints were included in this study.

RESULTS

There was a significant difference in the union rate between the 2 groups: 91.5% (43/47 joints) in arthrodesis with highly porous β-TCP and BMAC (group A) and 76.2% (32/42 joints) in arthrodesis without highly porous β-TCP and BMAC (group B; P = .048).

CONCLUSION

This study investigated the efficiency of highly porous β-TCP and BMAC to promote bony healing in midfoot joint arthrodesis. A significantly higher union rate was shown when arthrodesis was performed with highly porous β-TCP and BMAC, compared with arthrodesis performed without them. We suggest that highly porous β-TCP and BMAC can be a viable and effective adjunct to the fixation in midfoot joint arthrodesis.

LEVEL OF EVIDENCE

Level III: Retrospective comparative analysis.

Editorial Commentary: Autologous and Synthetic Bone Fillers for Medial Open-Wedge High Tibial Osteotomy Have No Effect on Clinical Outcomes But Autologous Graft Promotes Complete Bony Union

In contrast to closed-wedge high tibial osteotomy, medial based open-wedge high tibial osteotomy produces gaps of various sizes. Synthetic bone void fillers are an attractive option to close these gaps, potentially increase bone union, decrease time to union, and improve clinical outcomes. Autologous bone grafts are the accepted standard and result in reliable and reproducible outcomes. However, harvesting of autologous bone requires an additional procedure and is associated with potential complications. The use of synthetic bone void fillers could theoretically avoid these issues and reduce operating times. The current evidence suggests that autologous bone grafting has higher union rates but is not associated with better clinical and functional outcomes. Unfortunately, the certainty of evidence to support the use of bone void fillers is low, and the question of whether bone grafting of the gap should be performed in medial based open-wedge high tibial osteotomies cannot be answered with confidence.

Frontal sinus obliteration with beta-tricalcium phosphate putty: case series with long-term radiological follow up

OBJECTIVES

Frontal sinus obliteration is often performed using fat, autologous bone or a range of synthetic materials. This paper reports the long-term clinical and radiological outcomes of frontal sinus obliteration using beta-tricalcium phosphate putty.

METHODS

A retrospective audit was performed of patients who underwent frontal sinus obliteration with beta-tricalcium phosphate putty. Patient-, disease- and procedure-related data were collected. Pre- and post-operative computed tomography scans were reviewed to assess bone integration.

RESULTS

Four patients underwent frontal sinus obliteration using beta-tricalcium phosphate putty for treatment of a cerebrospinal leak, mucocele and recalcitrant frontal sinusitis. All patients had disease resolution, with no intra- or post-operative complications reported in the 16.5-month follow up. Post-operative computed tomography scans confirmed native bone obliteration of the frontonasal ducts in all patients.

CONCLUSION

Beta-tricalcium phosphate putty is a safe and effective option for bone obliteration of the frontal sinus in a range of pathologies, including cerebrospinal fluid leak.

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.

Characterization of bone remodeling of two different porous types of β-tricalcium phosphates: a quantitative site-by-site analysis using computed tomography

This study compared the process of bone remodeling using spherical porous β-tricalcium phosphate (SPTCP) and unidirectional porous β-tricalcium phosphate (UDPTCP) by quantitative computed tomography (CT) analysis. We retrospectively analyzed the data of 16 patients (4 men, 12 women; age, 43-78 years) who underwent medial opening wedge high tibial osteotomy (MOWHTO) and were followed up for 1 year postoperatively. Nine patients used SPTCP spacers and seven patients used UDPTCP spacers. CT was performed at 1 week, 6 months, and 1 year postoperatively. CT attenuation values were measured at three sites on the axial slice and sagittal slice, i.e., the superior, center, and inferior sites and the lateral, center, and medial sites for UDPTCP and SPTCP, respectively. CT attenuation values were lower for UDPTCP than for SPTCP in all sites at 6 months and 1 year postoperatively (p < 0.05). CT attenuation values decreased in the superior and inferior sites for UDPTCP (p < 0.05), and CT attenuation values decreased in the lateral site for both SPTCP and UDPTCP (p < 0.05). The process of bone remodeling differed between the two over a short-term follow-up of 1 year postoperatively.