Bone Tunnel Widening Following ACL Reconstruction
Condition: Anterior Cruciate Ligament Injury; Knee Injuries
MeSH terms: Wounds and Injuries; Knee Injuries; Anterior Cruciate Ligament Injuries
Study type: Interventional

Summary: 
      Hypothesis 1: There is less tunnel-widening with bone-patella tendon-bone graft compared with
      the hamstring graft when the same fixation method is used. Tunnel widening is greater with
      achilles tendon allografts versus autograft bone-patella tendon-bone and hamstring
      autografts.

      Hypothesis 2: Tunnel widening occurs in the early post-operative period (< 8 weeks) when the
      tendon remodels within the bone tunnels.

      Hypothesis 3: Low pre-operative bone mineral density is associated with tunnel widening.
    

Detailed description: 
      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).
    

Intervention name(s): Surgical reconstruction of the ACL
Intervention type(s): Procedure
Intervention description(s): Surgical reconstruction of the ACL
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: ACL; Tunnel; Widening