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040 a| EREb| enge| rdac| ERE;

035 a| (OCoLC)1547764708;

049 a| EREE;

100 1 a| Klemm, Elizabeth Me| author?| UNAUTHORIZED;

245 10 a| Hamstrings and Quadriceps Muscle Recruitment Following ACL Reconstruction with an Autograft;

264 1 a| [Greenville, N.C.] :b| [East Carolina University],c| 2025.;

300 a| 142 pages;

336 a| textb| txt2| rdacontent;

337 a| computerb| c2| rdamedia;

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502 c| East Carolina Universityd| 2025.;

504 a| Includes bibliographical references.;

520 3 a| Anterior Cruciate Ligament reconstructions (ACLr) are one of the most common kneesurgeries. The torn ligament is most often reconstructed with an ipsilateral autograft from thesemitendinosus (ST), patella (PT), or quadriceps (QT) tendon. Surgical outcomes are generallypositive, but around 50% of individuals develop osteoarthritis in the 15 years after their ACLr.The reasons for this are not completely understood, but reduced and altered knee joint loadinghave been suggested as the probable causes. It has also been shown that the ST tendon does notrestore its pre-surgical properties with reduced tendon stiffness, reduced fibril organization, andincreased length common. This study hypothesized that donor site tendon stiffness would also bereduced following ACLr with a BPTB or QT graft. Additionally, it hypothesized that thesealtered donor site tendon properties would cause altered muscle group force sharing in thehamstrings (ST graft) or quadriceps (BPTB and QT grafts). These deficits would be mostpronounced at shorter muscle lengths and lower isometric torque levels and cause a shift of thetorque-length curve towards longer muscle lengths.Data were collected on 15 participants who had an ACLr (5 ACLr - ST; 6 ACLr - PT; 4ACLr - QT) and 11 healthy matched controls. Participants completed isometric contractions(knee flexion for ACLr - ST and Healthy - ST; knee extension for ACLr - PT, ACLr - QT, andHealthy - PT) in four different positions that altered muscle length and two different torquelevels while active shear wave elastography images were taken of the muscles in the hamstringor quadriceps groups. Active shear modulus was multiplied by muscle PCSA to estimate muscleforces. EMG data were also collected. Donor site tendon shear modulus was also measured. Bothlimbs were tested, with the unaffected limb serving as an estimate of pre-ACLr behavior.Dependent samples t-tests, repeated measures ANOVAs, and effect sizes were calculated withinthe ACLr and healthy groups to test for between limb and within limb differences.The ACLr - ST group had consistently lower ST tendon stiffness on the injured side andproduced less force out of the affected ST. Deficits in force production were not affected bycontraction level, but they were smaller at longer muscle lengths. The degree of ST tendonstiffness recovery did not impact the size of ST force deficits and there were no consistent shiftsin the torque-length curve. Donor site tendon stiffness was not consistently lower in the PT orQT following ACLr with these grafts. As such, there were no large effects on quadriceps muscleforce production or load sharing. This improved healing of the PT and QT compared to the ST islikely due to the surgical technique. While the entire ST tendon is used for ACLr, only a portionof the PT and QT are sourced which leaves a scaffold for the tendon to regenerate on.This study was limited by small sample sizes per each graft type; however, it suggestedthat donor site tendon recovery is more complete following ACLr with a PT or QT autograft thanwith a ST graft and that deficits in the ST tendon lead to reduced force production. Futureresearch should examine the timeline of PT and QT recovery, as well as explore rehabilitationtechniques that can preferentially activate the ST to improve tendon healing and consequentlynormalized knee joint loading due to more normal knee flexor force sharing.;

653 a| ACL reconstruction;

653 a| anterior cruciate ligament;

653 a| shear wave elastography;

653 a| tendon properties;

653 a| muscle force;

653 a| autograft;

700 1 a| Domire, Zachary J.e| degree supervisor.?| UNAUTHORIZED;

710 2 a| East Carolina University=| ^A637090;

856 40 z| Access via ScholarShipu| http://hdl.handle.net/10342/14331;

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Hamstrings and Quadriceps Muscle Recruitment Following ACL Reconstruction with an Autograft

Author/creator	Klemm, Elizabeth M author
Other author	Domire, Zachary J. degree supervisor.
Other author	East Carolina University
Format	Theses and dissertations
Publication	[Greenville, N.C.] : [East Carolina University], 2025.
Description	142 pages
Supplemental Content	Access via ScholarShip

Summary	Anterior Cruciate Ligament reconstructions (ACLr) are one of the most common kneesurgeries. The torn ligament is most often reconstructed with an ipsilateral autograft from thesemitendinosus (ST), patella (PT), or quadriceps (QT) tendon. Surgical outcomes are generallypositive, but around 50% of individuals develop osteoarthritis in the 15 years after their ACLr.The reasons for this are not completely understood, but reduced and altered knee joint loadinghave been suggested as the probable causes. It has also been shown that the ST tendon does notrestore its pre-surgical properties with reduced tendon stiffness, reduced fibril organization, andincreased length common. This study hypothesized that donor site tendon stiffness would also bereduced following ACLr with a BPTB or QT graft. Additionally, it hypothesized that thesealtered donor site tendon properties would cause altered muscle group force sharing in thehamstrings (ST graft) or quadriceps (BPTB and QT grafts). These deficits would be mostpronounced at shorter muscle lengths and lower isometric torque levels and cause a shift of thetorque-length curve towards longer muscle lengths.Data were collected on 15 participants who had an ACLr (5 ACLr - ST; 6 ACLr - PT; 4ACLr - QT) and 11 healthy matched controls. Participants completed isometric contractions(knee flexion for ACLr - ST and Healthy - ST; knee extension for ACLr - PT, ACLr - QT, andHealthy - PT) in four different positions that altered muscle length and two different torquelevels while active shear wave elastography images were taken of the muscles in the hamstringor quadriceps groups. Active shear modulus was multiplied by muscle PCSA to estimate muscleforces. EMG data were also collected. Donor site tendon shear modulus was also measured. Bothlimbs were tested, with the unaffected limb serving as an estimate of pre-ACLr behavior.Dependent samples t-tests, repeated measures ANOVAs, and effect sizes were calculated withinthe ACLr and healthy groups to test for between limb and within limb differences.The ACLr - ST group had consistently lower ST tendon stiffness on the injured side andproduced less force out of the affected ST. Deficits in force production were not affected bycontraction level, but they were smaller at longer muscle lengths. The degree of ST tendonstiffness recovery did not impact the size of ST force deficits and there were no consistent shiftsin the torque-length curve. Donor site tendon stiffness was not consistently lower in the PT orQT following ACLr with these grafts. As such, there were no large effects on quadriceps muscleforce production or load sharing. This improved healing of the PT and QT compared to the ST islikely due to the surgical technique. While the entire ST tendon is used for ACLr, only a portionof the PT and QT are sourced which leaves a scaffold for the tendon to regenerate on.This study was limited by small sample sizes per each graft type; however, it suggestedthat donor site tendon recovery is more complete following ACLr with a PT or QT autograft thanwith a ST graft and that deficits in the ST tendon lead to reduced force production. Futureresearch should examine the timeline of PT and QT recovery, as well as explore rehabilitationtechniques that can preferentially activate the ST to improve tendon healing and consequentlynormalized knee joint loading due to more normal knee flexor force sharing.
Dissertation note	East Carolina University 2025.
Bibliography note	Includes bibliographical references.
Technical details	System requirements: Adobe Reader.
Technical details	Mode of access: World Wide Web.

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Hamstrings and Quadriceps Muscle Recruitment Following ACL Reconstruction with an Autograft

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