Bone Tunnel Widening Following ACL Reconstruction

This will be a prospective study for patients undergoing ACL reconstruction using
bone-patella tendon-bone graft, hamstring graft or achilles allograft. Each group will have
ACL reconstruction with fixation using bioabsorbable interference screws on the femoral and
tibial side. Patients will be evaluated on the day of surgery, 6, 12, 24, 52 and 104 weeks
post-operatively. Evaluations will include pre-operative regional and standard bone mineral
density measurements, post-operative MRI evaluation of tunnel dimensions and bone-tendon
interface, radiographic evaluation of tunnel dimensions and routine clinical follow-up.

Interventions or Observations - outline specific procedures, treatments and/or
interventions, as well as sources of research material to be utilized, which will involve
human subjects or human materials that will be part of this research project.

This study will require a pre-operative bone mineral density measurement in the Nuclear
Medicine Division of the Department of Radiology at HSS. Standard measurements of the
femoral neck, spine as well as regional studies of the distal femur and proximal tibia of
the injured knee will be performed.

On the day of surgery, the patient will undergo ACL reconstruction using bioabsorbable
interference screw fixation of the hamstring, bone-patella tendon-bone graft, or achilles
allograft. This is a standard procedure. The choice of graft type (hamstring, bone-patella
tendon-bone graft, or achilles allograft) will be discussed with the patients and the
patient will decide graft type pre-operatively. In this study, we will standardize the
fixation method by using bioabsorbable interference screws. Post-operatively, the patient
will undergo a limited MRI scan to evaluate the tunnel dimensions as well as graft placement
prior to discharge from the hospital.

During the patients' 6 weeks, 12 weeks and 24 weeks clinical follow-up, they will be
evaluated by their orthopaedic surgeon for clinical progress. Standard radiographs will be
obtained of the patient's knee at the 6 weeks and 24 weeks follow-up visit. These are
standard radiographic evaluations and are of no additional charge to the patients. We will
utilize these images for radiographic measurements of tunnel expansion. During these visits,
the patients will also undergo limited MRI scan of the femoral tunnel and tibia tunnel. With
the serial MRI images, we will be able to make accurate measurements of the femoral and
tibial tunnels. In addition, we will be able to evaluate the bone-tendon interface as well
as the maturation of the intra-articular portion of the ACL graft. At 24, 52 and 104 weeks
the patients will also be given standard IKDC and Lysholm clinical knee outcome
questionnaires and will have objective stability measurements of both the operative and
non-operative knees using a KT-1000 instrument.

Overall Study Protocol:

Pre-operative work-up

1. Bone mineral density measurement by D.E.X.A.

Day of Surgery:

1. ACL reconstruction using bioabsorbable interference screws

2. Limited CT scans to quantitate tunnel dimensions

6 weeks post-operatively

1. Regular clinical follow-up

2. Regular plain radiographs to quantitate tunnel dimensions

3. Limited MRI scans to quantitate tunnel dimensions

12 weeks post-operatively

1. Regular clinical follow-up

2. Limited MRI scans to quantitate tunnel dimensions

24 weeks post-operatively

1. Regular clinical follow-up and KT-1000 measurements

2. Regular plain radiographs to quantitate tunnel dimensions

3. MRI study to evaluate tendon-bone interface, graft maturation, tunnel dimensions and
trabecular remodeling

4. Patients will answer IKDC and Lysholm knee questionnaires

52 weeks post-operatively

1. Regular clinical follow-up and KT-1000 measurements

2. Patients will answer IKDC and Lysholm knee questionnaires

3. Limited MRI

104 weeks post-operatively

1. Regular clinical follow-up and KT-1000 measurements

2. Patients will answer IKDC and Lysholm knee questionnaires

3. Limited MRI

Number of Subjects (power justification for numbers)

A power analysis was performed to determine the number of subjects needed to determine
significance between the hamstring and bone-patella tendon-bone group. Data from previous
studies demonstrate tunnel widening up to 77 ± 28% following ACL reconstruction using
hamstring tendons. We estimate that a 30% decrease in this amount of tunnel widening would
be clinically significant. This extrapolates to a 54% increase in tunnel dimensions. Using
these estimations, a power of 0.80 with α = 0.5 is achieved using 20 subjects per group
(BPTB versus hamstring).

Inclusion Criteria:

- Individuals within the age range of 18 to 55 years who are diagnosed with anterior
cruciate insufficiency and have decided to undergo ACL reconstruction using
autogenous graft will be included in the study.

Exclusion Criteria:

- Individuals that have previous knee surgeries, multi-ligament injuries, systemic
ligament disorders such as Ehlers Danlos syndrome or connective tissue disorders will
be excluded from the study.

- Individuals who are pregnant or expect to be pregnant during the course of the study
or who are especially concerned with X-ray exposure should also be excluded.