Citations

Abstract Preiser's disease (PD), or idiopathic avascular necrosis of the scaphoid, is a debilitating condition leading to wrist pain, dysfunction, and pan-carpal arthritis. While impaired scaphoid vascularity is central to its pathogenesis, identifying individuals at risk is challenging due to the morphological distortion of the scaphoid as the disease progresses. This study aims to investigate the association between a novel capitate morphology classification, scaphoid morphology, and their impact on PD prevalence and characteristics. We also re-evaluate negative ulnar variance (NUV) as a potential risk factor for PD. This retrospective case–control study included 34 PD patients and 340 age-matched controls. Capitate morphology was classified into Type I/II on anteroposterior (AP) radiographs based on capitotrapezoid–scaphocapitate (CT–SC) joint line angle and ratio. Scaphoid morphology was assessed via the waist index on contralateral healthy wrists. Radiographic measurements of ulnar variance and PD staging were also performed. Statistical analyses compared morphological prevalence and risk factors between groups. Type II capitate was significantly more prevalent in the PD group (35.3%) than in controls (17.1%, p = 0.018). Similarly, NUV was significantly higher in PD patients (29%) compared with controls (6.8%, p < 0.001). We found a strong correlation between Type II capitate and slender (Type II) scaphoid morphology in healthy wrists. No significant differences in age, gender, or affected side were observed. Interobserver and intraobserver agreements for capitate classification were substantial (kappa ≥0.882). Our study introduces a reliable radiographic method for classifying capitate morphology, which strongly correlates with intrinsic scaphoid shape and potential vascular vulnerability. Both Type II capitate morphology and NUV are significant predisposing factors for PD. These findings offer valuable insights for identifying at-risk individuals and improving understanding of PD's multifactorial etiology. Diagnostic Level III.

Background: The authors present a novel microsurgical model to investigate ischemia-reperfusion (I/R) injury in composite tissue (muscle/skin) using a musculocutaneous flap. I/R was induced in a rodent biceps femoris musculocutaneous flap through collateral ligation and arteriovenous clamping. The authors hypothesized that I/R flaps would show greater tissue damage compared with sham. Methods: Male rats were randomized into I/R ( n = 10) and sham ( n = 9) groups. The I/R group underwent flap elevation, collateral ligation, 3 hours of arteriovenous clamping, followed by reperfusion. The sham group had flap elevation only. Perfusion was monitored using laser-speckle imaging, and flap discoloration was assessed with blinded skin ischemia necrosis scores. Serum and the composite tissue (skin/muscle) were analyzed for injury on postoperative days (PODs) 1 or 3. Results: Clamping reduced perfusion ( P = 0.00), whereas unclamping increased perfusion ( P <0.00). Over time, flaps exposed to I/R were more ischemic (estimate, 0.39; P = 0.02). At POD1, the injury group had higher serum creatine kinase ( P = 0.04) and potassium ( P = 0.00) than the sham group. The injury group had more muscle apoptosis (34.7% versus 5.2%; P = 0.03), myonecrosis (30.3% versus 14.1%; P = 0.04), and inflammation (13.7% versus 4.9%; P = 0.02) than the sham group; myonecrosis and inflammation persisted into POD3. Skin apoptosis and inflammation were similar. Conclusions: This model reliably reproduces I/R injury with a 3-hour ischemic period followed by early reperfusion. Animals subjected to the authors’ technique showed greater tissue damage than the sham group, with muscle being more vulnerable than skin. Serum showed peak muscle injury at 24 hours, and histologic analysis showed myonecrosis and inflammation through 72 hours. This suggests that less than 24 hours’ reperfusion (eg, critical window) may serve as the optimal time for possible intervention. Clinical Relevance Statement: I/R injury is a complex phenomenon affecting vascular composite tissues. The mitochondrial superoxide dismutase may be more specific for I/R injury. There may be a critical window within which to mitigate injury (<24 hours after reperfusion). The authors’ model helps investigate muscle/skin I/R injury.

AimsPrevious studies have highlighted differences in the risk of periprosthetic fractures (PPFs) in patients undergoing total hip arthroplasty with either a cemented taper slip (TS) stem or a composite beam (CB) stem. This biomechanical study explored the occurrence of PPF around these stems, and the protective effect of adding a 16-gauge prophylactic calcar or diaphyseal wire to the TS stems to increase the resistance to torque as a potential way to prevent these fractures.MethodsA total of 21 TS stems (eight alone, six with calcar wiring, and seven with diaphyseal wiring placed 2 cm distal to the lesser trochanter) and seven CB stems were cemented into standard sawbones. The peak torque at failure was measured using a servohydraulic test machine, and the fracture location was recorded. An a priori power analysis determined that seven specimens per group were needed to detect a 30 Nm difference with 90% power, assuming a 14.8 Nm SD in peak torque between groups. Comparisons were performed using paired t-tests.ResultsCB stems exhibited a significantly higher mean peak torque at failure (205.3 Nm (SD 26.9)) than TS stems (159.5 Nm (SD 17.4); p = 0.012), calcar-wired TS (148.2 Nm (SD 38.6); p = 0.031), and diaphyseal-wired TS (164.9 Nm (SD 21.5); p = 0.027). This study did not demonstrate that wired-TS stems had a higher peak torque at failure than non-wired TS stems. Additionally, calcar wiring was not found to be stronger than diaphyseal wiring (p = 0.400). Four CB fractures occurred distal to the stem, whereas all TS fractures occurred at the mid-stem, simulating a Vancouver type B fracture. Interestingly, adding the diaphyseal wire shifted the fracture location more distally in four of the seven stems (p = 0.070).ConclusionIn this model, CB stems had greater resistance to torque than TS stems, which may explain the lower risk of PPF. Adding calcar or diaphyseal wires to the TS stems resulted in no significant change in peak torque to fracture. CB cemented stems should be considered in patients at high risk of PPF.Cite this article: Bone Joint J 2025;107-B(5 Supple A):32–37.

Abstract Rhabdomyolysis following revascularization of the ischemic upper extremity can lead to life- & limb- threatening sequelae. In the context of replantations and vascularized composite allografting, a reconstructive procedure usually reserved for upper limb amputees, prolonged tissue ischemia is detrimental to extremity functional recovery. Currently, validated survival small animal models of extremity reperfusion injury that permit longitudinal assessment of limb function are lacking. To date, studies that evaluated reperfusion injury-induced neuromuscular impairment rely on terminal ex vivo procedures and do not provide clinically translatable measurements. Furthermore, it is unclear if upper extremity musculature exhibits a different ischemic threshold compared to the lower limb given the relatively rare incidence of upper limb ischemia. Here, we present a reliable rat model of extremity post-reperfusion syndrome (PRS) that comprehensively recapitulates the biochemical hallmarks of rhabdomyolysis secondary to upper extremity reperfusion injury and allows for monitoring in vivo upper limb function using clinically relevant electrodiagnostic and kinematic metrics. In addition to inducing severe metabolic derangements, our forelimb PRS provided insights on gross motor and electrophysiological alterations upper extremity reperfusion injury. We identify gait coordination parameters such as stride frequency and forelimb-hindlimb coordination index and electrophysiological metrics including compound muscle action potential amplitude as objective, non-invasive outcome measures for limb function assessment in small animal models of extremity PRS. This comprehensive, validated functional model can serve as an invaluable tool to evaluate therapeutics or preconditioning regimens to attenuate PRS and mitigate resulting neuromuscular dysfunction.

Muscle stem cells (MuSCs) are essential for skeletal muscle regeneration, influenced by a complex interplay of mechanical, biochemical, and molecular cues. Properties of the extracellular matrix (ECM) such as stiffness and alignment guide stem cell fate through mechanosensitive pathways, where forces like shear stress translate into biochemical signals, affecting cell behavior. Aging introduces senescence which disrupts the MuSC niche, leading to reduced regenerative capacity via epigenetic alterations and metabolic shifts. Transplantation further challenges MuSC viability, often resulting in fibrosis driven by dysregulated fibro-adipogenic progenitors (FAPs). Addressing these issues, scaffold designs integrated with pharmacotherapy emulate ECM environments, providing cues that enhance graft functionality and endurance. These scaffolds facilitate the synergy between mechanotransduction and intracellular signaling, optimizing MuSC proliferation and differentiation. Innovations utilizing human pluripotent stem cell-derived myogenic progenitors and exosome-mediated delivery exploit bioactive properties for targeted repair. Additionally, 3D-printed and electrospun scaffolds with adjustable biomechanical traits tackle scalability in treating volumetric muscle loss. Advanced techniques like single-cell RNA sequencing and high-resolution imaging unravel muscle repair mechanisms, offering precise mapping of cellular interactions. Collectively, this interdisciplinary approach fortifies tissue graft durability and MuSC maintenance, propelling therapeutic strategies for muscle injuries and degenerative diseases.

Abstract: In knee arthroscopy procedures, maintaining the opening of the medial compartment requires an assistant. Creating the posterior portal in knee arthroscopy is also a challenge because of the shape changes of the thick muscle. The leg is usually placed on the surgical bed, is angled off the lateral aspect of the bed, or drapes over the surgical bed in which the leg plates are removed. However, the aforementioned positions have some limits because of surgical convenience and procedural stability. In this Technical Note, we propose an approach to improve the existing knee positions using a metal round stool as a foot support. The method aims to reduce reliance on human assistants during knee arthroscopy procedures and restore the natural positioning of leg muscles, potentially improving procedural outcomes. Technique Video video See video under supplementary data.

Background: Rotator cuff repair augmentation using biological materials has become popular in clinical practice to reduce the high retear rates associated with traditional repair techniques. Tissue engineering approaches, such as engineered tendon-fibrocartilage-bone composite (TFBC), have shown promise in enhancing the biological healing of rotator cuff tears in animals. However, previous studies have provided limited long-term data on TFBC repair outcomes. The effect of mechanical stimulation on TFBC has not been explored extensively. Purpose: To evaluate functional outcomes after rotator cuff repair with engineered TFBC subjected to mechanical stimulation in a 6-month follow-up using a canine in vivo model. Study Design: Controlled laboratory study. Methods: A total of 40 canines with an acute infraspinatus (ISP) tendon transection model were randomly allocated to 4 groups (n =10): (1) unilateral ISP tendon undergoing suture repair only (control surgery); (2) augmentation with engineered TFBC alone (TFBC); (3) augmentation with engineered TFBC and bone marrow-derived stem cells (BMSCs) (TFBC+C); and (4) augmentation with engineered TFBC and BMSCs, as well as mechanical stimulation (TFBC+C+M). Outcome measures—including biomechanical evaluations such as failure strength, stiffness, failure mode, gross appearance, ISP tendon and muscle morphological assessment, and histological analysis—were performed 6 months after surgery. Results: As shown in the mechanical test, the TFBC+C+M group exhibited higher failure strength compared with other repair techniques. The most common failure mode was avulsion fracture in the TFBC+C+M group, but tendon-bone junction rupture was observed predominantly in different groups. Engineered TFBC with mechanical stimulation showed over 70% relative failure strength compared with normal ISP, and the other groups showed about 50% relative failure strength. Histological analysis revealed less fat infiltration and closer-to-normal muscle fiber structure in the mechanical stimulation group. Conclusion: This study provides evidence that mechanical stimulation of engineered TFBC promotes rotator cuff regeneration, thus supporting its potential for rotator cuff repair augmentation. Clinical Relevance: This study provides valuable evidence supporting the use of a novel tissue-engineered material (TFBC) in rotator cuff repair and paves the way for advancements in the field of rotator cuff regeneration.

Abstract The significance of anterior cruciate ligament (ACL) remnants during reconstruction remains unclear. Co‐culturing ACL remnant cells and bone marrow stromal cells (BMSCs) may reduce apoptosis and enhance hamstring tendon activity. This study investigated whether extracellular vesicles (EVs), which facilitate cell–cell interactions, act as the active components, improving graft maturation in this co‐culture. The effects of EVs on cell viability, proliferation, migration and gene expression in the rabbit ACL remnant cells and BMSCs were assessed using control (BMSC‐only culture), co‐culture (ACL remnant cells and BMSCs, CM) and co‐culture without EVs (CM ∆ EVs) media. EVs were isolated from control (BMSC‐EV) and co‐culture (CM‐EV) media and characterized. CM significantly enhanced the proliferation, migration and expression of transforming growth factor ( TGF‐β )‐, vascular endothelial growth factor ( VEGF )‐, collagen synthesis‐ and tenogenesis‐related genes. However, CM‐induced effects were reversed by the CM ∆ EVs treatment. CM‐EV treatment exhibited higher potential to enhance proliferation, migration and gene expression in the ACL remnant cells and BMSCs than BMSC‐EV and non‐EV treatments. In conclusion, EVs, secreted under the coexistence of ACL remnant cells and BMSCs, primarily increase the cell viability, proliferation, migration and gene expression of collagen synthesis‐, TGF‐β ‐, VEGF ‐ and tenogenesis‐related genes in both cell types.

Previous studies have highlighted differences in the risk of periprosthetic fracture between tapered slip (TS) and composite beam (CB) stems. This biomechanical study explored periprosthetic fractures around these stems and the effect of adding a 16-gauge calcar or diaphyseal wire to TS stems on their resistance to torque.A power analysis determined a sample size of 7 specimens per group, assuming a standard deviation of 14.8 Nm in peak torque, to provide 90% power to detect a difference of at least 30 Nm between groups. Twenty-one TS stems (eight alone, six with calcar wiring, seven with diaphyseal wiring placed 2 cm distal to the lesser trochanter) and seven CB stems were cemented into standard Sawbones. A servo-hydraulic test machine applied a 1000 N load with a 1-degree rotation per second until failure. The peak torque at failure was measured, and the fracture location recorded. Comparisons were performed using two-sample t-tests.CB stems exhibited a significantly higher peak torque at failure (205.3 Nm) than TS stems (159.5 Nm, p=0.020). Calcar-wire-TS (148.2 Nm, p=0.036) and diaphyseal-wire-TS (164.9 Nm, p=0.036) were both weaker than CB stems. Wired-TS stems showed no significant difference from non-wired-TS stems. Additionally, the study could not conclude that calcar wiring is stronger than diaphyseal wiring. All TS fractures occurred at the mid-stem, simulating a B-type fracture, while the addition of the diaphyseal wire shifted the fracture location more distally in four of seven stems (p=0.0699).This biomechanical study supports the clinical evidence that CB stems have stronger resistance to torque than TS stems and may explain lower risk of periprosthetic fracture. The addition of calcar or diaphyseal wires to TS stems resulted in no significant changes in peak torque to fracture. In patients at high risk of periprosthetic fracture, CB cemented stems should be considered.

Abstract Flexor tendon injury is a common hand trauma that requires surgical repair. The objective was to compare the repaired strength and gliding resistance with a varied number of repair strands and of square knots using a two‐strand‐overhand locking (TSOL) knot. First, isolated suture loops with different number of suture strands and number of closing knots were compared in mechanical strength and failure mode. Then, 90 flexor digitorum profundus (FDP) tendons from turkey digits were used for the tendon repair experiment. Both phases followed a similar 3 × 3 matrix comparing the knot type including TSOL+1SK (square knot), TSOL+2SK, and TSOL+3 SK and repair techniques including two‐, four‐, and six‐strand repairs techniques respectively. The repaired tendons were tested for tendon resistance against pulley (friction), maximum force, force at 2 mm displacement, stiffness, and failure mode. Increasing the number of strands and closing square knots increases the tensile strength and stiffness of flexor tendon repairs and isolated suture loops without a significant effect on tendon friction. An increase in the number of square knots have shown increased strength only in Pennington repair, which correlated with the increased number of knot unraveling, a weak knot failure model. Our data demonstrated that increasing the number of strands is effective for improving the overall strength of tendon repair. When a two‐strand repair is chosen, increasing knot number can improve repair strength. However, the number of knots appears not affecting repair strength in six‐strand repair technique.