Unicortical Versus Bicortical Proximal Locking Screw for Prevention of Peri-Implant Fracture: A Biomechanical Analysis of an Osteoporotic Distal Radius Model.

Purpose: Osteoporotic patients are at risk of peri-implant fractures after distal radius fixation. A unicortical screw in the proximal hole of the plate can theoretically decrease stress riser formation by eliminating the hole in the far bone cortex. This construct has been proposed in orthopedic literature to prevent peri-implant fractures but has not been tested in an osteoporotic distal radius model.

The Effect of Forearm Shortening on Finger Flexion: A Biomechanical Study.

Purpose: Surgeons may shorten the forearm for many indications. We quantified the impact of shortening on finger flexion with a cadaver model.

Methods: Ten fresh cadaver proximal forearms were pinned to a static block.

Perilunate Dislocations: Cadaveric Model K-Wire Versus Compression Staple Fixation.

Purpose: Repair of perilunate dislocations requires stabilization of the carpal bones, although there is limited research on the preferred method(s) of stabilization. We compared the biomechanical characteristics of K-wire versus staple fixation of scapholunate (SL) and lunotriquetral (LT) intervals in the wrist.

Methods: After creating a grade IV instability model, 20 cadaver wrists were randomized into 2 stabilization model groups using K-wires or surgical staples across the SL and LT intervals.

Biomechanics of subscapularis V-shaped tenotomy compared to standard tenotomy.

Background: Subscapularis function is critical after anatomic total shoulder arthroplasty (aTSA). Recently, however, a technique has been described that features a chevron or V-shaped subscapularis tendon cut (VT). This biomechanical study compared repair of the standard tenotomy (ST), made perpendicular to the subscapularis fibers, to repair of the novel VT using cyclic displacement, creep, construct stiffness, and load to failure.

How many anchors to use in arthroscopic Bankart repairs? A biomechanical study of postage-stamp glenoid fractures.

Background: Deciding how many anchors to use in a Bankart repair is challenging because of the desire to enhance stability while avoiding a postage-stamp fracture of the glenoid rim.

Methods: This controlled laboratory study investigated load to fracture of the anterior glenoid rim after drilling holes of varying number and diameter and inserting anchors of 2 different types and sizes, with and without perforation of the medial cortex of the glenoid, creating postage-stamp fractures using a metallic humeral head that was compressed against the anterior glenoid rim. A destructive model with a servohydraulic load frame was used to test 46 synthetic scapulae with compressive strength and elastic modulus similar to that of a human glenoid.

Effect of reverse shoulder arthroplasty humeral component retroversion on acromial strain.

Introduction: Acromion and scapular spine stress fractures can be catastrophic complications following reverse shoulder arthroplasty (RSA). A variety of host, implant, and technical factors have been identified that increase the risk of this complication. The glenoid component in particular has been closely evaluated for its impact on rates of stress fractures following RSA.

Effect of glenosphere lateralization with and without coracoacromial ligament transection on acromial and scapular spine strain in reverse shoulder arthroplasty.

Background: Small changes in deltoid tension and moment arm due to glenosphere lateralization may be associated with an increase in acromion or scapular spine strain in reverse shoulder arthroplasty (RSA), which can lead to stress fracture. The coracoacromial ligament (CAL) may be protective and lower the strain seen on the acromion or scapular spine. This biomechanical study investigated the impact of glenosphere lateralization and CAL integrity on acromion and scapular spine strain after RSA.

Impact of radiocapitellar interposition arthroplasty on ulnohumeral joint biomechanics.

Background: Radial head excision (RHE) has been shown to increase contact pressures within the ulnohumeral joint. Radiocapitellar interposition arthroplasty (RCIA) with the use of a soft tissue graft is an alternative for the treatment of isolated radiocapitellar arthritis or with failure of radial head replacement. We investigated contact pressures and contact area within the ulnohumeral joint after RHE compared to RCIA with dermal autograft.

Effect of Poly-L-Lactic Acid Mesh Augmentation on Cyclic Gap Formation in Transosseous Patellar Tendon Repair: A Biomechanical Study.

No previous study has investigated poly-L-lactic acid (PLLA) surgical mesh augmentation in the repair of inferior pole patellar tendon rupture. We compared the biomechanical properties of transosseous patellar tendon repair with PLLA surgical mesh augmentation to transosseous repair without augmentation. Ten matched pairs of cadaveric knees were used.

All-Suture Anchor Repair of the Flexor Digitorum Profundus Insertion: A Biomechanical Comparison of 2 Suturing Techniques.

Purpose: We compared 2 suturing techniques for reattachment of the flexor digitorum profundus (FDP) via all-suture anchor.

Methods: We used fresh, matched-pair, cadaveric hands. We disarticulated the fingers at the proximal interphalangeal joints, preserving the proximal FDP.

Comparison of 3 Dynamic External Fixation Devices for Proximal Interphalangeal Joint Dorsal Fracture-Dislocations in a Cadaver Model.

Purpose: Several improvised dynamic external fixation devices are used for treating unstable dorsal proximal interphalangeal (PIP) joint fracture-dislocations. We compared the effectiveness of 3 constructs for simulated dorsal PIP joint fracture-dislocations in a cadaver model.

Methods: We tested 30 digits from 10 fresh-frozen, thawed cadaver hands.

Effect of Lateral Retinacular Release on Medial Patellofemoral Ligament Reconstruction.

Background: When performing a medial patellofemoral ligament (MPFL) reconstruction, surgeons may place the MPFL graft under higher than anatomic tension to minimize the chance of recurrent instability.

Purpose: To investigate whether a lateral retinacular release (LRR) significantly decreases patellofemoral contact pressures after an overtensioned (OT) MPFL reconstruction.

Study Design: Controlled laboratory study.

Weightbearing after combined medial and lateral plate fixation of AO/OTA 41-C2 bicondylar tibial plateau fractures: a biomechanical study.

Background: Combined medial and lateral plate fixation is recommended for complex tibial plateau fractures with medial fragments or no cortical bone contact. Although such fixation is adequate to resist forces during range of motion, it may be insufficient to support immediate postoperative weightbearing. Here, we analyzed displacement, stiffness, and fixation failure during simulated full weightbearing of bicondylar tibial plateau fractures treated with combined medial and lateral locking plate fixation.

Long head of biceps transfer to augment Bankart repair in chronic anterior shoulder instability with and without subcritical bone loss: a biomechanical study.

Background: Treating recurrent anterior shoulder instability in participants in collision sports, patients with capsulolabral defects, and patients with bipolar bone loss remains challenging. The study purpose was to investigate the effect of long head of the biceps transfer (LHBT) on load-to-dislocation biomechanics in a repetitive serial shoulder dislocation cadaveric model comparing LHBT with the Latarjet and Bankart procedures-the first-line treatment methods for chronic traumatic anterior shoulder instability with and without anterior glenoid bone loss, respectively.

Methods: In this controlled laboratory study, 8 fresh-frozen cadaveric shoulders with different conditions were dislocated in sequence using a custom test frame.

The Impact of Dividing the Flexor Tendon Pulleys on Tendon Excursion and Work of Flexion in a Cadaveric Model.

Purpose: The A2 and A4 pulleys of the flexor tendon system have traditionally been considered critical components of efficient digital flexion. This dogma has recently been challenged. Using fresh human cadaveric hands and a model to measure force and excursion, we sought to clarify the clinical importance of releasing different pulleys.

Biomechanical comparison of zoned-conformity glenoid versus standard glenoid in total shoulder arthroplasty: impact on rotator cuff strain and glenohumeral translation.

Background: Current standard total shoulder arthroplasty glenoid implants allow for high levels of glenohumeral mismatch and associated high levels of humeral head translation to improve range of motion and reduce rim stresses on the glenoid. However, high levels of glenohumeral mismatch could also increase glenoid edge loading, eccentric wear, and rotator cuff strain. A zoned-conformity glenoid may be able to reduce the forces on the rotator cuff and glenoid.

Adjustable Cortical Fixation Device for Quadriceps Tendon Repair: A Cadaveric Biomechanical Study.

Background: Adjustable cortical fixation devices have demonstrated utility in orthopaedic applications, such as ankle syndesmosis repair.

Purpose: To assess the cyclic gap formation of a quadriceps tendon repair technique using an adjustable cortical fixation device compared with repair with knotless suture anchors and suture tape, a modification of conventional suture anchor repair.

Study Design: Controlled laboratory study.

Dermal allograft superior capsule reconstruction biomechanics and kinematics.

Purpose: To investigate the effect of a dermal allograft superior capsule reconstruction (SCR) on kinematics and joint pressure biomechanics immediately after simulated superior irreparable rotator cuff tear.

Methods: This controlled laboratory study tested 8 fresh-frozen cadaveric shoulders using a custom test frame. Balanced loading configuration centered the humeral head on the glenoid, and unbalanced load created a force pulling the head toward the acromion.

Minimally Invasive Intramedullary Screw Versus Plate Fixation for Proximal Phalanx Fractures: A Biomechanical Study.

Purpose: To compare the maximum interfragmentary displacement of short oblique proximal phalanx (P1) fractures fixed with an intramedullary headless compression screw (IMHCS) versus a plate-and-screws construct in a cadaveric model that generates finger motion via the flexor and extensor tendons of the fingers.

Methods: We created a 30° oblique cut in 24 P1s of the index, middle, ring, and little fingers for 3 matched pairs of cadaveric hands. Twelve fractures were stabilized with an IMHCS using an antegrade, dorsal articular margin technique at the P1 base.

Altered Glenohumeral Biomechanics in Proximal Humeral Fracture Malunion.

Introduction: There is little biomechanical evidence to support the traditional guideline that 45° represents acceptable proximal humerus deformity. We evaluated glenohumeral contact pressure (GP) and area, subacromial contact pressure, and joint abduction to assess biomechanical changes with different proximal humerus deformities.

Methods: Fifteen fresh-frozen cadaver shoulders were used.

High-Strength Suture Tape Augmentation Improves Cyclic Gap Formation in Transosseous Patellar Tendon Repair: A Biomechanical Study.

Purpose: To compare gap displacement at various intervals of cyclic testing and biomechanical load to failure of a Krackow patellar tendon repair augmented with high-strength suture tape versus the standard Krackow transosseous technique for inferior pole patellar tendon rupture.

Methods: Twelve matched pairs of cadaveric knees were used (8 males and 4 females; mean age 79.6 years, range 57 to 96).

Biomechanical Comparison of Hook Plate vs Headless Compression Screw Fixation of Large Fifth Metatarsal Base Avulsion Fractures.

Background: Debate exists on the optimum fixation construct for large avulsion fractures of the fifth metatarsal base. We compared the biomechanical strength of 2 headless compression screws vs a hook plate for fixation of these fractures.

Methods: Large avulsion fractures were simulated on 10 matched pairs of fresh-frozen cadaveric specimens.

Load to Failure and Stiffness of Interference Screw vs Pulvertaft Weave for Distal Fixation in Peroneal Allograft Reconstruction.

Background: Allograft reconstruction of the peroneal tendons is an option for treatment of major tears of 1 or both peroneal tendons. No consensus on a superior distal fixation method has been reported. The purpose of the study was to compare load to failure and stiffness of a Pulvertaft weave (PTW) through a residual tendon stump to direct-to-bone interference screw (IS) fixation.

Staple-Plate Plus Screw vs Screw Alone in Talonavicular Arthrodesis: A Cadaveric Biomechanical Study.

Background: This study evaluated whether the addition of a nitinol staple-plate to a single cannulated screw increased the mechanical stability for a talonavicular fixation construct.

Methods: Twenty matched pairs of cadaveric feet were randomized to fusion with either a single 5.5-mm cannulated screw or a screw and a plate with 2 screws and a slot with an 18-mm nitinol staple.

Contact Pressure between Digital Flexors and Plates for Distal Radius Approaches.

 Flexor tendon irritation or rupture following open reduction and volar plate fixation of distal radius fractures can cause significant morbidity and necessitate additional surgical intervention.  To compare the impact of the extended flexor carpi radialis (e-FCR) and standard flexor carpi radialis (FCR) approaches on contact pressures between the flexor tendons and volar distal radius plates.  Eight matched pairs of fresh frozen cadavers had each limb randomized to undergo either the e-FCR or standard FCR approach.