Biomechanics of fracture healing: how best to optimize your construct in the OR.

Orthopaedic surgeons routinely assess the biomechanical environment of a fracture to create a fixation construct that provides the appropriate amount of stability in efforts to optimize fracture healing. Emerging concepts and technologies including reverse dynamization, "smart plates" that measure construct strain, and FractSim software that models fracture strain represent recent developments in optimizing construct biomechanics to accelerate bone healing and minimize construct failure.

Cadaveric Biomechanical Laboratory Research Can Be Quantitatively Scored for Quality With the Biomechanics Objective Basic Science Quality Assessment Tool: The BOBQAT Score.

PURPOSE: The purpose of this study was to develop a quality appraisal tool for the assessment of cadaveric biomechanical laboratory and other basic science biomechanical studies. METHODS: For item identification and development, a systematic review of the literature was performed. The content validity index (CVI) was used either to include or exclude items. The content validity ratio (CVR) was used to determine content validity. Weighting was performed by each panel member; the final weight was either up- or downgraded to the closest of 5% or 10%. Face validity was scored on a Likert scale ranked from 1 to 7. Test-retest reliability was determined using the Fleiss kappa coefficient. Internal consistency was assessed with Cronbach's alpha. Concurrent criterion validity was assessed against the Quality Appraisal for Cadaveric Studies scale. RESULTS: The final Biomechanics Objective Basic science Quality Assessment Tool (BOBQAT) score included 15 items and was shown to be valid, reliable, and consistent. Five items had a CVI of 1.0; 10 items had a CVI of 0.875. For weighting, 5 items received a weight of 10%, and 10 items a weight of 5%. CVR was 1.0 for 6 items and 0.75 for 9 items. For face validity, all items achieved a score above 5. For test-retest reliability, almost-perfect test-retest reliability was observed for 10 items, substantial agreement for 4 items, and moderate agreement for 1 item. For internal consistency, Cronbach's alpha was calculated to be 0.71. For concurrent criterion validity, Pearson's product-moment correlation was 0.56 (95% confidence interval [CI] = 0.38-0.70, P = .0001). CONCLUSION: Cadaveric biomechanical and laboratory research can be quantitatively scored for quality based on the inclusion of a clear and answerable purpose, demographics, specimen condition, appropriate bone density, reproducible technique, appropriate outcome measures, appropriate loading conditions, appropriate load magnitude, cyclic loading, sample size calculation, proper statistical analysis, results consistent with methods, limitations considered, conclusions based on results, and disclosure of funding and potential conflicts. CLINICAL RELEVANCE: Study quality assessments are important to evaluate internal and external validity and reliability and to identify methodological flaws and misleading conclusions. The BOBQAT score will help not only in the critical appraisal of cadaveric biomechanical studies but also in guiding the designs of such research endeavors.

Intramedullary implant stability affects patterns of fracture healing in mice with morphologically different bone phenotypes.

Almost all prior mouse fracture healing models have used needles or K-wires for fixation, unwittingly providing inadequate mechanical stability during the healing process. Our contention is that the reported outcomes have predominantly reflected this instability, rather than the impact of diverse biological conditions, pharmacologic interventions, exogenous growth factors, or genetic considerations. This important issue becomes obvious upon a critical review of the literature. Therefore, the primary aim of this study was to demonstrate the significance of mouse-specific implants designed to provide both axial and torsional stability (Screw and IM Nail) compared to conventional pins (Needle and K-wires), even when used in mice with differently sized marrow canals and diverse genetic backgrounds. B6 (large medullary canal), DBA, and C3H (smaller medullary canals) mice were employed, all of which have different bone morphologies. Closed femoral fractures were created and stabilized with intramedullary implants that provide different mechanical conditions during the healing process. The most important finding of this study was that appropriately designed mouse-specific implants, providing both axial and torsional stability, had the greatest influence on bone healing outcomes regardless of the different bone morphologies encountered. For instance, unstable implants in the B6 strain (largest medullary canal) resulted in significantly greater callus, with a fracture region mainly comprising trabecular bone along with the presence of cartilage 28 days after surgery. The DBA and C3H strains (with smaller medullary canals) instead formed significantly less callus, and only had a small amount of intracortical trabeculation remaining. Moreover, with more stable fracture fixation a higher BV/TV was observed and cortices were largely restored to their original dimensions and structure, indicating an accelerated healing and remodeling process. These observations reveal that the diaphyseal cortical thickness, influenced by the genetic background of each strain, played a pivotal role in determining the amount of bone formation in response to the fracture. These findings are highly important, indicating the rate and type of tissue formed is a direct result of mechanical instability, and this most likely would mask the true contribution of the tested genes, genetic backgrounds, or various therapeutic agents administered during the bone healing process.

Biomimetic Hematoma as a Novel Delivery Vehicle for rhBMP-2 to Potentiate the Healing of Nonunions and Bone Defects.

SUMMARY: The management of bone defects and nonunions creates unique clinical challenges. Current treatment alternatives are often insufficient and frequently require multiple surgeries. One promising option is bone morphogenetic protein-2 (BMP-2), which is the most potent inducer of osteogenesis. However, its use is associated with many side effects, related to the delivery and high doses necessary. To address this need, we developed an ex vivo biomimetic hematoma (BH), replicating naturally healing fracture hematoma, using whole blood and the natural coagulants calcium and thrombin. It is an autologous carrier able to deliver reduced doses of rhBMP-2 to enhance bone healing for complex fractures. More than 50 challenging cases involving recalcitrant nonunions and bone defects have already been treated using the BH delivering reduced doses of rhBMP-2, to evaluate both the safety and efficacy. Preliminary data suggest the BH is currently the only clinically used carrier able to effectively deliver reduced doses (∼70% less) of rhBMP-2 with high efficiency, rapidly and robustly initiating the bone repair cascade to successfully reconstruct complex bone injuries without side effects. The presented case provides a clear demonstration of this technology's ability to significantly alter the clinical outcome in extremely challenging scenarios where other treatment options have failed or are considered unsuitable. A favorable safety profile would portend considerable promise for BH as an alternative to bone grafts and substitutes. Although further studies regarding its clinical efficacy are still warranted, this novel approach nevertheless has tremendous potential as a favorable treatment option for bone defects, open fractures, and recalcitrant nonunions.

Reverse Dynamization Accelerates Regenerate Bone Formation and Remodeling in a Goat Distraction Osteogenesis Model.

UPDATE: This article was updated on December 20, 2023, because of previous errors, which were discovered after the preliminary version of the article was posted online. Figure 4 has been replaced with a figure that presents different p values. Also, on page 1943, the text that had read: "Quantitative microCT confirmed that the total volume of the regenerate in the RD group was much smaller compared with the SF (p = 0.06) and DF (p = 0.007) groups, although it was significantly smaller only compared with the DF group (Fig. 4-A). The total volume of the intact bone (contralateral tibia) was significantly smaller in the RD group compared with the other groups, but the RD group had values closest to those for the intact tibia. Similarly, the RD group had less bone volume compared with the SF and DF groups, and this value was significantly different from the DF group (p = 0.034; Fig. 4-B). Of the 3 groups, the RD group had vBMD that was the closest to that of intact bone. It also had significantly higher vBMD compared with the SF and DF groups (p < 0.0001 for both; Fig. 4-C).The results of torsional testing (Fig. 4-D) confirmed that the regenerate bone formed under conditions of RD was significantly stronger than that formed under SF or DF (p < 0.001 versus SF group, and p = 0.0493 versus DF group)."now reads: "Quantitative microCT confirmed that the total volume of the regenerate in the RD group was significantly smaller compared with the SF and DF groups (p < 0.01 for both groups; Fig. 4-A). The total volume of the intact bone (contralateral tibia) was significantly smaller compared with the SF and DF groups (p < 0.0001 for both). The RD group had values closest to those for the intact tibia, and this difference was not significant (Fig. 4-A). Similarly, the RD group had less bone volume compared with the SF and DF groups, and this value was significantly different from the DF group (p < 0.01; Fig. 4-B). Of the 3 groups, the RD group had vBMD that was the closest to that of intact bone, but the intact bone was significantly different compared with all of the other groups (p < 0.0001 for all groups). The RD group had significantly higher vBMD compared with the SF and DF groups (p = 0.042 and p = 0.046, respectively; Fig. 4-C).The results of torsional testing (Fig. 4-D) confirmed that the regenerate bone formed under conditions of RD was significantly stronger than that formed under SF or DF (p < 0.0001 versus SF group, and p = 0.0493 versus DF group). The intact group was significantly different compared with the SF group (p < 0.0001)."

The concept of reverse dynamization involves modifying the mechanical environment surrounding a fracture to influence the healing response. Initially, less rigid stabilization is performed to allow micromotion, encouraging cartilaginous callus formation. This is followed by a conversion to more rigid fixation to prevent the disruption of neovascularization, thereby accelerating bone healing and remodeling. The effect of reverse dynamization in distraction osteogenesis has not been studied, to our knowledge. The aim of this study was to determine whether reverse dynamization can accelerate the formation and maturation of regenerate bone in a goat distraction osteogenesis model. Midshaft tibial osteotomies were created in 18 goats and stabilized using circular external fixation. After a 5-day latency period, 4 weeks of limb distraction began to obtain a 2-cm gap; this was followed by 8 weeks of regenerate consolidation. The goats were divided into 3 groups: static (rigid) fixation (SF, n = 6); dynamic fixation (DF, n = 6), consisting of continuous micromotion using dynamizers; and reverse dynamization (RD, n = 6), consisting of initial micromotion during the distraction period using dynamizers followed by rigid fixation during the consolidation period. Healing was assessed using radiographs, micro-computed tomography, histological analysis, and mechanical testing. Radiographic evaluation showed earlier regenerate formation in the DF and RD groups compared with the SF group. After the distraction and consolidation periods were completed, the regenerate formed under the conditions of RD had less trabeculation, higher bone mineral density, and smaller total and bone volumes, and were stronger in torsion compared with the SF and DF groups. This appearance is characteristic of advanced remodeling, returning closest to the values of intact bone. The DF group also had evidence of an interzone (radiolucent fibrous zone) at the end of the consolidation period. Application of the reverse dynamization regimen during distraction osteogenesis accelerated formation, maturation, and remodeling of regenerate bone. The findings of this study have important implications in the clinical setting, as reverse dynamization may lead to shorter treatment times and potentially lower prevalence of complications for patients needing distraction osteogenesis.

Great debates in trauma biomechanics.

At the 2021 annual meeting of the Orthopaedic Trauma Association, the Basic Science Focus Forum hosted its first ever debate-style symposium focused on biomechanics and fracture repair. The 3 subjects of debate were "Mechanics versus Biology-Which is 'More Important' to Consider?" "Locked Plate versus Forward Dynamization versus Reverse Dynamization-Which Way Should I Go?" and "Sawbones versus Cadaver Models-What Should I Believe Most?" These debates were held because fracture healing is a highly organized synergistic response between biological factors and the local mechanical environment. Multiple studies have demonstrated that both factors play roles in governing bone healing responses, and the causal relationships between the 2 remain unclear. The lack of clarity in this space has led to a spectrum of research with the common goal of helping surgeons make good decisions. Before reading further, the reader should understand that the questions posed in the debate titles are unanswerable and might represent a false choice. Instead, the reader should appreciate that the debates were held to gain a more thorough understanding of these topics based on the current state of the art of experimental and clinical studies, by using an engaging and thought-provoking format.

Corticosteroid injections for the treatment of lateral epicondylitis are superior to platelet-rich plasma at 1 month but platelet-rich plasma is more effective at 6 months: an updated systematic review and meta-analysis of level 1 and 2 studies.

BACKGROUND: The purpose of this study was to perform a systematic review and meta-analysis of studies comparing local injections of either platelet-rich plasma (PRP) or corticosteroid for the treatment of lateral elbow epicondylitis. METHODS: A systematic review of MEDLINE, Embase, Scopus, and Google Scholar was performed, and all level 1 and 2 randomized studies from 2000 to 2022 were included. Clinical symptoms, patient perceived outcomes, and pain were assessed by the DASH (disabilities of the arm, shoulder and hand questionnaire) and pain by the visual analog scale (VAS). Publication bias and risk of bias were assessed using the Cochrane Collaboration's tools. The modified Coleman Methodology Score (CMS) and the GRADE system were used to assess the quality of the body of evidence. Heterogeneity was assessed using χ2 and I2 statistics. RESULTS: Thirteen studies were included in the analysis. Five studies had a high risk of bias, and the risk of bias across studies was assessed as unclear. There was no publication bias identified. Two of the four GRADE domains (inconsistency of results, imprecision of results) were downgraded to low quality, and the final GRADE assessment was downgraded to a low quality of evidence. The mean CMS score was 62.8, indicating fair quality. The pooled estimate for VAS at 1 month favored corticosteroids (P = .75) but favored PRP at three (P = .003) and six months (P = .0001). The pooled estimate for the DASH score favored corticosteroids at 1 month (P = .028) but favored PRP at three (P = .01) and six months (P = .107) CONCLUSION: The results of this meta-analysis suggest that PRP has no advantage over steroid injections within the first month of treatment, but that it is superior to steroids at both 3 and 6 months. These results also suggest that corticosteroids have a short-term beneficial effect during the early treatment period, although the quality of the available evidence is not very robust in support of this finding. However, these findings must all be viewed with caution as the high risk of bias and moderate to low quality of the included studies may not justify a recommendation of one treatment over another.

Biomimetic hematoma delivers an ultra-low dose of rhBMP-2 to successfully regenerate large femoral bone defects in rats.

Successful repair of large bone defects remains a clinical challenge. Following fractures, a bridging hematoma immediately forms as a crucial step that initiates bone healing. In larger bone defects the micro-architecture and biological properties of this hematoma are compromised, and spontaneous union cannot occur. To address this need, we developed an ex vivo Biomimetic Hematoma that resembles naturally healing fracture hematoma, using whole blood and the natural coagulants calcium and thrombin, as an autologous delivery vehicle for a very reduced dose of rhBMP-2. When implanted into a rat femoral large defect model, complete and consistent bone regeneration with superior bone quality was achieved with 10-20× less rhBMP-2 compared to that required with the collagen sponges currently used. Moreover, calcium and rhBMP-2 demonstrated a synergistic effect enhancing osteogenic differentiation, and fully restored mechanical strength 8 weeks after surgery. Collectively, these findings suggest the Biomimetic Hematoma provides a natural reservoir for rhBMP-2, and that retention of the protein within the scaffold rather than its sustained release might be responsible for more robust and rapid bone healing. Clinically, this new implant, using FDA-approved components, would not only reduce the risk of adverse events associated with BMPs, but also decrease treatment costs and nonunion rates.

Surgical treatment is not superior to nonoperative treatment for displaced proximal humerus fractures: a systematic review and meta-analysis.

BACKGROUND: The purpose of this study was to perform a systematic review and meta-analysis of both randomized controlled and observational studies comparing conservative to surgical treatment of displaced proximal humerus fractures. METHODS: We performed a systematic review of Medline, Embase, Scopus, and Google Scholar articles comparing surgical treatment to conservative treatment, including all level 1-3 studies from 2000 to 2022. Clinical outcome scores, range of motion, and complications were evaluated. Risk of bias was assessed using the Cochrane Collaboration's ROB2 tool and ROBINs-I tool. The GRADE system was used to assess the quality of the body of evidence, and heterogeneity was assessed using χ2 and I2 statistics. Twenty-two studies were incorporated into the analysis. Ten studies had a high risk of bias, and all included studies were of low quality. RESULTS: The pooled estimates failed to identify differences for clinical outcomes (P = .208), abduction (P = .275), forward flexion (P = .447), or external rotation (P = .696). Complication rates between groups were significantly lower (P = .00001) in the conservative group. CONCLUSIONS: This meta-analysis demonstrated that there were no statistically significant differences for either clinical outcomes or range of motion between surgically managed and conservatively treated displaced proximal humerus fractures. The overall complication rate was 3.3 times higher, following surgical treatment. The validity of this result is compromised by the high risk of bias and very low level of certainty of the included studies, and the conclusion must therefore be interpreted with caution.

Anterior cruciate ligament reconstruction results in better patient reported outcomes but has no advantage for activities of daily living or the subsequent development of osteoarthritis. A systematic review and meta-analysis.

BACKGROUND: Surgical reconstruction of ACL injuries is a common strategy but superiority over conservative treatment has not been established. The aim was to perform a systematic review and meta-analysis comparing outcomes between operative and non-operative treatment of ACL injuries. METHODS: Systematic review of Medline, Embase, Scopus, and Google Scholar, including all level 1-3 studies from 2000 to 2021. Patient reported outcome scores and objective measures for knee stability were included. Risk of bias was assessed using the Cochrane Collaboration's tools. GRADE was used to assess the quality of the body of evidence. Heterogeneity was assessed using χ2 and I2 statistics. RESULTS: Twelve studies were included in the analysis. All studies had a high risk of bias and were of low quality. The pooled estimates for IKDC (p = 0.040) favored surgical treatment. There were significant differences for activities of daily living (p = 0.0001) in favor of conservative treatment. There were significant differences for knee stability (p = 0.016) in favor of surgical treatment. The risk of osteoarthritis was not significantly different between the two treatment modalities (p = 0.219). Patients undergoing surgery had a 57% higher risk of osteoarthritis. CONCLUSION: ACL reconstruction results in a significantly more stable knee with superior clinical and functional outcomes. However, these advantages over conservative treatment were not observed for routine activities of daily living, and subjective patient perceived outcomes favor nonsurgical treatment. Surgical treatment did not reduce the risk of later developing osteoarthritis. Regardless, due to low study quality and high risk of bias, these findings must be interpreted with caution.

Surgical treatment of proximal humerus fractures: a systematic review and meta-analysis.

INTRODUCTION: The purpose of this study was to perform a systematic review and meta-analysis of both randomized controlled and observational studies comparing surgical interventions for proximal humerus fractures. METHODS: Systematic review of Medline, Embase, Scopus, and Google Scholar, including all level 1-3 studies from 2000 to 2022 comparing surgical treatment with ORIF, IM nailing, hemiarthroplasty, total and reverse shoulder arthroplasty (RTS) was conducted. Clinical outcome scores, range of motion (ROM), and complications were included. Risk of bias was assessed using the Cochrane Collaboration's ROB2 tool and ROBINs-I tool. The GRADE system was used to assess the overall quality of the body of evidence. Heterogeneity was assessed using χ2 and I2 statistics. RESULTS: Thirty-five studies were included in the analysis. Twenty-five studies had a high risk of bias and were of low and very low quality. Comparisons between ORIF and hemiarthroplasty favored ORIF for clinical outcomes (p = 0.0001), abduction (p = 0.002), flexion (p = 0.001), and external rotation (p = 0.007). Comparisons between ORIF and IM nailing were not significant for clinical outcomes (p = 0.0001) or ROM. Comparisons between ORIF and RTS were not significant for clinical outcomes (p = 0.0001) but favored RTS for flexion (p = 0.02) and external rotation (p = 0.02). Comparisons between hemiarthroplasty and RTS favored RTS for clinical outcomes (p = 0.0001), abduction (p = 0.0001), and flexion (p = 0.0001). Complication rates between groups were not significant for all comparisons. CONCLUSIONS: This meta-analysis for surgical treatment of proximal humerus fractures demonstrated that ORIF is superior to hemiarthroplasty, ORIF is comparable to IM nailing, reverse shoulder arthroplasty is superior to hemiarthroplasty but comparable to ORIF with similar clinical outcomes, ROM, and complication rates. However, the study validity is compromised by high risk of bias and low level of certainty. The results should therefore be interpreted with caution. Ultimately, shared decision making should reflect the fracture characteristics, bone quality, individual surgeon's experience, the patient's functional demands, and patient expectations. LEVEL OF EVIDENCE: Level III; systematic review and meta-analysis.

Fracture hematoma micro-architecture influences transcriptional profile and plays a crucial role in determining bone healing outcomes.

The hematoma that forms between broken fragments of bone serves as a natural fibrin scaffold, and its removal from the defect site delays bone healing. The hypothesis of this study is that the microarchitectural and mechanical properties of the initially formed hematoma has a significant effect on the regulation of the biological process, which ultimately determines the outcome of bone healing. To mimic three healing conditions in the rat femur (normal, delayed, and non-healing bone defects), three different defect sizes of 0.5, 1.5, and 5.0 mm, are respectively used. The analysis of 3-day-old hematomas demonstrates clear differences in fibrin clot micro-architecture in terms of fiber diameter, fiber density, and porosity of the formed fibrin network, which result in different mechanical properties (stiffness) of the hematoma in each model. Those differences directly affect the biological processes involved. Specifically, RNA-sequencing reveals almost 700 differentially expressed genes between normally healing and non-healing defects, including significantly up-regulated essential osteogenic genes in normally healing defects, also differences in immune cell populations, activated osteogenic transcriptional regulators as well as potential novel marker genes. Most importantly, this study demonstrates that the healing outcome has already been determined during the hematoma phase of bone healing, three days post-surgery.

Increased Posterior Slope of the Medial and Lateral Meniscus Posterior Horn Is Associated With Anterior Cruciate Ligament Injuries.

PURPOSE: To measure the slope of the medial and lateral posterior horn of the meniscus and its contribution to the overall resulting posterior tibial slope (bone and meniscus combined slope) in anterior cruciate ligament-intact (ACLI) and -deficient (ACLD) knees. METHODS: Magnetic resonance images of intact menisci in patients 16 to 60 years old were included. Posterior tibial bone slope (PTS) and meniscus slope (MS) were measured 25%, 50%, and 75% from the medial and lateral borders of the tibial plateau. Analysis of variance was used to determine differences in posterior tibial slopes between ACLD and ACLI knees and between sexes for ACLD and ACLI knees. RESULTS: 192 ACLI patients (age 35.2 ± 9.6 years, mean ± standard deviation) and 159 ACLD patients (age 34.2 ± 10.3 years) were included. Medial and lateral PTS in ACLD was significantly (P = .00001) higher at 25%, 50%, and 75%. Medial and lateral MS in ACLD was significantly (P = .00001) lower at 25%, 50%, and 75%. There were no significant sex differences for medial or lateral MS in ACLD or ACLI patients (P = .51). The resultant combined medial and lateral slope in ACLD patients was significantly (P = .00001) lower at 25%, 50%, and 75%. There were no significant sex differences in PTS (P = .68), MS (P = .51), or resultant slope (P = .79) CONCLUSIONS: The results of this study strongly suggest that lower meniscal slopes of both the medial and lateral posterior horns are associated with ACL injuries in both males and females. Although the posterior horns reversed the bone PTS to an anterior inclined slope in both ACLD and ACLI patients, both the meniscus slope and the combined resultant slope were significantly lower and more positive at all 6 measured locations in ACLD knees. LEVEL OF EVIDENCE: III, retrospective cohort study.

Subacromial Decompression in Patients With Shoulder Impingement With an Intact Rotator Cuff: An Expert Consensus Statement Using the Modified Delphi Technique Comparing North American to European Shoulder Surgeons.

PURPOSE: To perform a Delphi consensus for the treatment of patients with shoulder impingement with intact rotator cuff tendons, comparing North American with European shoulder surgeon preferences. METHODS: Nineteen surgeons from North America (North American panel [NAP]) and 18 surgeons from Europe (European panel [EP]) agreed to participate and answered 10 open-ended questions in rounds 1 and 2. The results of the first 2 rounds were used to develop a Likert-style questionnaire for round 3. If agreement at round 3 was ≤60% for an item, the results were carried forward into round 4. For round 4, the panel members outside consensus (>60%, <80%) were contacted and asked to review their response. The level of agreement and consensus was defined as 80%. RESULTS: There was agreement on the following items: impingement is a clinical diagnosis; a combination of clinical tests should be used; other pain generators must be excluded; radiographs must be part of the workup; magnetic resonance imaging is helpful; the first line of treatment should always be physiotherapy; a corticosteroid injection is helpful in reducing symptoms; indication for surgery is failure of nonoperative treatment for a minimum of 6 months. The NAP was likely to routinely prescribe nonsteroidal anti-inflammatory drugs (NAP 89%; EP 35%) and consider steroids for impingement (NAP 89%; EP 65%). CONCLUSIONS: Consensus was achieved for 16 of the 71 Likert items: impingement is a clinical diagnosis and a combination of clinical tests should be used. The first line of treatment should always be physiotherapy, and a corticosteroid injection can be helpful in reducing symptoms. The indication for surgery is failure of no-operative treatment for a minimum of 6 months. The panel also agreed that subacromial decompression is a good choice for shoulder impingement if there is evidence of mechanical impingement with pain not responding to nonsurgical measures. LEVEL OF EVIDENCE: Level V, expert opinion.

Biomechanical Studies for Glenoid Based Labral Repairs With Suture Anchors Do Not Use Consistent Testing Methods: A Critical Systematic Review.

PURPOSE: The purpose of this systematic review was to investigate variability in biomechanical testing protocols for laboratory-based studies using suture anchors for glenohumeral shoulder instability and SLAP lesion repair. METHODS: A systematic review of Medline, Embase, Scopus, and Google Scholar using Covidence software was performed for all biomechanical studies investigating labral-based suture anchor repair for shoulder instability and SLAP lesions. Clinical studies, technical notes or surgical technique descriptions, or studies treating glenoid bone loss or capsulorrhaphy were excluded. Risk of bias (ROB) was assessed with the ROBINS-I tool. Study quality was assessed with the Quality Appraisal for Cadaveric Studies. Heterogeneity was assessed with the I2 statistic. RESULTS: A total of 41 studies were included. ROB was serious and critical in 27 studies, moderate in 13, and low in 1; 6 studies had high quality, 21 good quality, 10 moderate quality, 2 low quality, and 2 very low quality. Thirty-one studies used and 22 studies included cyclic loading. Angle of anchor insertion was reported by 33 studies. The force vector for displacement varied. The most common directions were perpendicular to the glenoid (n = 9), and anteroinferior or anterior (n = 8). The most common outcome measures were load to failure (n = 35), failure mode (n = 23), and stiffness (n = 21). Other outcome measures included load at displacement, displacement at failure, tensile load at displacement, translation, energy absorbed, cycles to failure, contact pressure, and elongation. CONCLUSION: This systematic review demonstrated a clear lack of consistency in those cadaver studies that investigated biomechanical properties after surgical repair with suture anchors for shoulder instability and SLAP lesions. Testing methods between studies varied substantially with no universally applied standard for preloading, load to failure and cyclic loading protocols, insertion angles of suture anchors, or direction of loading. To allow comparability between studies standardization of testing protocols is strongly recommended.

Three-stage limb salvage in tibial fracture related infection with composite bone and soft-tissue defect.

INTRODUCTION: Managing critical-sized tibial defects is one of the most complex challenges orthopedic surgeons face. This is even more problematic in the presence of infection and soft-tissue loss. The purpose of this study is to describe a comprehensive three-stage surgical protocol for the reconstruction of infected tibial injuries with combined bone defects and soft-tissue loss, and report the clinical outcomes. MATERIALS AND METHODS: A retrospective study at a specialized limb reconstruction center identified all patients with infected tibial injuries with bone and soft-tissue loss from 2010 through 2018. Thirty-one patients were included. All cases were treated using a three-stage protocol: (1) infected limb damage control; (2) soft-tissue coverage with a vascularized or local flap; (3) definitive bone reconstruction using distraction osteogenesis principles with external fixation. PRIMARY OUTCOMES: limb salvage rate and infection eradication. SECONDARY OUTCOMES: patient functional outcomes and satisfaction. RESULTS: Patients in this series of chronically infected tibias had been operated upon 3.4 times on average before starting our limb salvage protocol. The mean soft-tissue and bone defect sizes were 124 cm2 (6-600) and 5.4 cm (1-23), respectively. A free flap was performed in 67.7% (21/31) of the cases; bone transport was the selected bone-reconstructive option in 51.7% (15/31). Local flap failure rate was 30% (3/10), with 9.5% for free flaps (2/21). Limb salvage rate was 93.5% (29/31), with infection eradicated in all salvaged limbs. ASAMI bone score: 100% good/excellent. Mean VAS score was 1.0, and ASAMI functional score was good/excellent in 86% of cases. Return-to-work rate was 83%; 86% were "very satisfied" with the treatment outcome. CONCLUSION: A three-stage surgical approach to treat chronically infected tibial injuries with combined bone and soft-tissue defects yields high rates of infection eradication and successful limb salvage, with favorable functional outcomes and patient satisfaction.

Medial and Lateral Posterior Tibial Slope Are Independent Risk Factors for Noncontact ACL Injury in Both Men and Women.

BACKGROUND: Higher posterior tibial slope (PTS) is a risk factor for anterior cruciate ligament (ACL) injury in men and women. The individual contribution of the lateral (LPTS) and medial (MPTS) slope has not yet been investigated. PURPOSE: To determine whether either the LPTS or the MPTS is an independent risk factor for ACL injury, and to determine sex-specific differences between patients with ACL-deficient and ACL-intact knees. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: We reviewed knee magnetic resonance (MR) images performed on ACL-deficient and ACL-intact knees between January 2018 and June 2020 at a single institution. Inclusion criteria were isolated ACL injury and noncontact mechanism (ACL-deficient group) and nonspecific knee pain and no history of injury (ACL-intact group). Exclusion criteria for both groups were the following: previous knee surgery; meniscal, collateral ligament, posterior cruciate ligament, or multiligamentous injuries; radiological evidence of osteoarthritis; and chondral damage on the tibia. The MR images were used to establish the posterior bony slope at 25%, 50%, and 75% from the medial and/or lateral border of the tibial plateau with respect to the proximal tibial anatomic axis. One-way analysis of variance (ANOVA) was used to determine differences in PTS at the 25%, 50%, and 75% distances for the medial and lateral tibial plateau between the groups and between the sexes. RESULTS: Overall, 325 images were included (mean age, 36.1 ± 11.1 years; 142 ACL-deficient images [82 men and 60 women]; 183 ACL-intact images [112 men and 71 women]). MPTS and LPTS were significantly higher at 25%, 50%, and 75% in the ACL-deficient group (range, -2.7° to -5.7°) compared with the ACL-intact group (range, -2.1° to 1.5°; P = .00001). Similarly, MPTS and LPTS were significantly different in men versus women (P = .00001). ANOVA revealed that there were no significant differences in PTS between men and women for all measures (MPTS, LPTS, ACL-deficient, ACL-intact; P = .68). CONCLUSION: The study results demonstrated that higher MPTS and LPTS is a potential risk factor for ACL injury in both men and women. However, despite being highly statistically significant, the differences between groups and sexes were small and may not be clinically relevant.

Treatment with a long-acting chimeric CSF1 molecule enhances fracture healing of healthy and osteoporotic bones.

Macrophage-targeted therapies, including macrophage colony-stimulating factor 1 (CSF1), have been shown to have pro-repair impacts post-fracture. Preclinical/clinical applications of CSF1 have been expedited by development of chimeric CSF1-Fc which has extended circulating half-life. Here, we used mouse models to investigate the bone regenerative potential of CSF1-Fc in healthy and osteoporotic fracture. We also explored whether combination of CSF1-Fc with interleukin (IL)-4 provided additional fracture healing benefit in osteopenic bone. Micro-computed tomography, in situ histomorphometry, and bone mechanical parameters were used to assess systemic impacts of CSF1-Fc therapy in naive mice (male and female young, adult and geriatric). An intermittent CSF1-Fc regimen was optimized to mitigate undesirable impacts on bone resorption and hepatosplenomegaly, irrespective of age or gender. The intermittent CSF1-Fc regimen was tested in a mid-diaphyseal femoral fracture model in healthy bones with treatment initiated 1-day post-fracture. Weekly CSF1-Fc did not impact osteoclasts but increased osteal macrophages and improved fracture strength. Importantly, this treatment regimen also improved fracture union and strength in an ovariectomy-model of delayed fracture repair. Combining CSF1-Fc with IL-4 initiated 1-week post-fracture reduced the efficacy of CSF1-Fc. This study describes a novel strategy to specifically achieve bone regenerative actions of CSF1-Fc that has the potential to alleviate fragility fracture morbidity and mortality.