> Skip repeated content


Minimally Invasive Surgical Approach versus Standard Total Knee Arthroplasty: A Prospective Randomized Double Blinded Study Comparing Postoperative Strength

IRB Number: 26115
(inactive trial)

Institutional Review Board, Hospital for Special Surgery

May 16, 2008

The safety of study participants is our top priority. The trial is approved and periodically reviewed by an Institutional Review Board (IRB), which includes doctors, administrators, ethicists, and members of the general public. The safety of clinical trials is reviewed by the U.S. Food and Drug Administration.

Before enrolling in a clinical trial, the investigator will explain the purpose of the trial, its expected benefits, any possible risks or side effects, and what your role will be. This is the time to ask questions! If you want to join the trial, you must sign the informed consent documents. You can leave a clinical trial at any time without penalty.

For further information, see Understanding Clinical Trials.

Principal Investigator

Bryan J. Nestor, MD


Charles Toulson MD
Howard Hillstrom, PhD
Sherry Backus, PT, DPT, MA
Kristin Foote, MEd
Stephen Lyman, PhD
Russell Windsor, MD


The purpose of this study is to compare two surgical approaches used when performing a total knee replacement by a minimally invasive (MIS) approach.  The goal of this study is to determine what the differences are in post-operative pain, strength and walking following total knee replacement based upon the surgical approach and incision.  The investigators will compare the approach used most often in MIS surgery, a reduced length midline or (“standard approach”) and a minimally invasive approach (“MIS approach”) utilizing a midvastus quadriceps incision. 

Your overall participation will be over a period of 3 months with the first testing visit pre-operatively and the other 3 visits after your surgery.

At the time of your total knee surgery for both knees, the investigators will randomly select one knee for the “standard approach” and one knee for the “MIS approach.”  The skin incision length will be identical in each knee but the approach through the quadriceps tendon will be different.  The randomization means that the selection of which approach is used for which knee is determined by chance. The statistician will set up a list that determines the selection of which approach will be used on each of your knees. Only your doctor and the operating team will know which approach will be used for each knee.  This is termed “blinding.” 

Blinding is important because it allows the investigators to study whether one technique is better that the other without bias being introduced by the patient or the surgeon.  Once your surgery has been performed a physical therapist will “blindly” evaluate your post-operative progress without knowing which knee received which technique.  This way, data can be gathered and unbiased conclusions can be made.
Both standard and MIS techniques have been used safely in performing total knee replacements.  Our goal in this study is to determine whether one particular technique allows for a faster recovery of strength, less pain, and an increased knee range of motion after surgery.

The standard and MIS techniques for performing total knee replacement are different in respect to exposure (opening of the knee joint) during surgery. In the MIS approach utilizing a reduced length, standard knee replacement technique, the tendon that is most responsible for leg extension (making the leg straight) is partially cut to allow the patella (knee cap) to be completely flipped over.  In the MIS technique utilizing the subvastus approach, the tendon that is most responsible for leg extension is preserved.  However, muscle on the medial (inside) side of the knee is split and the kneecap is only partially flipped.  Both techniques are essentially the same after the exposure is performed.  It should be noted, that BOTH these approaches are routinely used by surgeons throughout the world.

In order to make sure that both incisions look similar, the length of both the standard approach and the MIS approach will be the same.  The choice of the total knee replacement used will be determined by your doctor based upon the usual clinical factors and will not be affected by your participation in this study.  The remainder of the surgical procedures and your hospital stay, including anesthesia, medications, physical therapy and nursing care are unchanged by the choice of surgical approach. Only the surgical approach will be randomized (selected by chance).

There are four (4) visits scheduled for this study:
Pre-operative visit (during the month before surgery)
Three (3) weeks after surgery
Six (6) weeks after surgery
Three (3) months after surgery

Inclusion/Exclusion Criteria

Inclusion criteria:  All patients with osteoarthritis and rheumatoid arthritis undergoing primary bilateral total knee replacement.

Exclusion criteria:  Patients with body mass index (BMI) > 35, deformities requiring bone graft / metal augmentation, undergoing treatment for concurrent hip, spine, foot or ankle condition, unable to actively participate in physical therapy/study testing will be excluded.  Previous arthroscopic knee surgery will not preclude patients from being included in the. However, patients with previous open knee surgery (i.e. high tibial osteotomy) will be excluded.

Patients will serve as their own control because each patient will have one TKA performed by the MIS technique and the opposite knee will receive a TKA performed by the standard technique.

Contact Information

Kristin Foote