Farid Amirouche

University of Illinois Chicago | UIC · Department of Orthopaedics (Chicago)

Background: In total hip replacement (THR), the femoral offset (FO) is assessed preoperatively, and the surgeon must determine whether to restore, increase, or decrease the FO based on experience and the patient's clinical history. The FO is known to influence the abductor muscle strength, range of motion (ROM), gait, and hip pain after THR; howev...

Pedicle screws are typically used for fusion, percutaneous fixation, and means of gripping a spinal segment. The screws act as a rigid and stable anchor points to bridge and connect with a rod as part of a construct. The foundation of the fusion is directly related to the placement of these screws. Malposition of pedicle screws causes intraoperativ...

Study Design Narrative review. Objective Despite the numerous treatment options for vertebral compression fractures, a consensus opinion for the management of patients with these factures has not been established. This review is meant to provide an up-to-date overview of the most common treatment strategies for compression fractures and to suggest...

Background An animal nerve scar model that can be used to identify potential therapies in the treatment of nerve scarring in patients has yet to be defined. The purpose of this study was to create an inexpensive, reproducible, and reliable nerve scar model in the rat. Methods Thirty rats underwent left tibial nerve transection and repair and were...

Study Design Analysis of insertion angle and bone density on the pedicle screw fixation strength with a novel testing protocol that accounts for the articular processes. Objective To analyze the relationship between pedicle screw fixation strength and bone mineral density for different transverse screw insertion angles. Summary of Background Data...

Introduction Treatment strategies for irreparable Massive Rotator Cuff Tears (MRCTs) are debatable, especially for younger, active patients. Superior Capsular Reconstruction (SCR) acts as a static stabilizer, while Lower Trapezius Transfer (LTT) serves as a dynamic stabilizer. This study compares the biomechanical effectiveness of SCR and LTT, hypo...

Introduction Supraspinatus and infraspinatus tears (Massive Rotator Cuff Tear- MRCT) cause compensatory activation of the teres minor (TM) and subscapularis (SubS) to maintain humeral head alignment. This study measures force changes in TM and SubS using a dynamic shoulder testing setup. We hypothesize that combining superior capsule reconstruction...

Introduction The human wrist is a highly complex joint, offering extensive motion across various planes. This study investigates scapholunate ligament (SLL) injuries’ impact on wrist stability and arthritis risks using cadaveric experiments and the finite element (FE) method. It aims to validate experimental findings with FE analysis results. Meth...

Introduction Understanding knee joint biomechanics is crucial, but studying Anterior cruciate ligament (ACL) biomechanics in human adolescents is challenging due to limited availability cadaveric specimens. This study aims to validate the adolescent porcine stifle joint as a model for ACL studies by examining the ACL's behavior under axial and tors...

Beyond the surgeon's feedback on bone behavior in the operating room, there is a paucity of data present in the literature on the mechanical properties of pediatric calvarial bone. The present study tested the calvarial bone of four species (Adult Humans, Dog, Pig, and Monkey) to find the mechanical properties. Three types of tests were performed;...

Background Osteochondral defects (OCDs) in the knee joint have significant clinical implications, particularly regarding contact pressures and pressure distribution. Understanding how these factors are influenced by defect size and location is crucial for developing effective therapeutic strategies. Purpose/Hypothesis The purpose of this study was...

In this paper we develop bond-graph representations for ideal mechanical constraints, both embedded and adjoined, by stating and applying the principle of virtual power, at the particle level, to both types of constraints. The resulting system-level bond graph provides a bond-graphic derivation of Kane’s equations for a general nonlinear nonholonom...

Introduction Utilizing large animal model like male pig for biomechanical studies offers a cost-effective approach to understanding human joint and tissue mechanics. Our study explores the osteology and meniscus anatomy of the male porcine stifle joint and compares it to human knee joint parameters, aiming to provide a valuable reference for orthop...

Computer-assisted robots aid orthopaedic surgeons in implant positioning and bony resection. Surgeons selecting a robot for their practice are faced with numerous options. This study aims to make the choice less daunting by reviewing the most commonly used Food and Drug Administration-approved robotic total knee arthroplasty platforms in the Americ...

Purpose This paper investigates the biomechanical benefits of using hybrid constructs that combine cannulated screws with tension band wiring (TBW) cerclage compared to cannulated screws with anterior Variable Angle locking neutralisation plates (VA LNP). These enhancements can bear heavier loads and maintain the repaired patella's integrity, in co...

• We provide a novel bond-graphic derivation of Kane's equations for a general particle system with embedded scleronomic configuration and velocity constraints. • We then reduce Kane's equations to a set of differential equations for the independent generalized velocities, and provide a multibond-graph representation of the reduced equations. • Sim...

Introduction The escalating incidence of anterior cruciate ligament (ACL) injuries, particularly among adolescents, is a pressing concern. The study of ACL biomechanics in this demographic presents challenges due to the scarcity of cadaveric specimens. This research endeavors to validate the adolescent porcine stifle joint as a fitting model for AC...

Introduction The varus and valgus knee deformities result from imbalance in tension between medial and lateral soft tissue compartments. These conditions need to be addressed during total knee arthroplasty (TKA). However, there is no consensus on optimal soft-tissue release techniques for correcting varus and valgus deformities during TKA. We asses...

Transverse patella fractures, accounting for approximately 1% of Orthopedic injuries, pose intricate challenges due to their vital role in knee mechanics. This study aimed to compare the biomechanical performance of a construct, integrating cannulated screws and an anterior locking neutralization plate, with the conventional tension band wiring tec...

Vertebral compression fractures (VCFs) occur in 1 to 1.5 million patients in the US each year and are associated with pain, disability, altered pulmonary function, secondary vertebral fracture, and increased mortality risk. A better understanding of VCFs and their management requires preclinical models that are both biomechanically analogous and ac...

In this paper we develop bond-graph representations for ideal mechanical constraints, both embedded andadjoined, by stating and applying the principle of virtual power, at the particle level, to both types of constraints.The resulting system-level bond graph provides a bond-graphic derivation of Kane's equations for a general nonlinearnonholonomic...

Introduction Current clinical practice suggests using patellar and quadriceps tendon autografts with a 10 mm diameter for ACL reconstruction. This can be problematic for patients with smaller body frames. Our study objective was to determine the minimum diameter required for these grafts. We hypothesize that given the strength and stiffness of thes...

Purpose The purpose of this study is to generate validated prediction rules for metacarpal lengths that can be applied without the need for computation tools to assist with restoration of anatomic length after fracture and utilizes only ipsilateral metacarpals. Methods The anatomic lengths of all hand bones in 50 hands (25 men, 25 women) were used...

» After transplantation revascularization does occur although data are only available for animal models. » The time zero biomechanics, that is, the biomechanical properties at the time of transplant, of a meniscus allograft transplantation appear to appropriately mimic the original so long as the graft is sized correctly within 10% of the original...

The authors’ previously published results on a bond-graph-compatible and nonholonomic momentum form of Kane’s equations are extended, from scleronomic to rheonomic systems. The momentum form is found to be partially Hamiltonian, and bond-graph-compatible velocity forms are also found, of which one is partially Lagrangian. The results are derived fo...

Objective: Lumbar lateral interbody fusion (LLIF) allows placement of large interbody cages while preserving ligamentous structures important for stability. Multiple clinical and biomechanical studies have demonstrated the feasibility of stand-alone LLIF in single-level fusion. We sought to compare the stability of 4-level stand-alone LLIF utilizi...

In this paper we develop bond-graph descriptions for ideal mechanical constraints,both embedded and adjoined, by stating and applying the principle of virtual power,at the particle level, to both types of constraints. The resulting system-level bondgraph provides a bond-graphic derivation of Kane’s equations for a general nonlinear nonholonomic sys...

Background: Biomechanical testing of abduction moment arms presents a useful method to assess the contribution of individual rotator cuff muscles to glenohumeral function. This study aimed to investigate the changes in abduction moment arms after a supraspinatus tear treated with Superior Capsule Reconstruction (SCR), Bursal Acromial Reconstructio...

In this paper we develop bond-graph descriptions for ideal mechanical constraints, both embedded and adjoined, by stating and applying the principle of virtual power, at the particle level, to both types of constraints. The resulting system-level bond graph provides a bond-graphic derivation of Kane's equations for a general nonlinear nonholonomic...

The submitted document is the extended abstract of a paper which will be presented in July if the extended abstract is accepted by the conference reviewers. A shorter abstract (of the paper to be written) is as follows: In this paper we develop bond graph descriptions for ideal mechanical constraints, both embedded and adjoined, by stating and ap...

Study design: Human Cadaveric Biomechanical Study. Objectives: Lumbar Lateral Interbody Fusion (LLIF) utilizing a wide cage has been reported as having favorable biomechanical characteristics. We examine the biomechanical stability of unilateral pedicle screw and rod fixation after multilevel LLIF utilizing 26 mm wide cages compared to bilateral...

Total shoulder arthroplasty is an increasingly popular option for the treatment of glenohumeral arthritis. Historically, the effectiveness of the procedure has largely been determined by the long-term stability of the glenoid component. Glenoid component loosening can lead to clinically concerning complications including pain with movement, loss of...

Background Chondral defects in the knee have biomechanical differences because of defect size and location. Prior literature only compares the maximum stress experienced with large defects. Hypothesis It was hypothesized that pressure surrounding the chondral defect would increase with size and vary in location, such that a size cutoff exists that...

Purpose To provide a biomechanical comparison between human dermal (HD) allograft and long head of biceps tendon (LHBT) autograft with and without posterior side-to-side suturing for superior capsule reconstruction (SCR) Methods 8 fresh-frozen cadaveric shoulder specimens were tested in 5 conditions: (1) intact, (2) complete supraspinatus tear, (3...

Background: The pelvic girdle and spine vertebral column work as a long chain influenced by pelvic tilt. This study aims to assess the effect of open and closed chain anterior pelvic tilt (APT) or posterior pelvic tilt (PPT) on cervical and lumbar spine kinematics using an in vitro cadaveric spine model. Methods: Three human cadaveric spines wit...

The rotator cuff (RC) is a group of four muscles that helps maintain dynamic stability of the glenohumeral joint and provides force rotation of the shoulder [1]. Rotator cuff tears are a common injury that may result in pain and limited joint stability [1]. Superior capsular reconstruction (SCR) and reverse total shoulder arthroplasty (rTSA) are tw...

Introduction: Current understanding of the biomechanical effects of treatment options for irreparable rotator cuff (RC) tears is lacking. This study examines how shoulder muscle lengths and excursions are affected by superior capsular reconstruction (SCR), bursal acromial reconstruction (BAR), and SCR with BAR, following a complete supraspinatus t...

Study Design Pedicle screw study. Objective The selection of pedicle screw parameters usually involves the surgeon’s analysis of preoperative CT imaging along with anatomical landmarks and tactile examination. However, there is minimal consensus on a standardized guideline for selection methods on pedicle screws. We aimed to determine the effects...

Background Lines of action of the superior, middle, and inferior infraspinatus muscle fibers work together to produce moment arms that change throughout abduction in an intact shoulder, after a supraspinatus tear, and after superior capsular reconstruction (SCR) and reverse total shoulder arthroplasty (rTSA). Purpose To use moment arm values to in...

The patellofemoral joint is a complex joint with multiple articulating surfaces and stabilizing forces. Pain and dysfunction of the patellofemoral joint are extremely common orthopedic complaints. The patella articulates with the trochlea of the distal femur, and is stabilized primarily by the medial patellofemoral ligament during early flexion, an...

The authors' previously published results on a nonholonomic momentum form of Kane's equations are extended from scleronomic to rheonomic systems. The momentum form is found to be partially Hamiltonian, and a new velocity form is found that is partially Lagrangian. The results are derived for general particle systems, and then specialized to rigid-b...

Prediction of vertebral properties and associated fracture risk is a serious challenge for patients who have osteoporosis. This study aimed to enhance the prediction capability of the computed tomography-based finite element model (CT/FEM) for the strength, stiffness, and failure pattern of the vertebrae under compression. Twelve thoracic and eight...

A tendon is a closely compact band of connective tissue-fibers well organized in length and strength which connects to muscle and transmits the required force developed by the muscle. The musculoskeletal is such that bones are driven by tendons and produce joint motion in coordination with muscles activities. Each muscle connects to tendon which in...

The knee is a complex 3D joint whose normal function depends on the coordination of a supporting structure made of ligaments, muscles tendons, cartilage, menisci working together to preserve stability and gait. Any disruptions of these soft tissues lead to a mechanical disadvantage, pain, and knee pathologies such as cartilage defect that might req...

Biomechanics principles when applied to orthopedics have shown to lead better approach treatment modalities leading to better quality of life for patients. Biomechanics is now an integral part of orthopedic implant designs, and continues to evolve in the clinical diagnosis and evaluation of complex joint pathologies. Orthopedic biomechanics researc...

The objective of this chapter is to define further the clinical value of moment arms and provide a descriptive approach based on experimental investigation into the calculation of moment arm for the rotator cuff muscles spanning the glenohumeral joint during abduction. With the advent of imaging techniques quantifying the muscle torque capacity can...

The biomechanics of human joints is complex and play a fundamental role in human locomotion, joint stability, and support. The human joint inherent structure and articulating cartilages surface are driven by muscles forces that react to the kinematics preserving stability by optimizing the power capacity needed to achieve a given task. For example,...

Objectives With an increasing incidence over time, anterior cruciate ligament (ACL) rupture can produce functionally limiting knee instability that requires operative treatment to address the instability as well as prevent the development of osteoarthritis. Anteroposterior instability forms the basis of the most sensitive physical exam maneuver to...

Objectives The Rotator Cuff (RC) is formed from the subscapularis, supraspinatus, infraspinatus, and teres minor muscles and their tendinous extensions. The 4 RC tendons insert on the humeral head such that they contribute to the dynamic stability of the glenohumeral joint along with their rotational actions on the shoulder. The moment arm can be u...

Background Diabetes mellitus (DM) increases the risk for carpal tunnel syndrome (CTS) and is associated with its own neuropathic complications. Diabetic peripheral neuropathy (DPN) is a common complication seen in diabetic patients. In this study, we examine the relationship between the severity of DPN and CTS. Methods Type 2 diabetic and control...

PurposeThe rotator cuff (RC) muscles contribute to dynamic stability and rotational actions of the glenohumeral joint. Moment arm can be used to demonstrate the potential work a muscle contributes to a musculoskeletal joint rotation. This study aimed to understand the moment arm contributions of the RC muscles and explore changes following a comple...

Purpose To compare the mechanical characteristics of A2 and combined A2–A4 pulley repair in the intact and damaged flexor pulley system. Methods After control testing, we recorded tendon excursion and flexion of 11 cadaveric fingers after several interventions: (1) complete excision of A2 and A4, (2) repair of the A2 with one ring of tendon graft,...

Background Autologous chondrocyte implantation (ACI) is an increasingly popular technique for the treatment of articular cartilage defects. Because several companies have financial interests in ACI, it is important to consider possible conflicts of interest when evaluating studies reporting outcomes of ACI. Purpose To determine whether there is an...

Purpose The purpose of our pilot study was to assess the effect of augmenting anterior cruciate ligament (ACL) repair with suture tape on biomechanical parameters including anterior tibial translation, gap formation, and load to failure. Methods Ten fresh-frozen nonpaired cadaveric knees were dissected, and baseline anterior-posterior stability of...

This book presents a fundamental basic overview of orthopedic biomechanics in sports medicine, with a special focus on the current methodologies used in modeling human joints, ligaments, and muscle forces. The first part discusses the principles and materials, including the use of finite element analysis (FEA) to analyze the stress-strain response...

Biomechanical evaluation of vertebral strength and failure patterns is essential to the clinical assessment of spinal injuries and in the prediction of osteoporotic fracture. Finite element (FE) models based on CT scans could be an alternative to BMD based measures since these models incorporate material heterogeneity and bone geometry and describe...

Background Degenerative and traumatic changes to the rotator cuff can result in massive and irreparable rotator cuff tears (RCTs). Purpose/Hypothesis The study objective was to conduct a biomechanical comparison between a small, incomplete RCT and a large, complete RCT. We hypothesized that the incomplete supraspinatus (SS) tear would lead to an i...

Background: This investigation compares the bio-mechanical properties of one-third tubular and newer anatomically contoured locking plate-and-screw implants for fixation of Danis-Weber Type B (OTA 44B) distal fibula lateral malleolar fractures in Saw-Bones models. Methods: This study utilized fibula Saw-Bones that were osteotomized to simulate a d...

Purpose To investigate the potential for a suture tape–reinforcement technique to prevent elongation with repetitive use of a human dermal (HD) allograft traditionally used for superior capsule reconstruction in a biomechanical model. Methods Using 8 scapulae and humeri Sawbones models, the standard superior capsule reconstruction was performed us...

Aim of the studyOur objective was to compare biomechanical effects of superior capsular reconstruction (SCR) and reverse total shoulder arthroplasty (rTSA) on shoulder motion, in the setting of an irreparable supraspinatus (SS) tear. We hypothesized that rTSA would produce greater improvement in abduction force and shift the humerus inferiorly, whi...

Background Superior capsule reconstruction (SCR) has been gaining popularity as a treatment for irreparable rotator cuff (RC) tears, especially for younger patients. The present biomechanical study aimed to investigate how SCR affects functional abduction force, humeral head migration, and passive range of motion following an irreparable RC tear. W...

Purpose: To investigate the biomechanical effects of superior capsule reconstruction with subacromial allograft spacer on superior humeral head translation and subacromial contact pressure. Methods: Eight cadaveric shoulder specimens were tested in 4 conditions: (1) intact rotator cuff, (2) supraspinatus tear and superior capsule excision, (3) s...

Despite the extensive literature regarding peripheral nerve stretch injuries, there are few studies that compare the nerve histology with the mechanical properties in humans. There is clinical evidence suggesting that the peroneal nerve is at greater risk for injury compared to the tibial nerve following total hip arthroplasty and hip trauma. We ex...

Background: It has been shown in previous studies that the spine, especially the thoracolumbar region, is vulnerable to high energy impact and trauma.[Waterloo et al.] A high frequency of abnormalities affecting the thoracolumbar spine has been found among athletes in sports with high back impact, lifting and any sport that demands great exertion f...

Preoperative planning is an integral part of total joint arthroplasty, aiming to restore the joint mimicking the native functionality (Choplin 2008).Dimensions of bone and prosthetic implants are usually evaluated by preoperative radiographs to restore leg length discrepancy and femoral offset (Amirouche et al 2015).Nevertheless, even when using de...

Background: Previous studies have aimed to biomechanically improve the transosseous tunnel technique of rotator cuff repair. However, no previous work has addressed tunnel inclination at the time of surgery as an influence on the strength of the repair construct. Hypothesis: We hypothesized that the tunnel angle and entry point would influence t...

Although it is unknown when sports were first played indoors, we know that sports have been around for over 15,000 years, with the first documented event as a footrace between two cavemen. Progress in architecture and technology have allowed for outdoors competition to transition into indoor sporting events. In modern day, indoor sports continue to...