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Adult Orthopaedics




Timothy Wright, PhD

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The mission of the Department of Biomechanics is to apply principles of engineering and materials science to solve orthopaedic problems by conducting basic and applied research that translates to the development of orthopaedic devices and instrumentation aimed at improved patient care.

Recent Achievements

3D printing has allowed the introduction of porous cone-shaped complex metallic structures intended to fill bony defects left behind when an existing total knee replacement loosens and must be revised. We demonstrated that cones can help reduce the risk of implant-cement debonding and allow surgeons to use shorter stemmed implants with comparable biomechanical behavior to longer stems.

Both the position in which a sports medicine surgeon places an anterior cruciate ligament (ACL) graft within the anatomic femoral footprint of the native ACL and the flexion angle at which the graft is fixed are important considerations in ACL reconstruction surgery. We showed that grafts placed high within the femoral footprint and fixed at a lower flexion angle carried less force as the knee was flexed compared to grafts placed lower within the femoral footprint and fixed at a higher flexion angle, which could extend the useful life of the reconstruction.

We compared the relative positions and orientations of the wrist bones after two surgical procedures intended to repair a ruptured scapholunate ligament: the dorsal fiber-splitting capsulotomy (FSC) approach intended to preserve the dorsal ligaments of the proximal row of wrist bones and a new dorsal window approach being developed by surgeons at HSS. We found that the FSC can create deleterious changes in wrist posture while the new window approach does not alter the posture and should be considered when performing ligament repair.

In our continuing development of polyvinyl alcohol (PVA) implants to treat cartilage defects in the early stages of osteoarthritis, we measured how PVA implants affect load transfer across the knee joint during gait. Our preclinical testing model provided unique biomechanical evidence for the use of these novel implants by demonstrating that implants with higher PVA content provided improved load transfer.

Notable Publications

Lateral Extra-articular Tenodesis Alters Lateral Compartment Contact Mechanics under Simulated Pivoting Maneuvers: An In Vitro Study. Marom N, Jahandar H, Fraychineaud TJ, Zayyad ZA, Ouanezar H, Hurwit D, Zhu A, Wickiewicz TL, Pearle AD, Imhauser CW, Nawabi DH. Am J Sports Med. 2021 Sep;49(11):2898-2907. doi: 10.1177/03635465211028255. Epub 2021 Jul 27. PMID: 34314283

Do Metaphyseal Cones and Stems Provide Any Biomechanical Advantage for Moderate Contained Tibial Defects in Revision TKA? A Finite-Element Analysis Based on a Cadaver Model. Quevedo González FJ, Meyers KN, Schraut N, Mehrotra KG, Lipman JD, Wright TM, Ast MP. Clin Orthop Relat Res. 2021 Nov 1;479(11):2534-2546. doi:0.1097/CORR.0000000000001912. PMID: 34351312

Synthetic PVA Osteochondral Implants for the Knee Joint: Mechanical Characteristics During Simulated Gait. Chen T, Brial C, McCarthy M, Warren RF, Maher SA. Am J Sports Med. 2021 Sep;49(11):2933-2941. doi: 10.1177/03635465211028566. Epub 2021 Aug 4. PMID: 34347534

Is the Dorsal Fiber-Splitting Approach to the Wrist Safe? A Kinematic Analysis and Introduction of the "Window" Approach. Loisel F, Wessel LE, Morse KW, Victoria C, Meyers KN, Wolfe SW. J Hand Surg Am. 2021 Dec;46(12):1079-1087. doi: 10.1016/j.jhsa.2021.05.029. Epub 2021 Jul 27. PMID: 34325942

Looking Ahead

The disconnect between computational studies of biomechanics of total knee arthroplasty (TKA) at the whole joint level and those focused on the interface level between the implants and the surrounding bone hinders our understanding of TKA function as a whole and prevents identifying tradeoffs between these levels. We have developed a workflow to assess TKA biomechanics holistically by integrating musculoskeletal and finite element models. In a preliminary application of the workflow, we demonstrated that the whole joint kinematics markedly influence the bone-implant interaction at the interface level. We are the first to connect musculoskeletal and finite element modeling techniques to evaluate holistically the tradeoff between joint function and bone-implant interaction.

Patients sometimes express dissatisfaction with the outcomes of their knee replacements because their replaced knees feel either too stiff or too unstable. We continue to work with a multidisciplinary team to investigate the genetic, biological, clinical and biomechanical factors that can lead to a stiff knee, often requiring manipulation or even revision surgery to treat. We are also working with clinical researchers at HSS to develop improved patient-reported outcome measures to capture how patients define their instability and to link these feelings to objective measures of instability made in our newly developed knee dynameter.

As part of our CAMEO (Center for Advanced Materials and Engineering in Orthopaedics) program with Cornell’s College of Engineering, we are engaging teams of Master of Engineering students from Cornell to work with HSS engineers and surgeons on clinically relevant projects, providing them with experiential learning opportunities while also advancing HSS research and development. One of our current projects is to develop a research tool using sensors, a data capture system and telemetry to monitor parents’ usage of a baby carrier designed to prevent the baby from developing hip dysplasia.

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