Comparison of Three Surgical Techniques to Achieve Patella Symmetry During Resection
Condition: Arthroplasty, Replacement, Knee; Injuries, Knee
MeSH terms: Knee Injuries
Study type: Interventional

Summary: 
      This research was performed to determine which of the three techniques used by knee surgeons
      at the Mayo Clinic was the most accurate at the surgical removal (resection) of the knee-cap
      (patella) in a symmetric fashion during total knee replacement (arthroplasty). Although all
      three techniques are known to be effective, the three techniques had never been compared to
      one another to determine if one was more effective than the others at resecting the patella.
    

Detailed description: 
      Resection of the patella to prepare it for placement of a patellar prosthesis is a procedure
      that is performed routinely in the vast majority of total knee arthroplasties (TKA) in the
      United States and at the Mayo Clinic. This procedure is performed by a number of different
      techniques that have been proved to be safe and effective. Despite this, patellar
      instability, tilt, obliquity, and maltracking are all possible complications of improperly
      resected patellae during TKA. The goals of resection are to create a patella that is
      symmetrical, absent of obliquity (slanting), and thick enough to receive a patellar
      prosthesis. Although outcomes are generally good for most described methods, to date, little
      had been published regarding direct comparison of these methods.

      Patients undergoing TKA with planned patellar resection were randomized to have their patella
      resected by one of three methods during primary TKA: 1) use of a cutting guide, 2) haptic
      feedback, or 3) free-hand resection guided by four quadrant measurements. There were three
      experienced fellowship-trained arthroplasty surgeons (hip and knee) performing the procedures
      who were all familiar and experienced with each of the three techniques being investigated.
      Each surgeon, within a group of 30 of their patients, performed a total 10 resections using
      each of the three methods listed above (30 resections per surgeon for a total of 90
      resections).

      Before and after resection measurements of knee-cap thickness were taken and used to
      determine patellar symmetry. The resulting symmetry of each of the three techniques was then
      be compared between and within each of the three techniques and surgeons. Each procedure was
      also be timed from first measurement by the staff surgeon to the final measurement by that
      surgeon.
    

Intervention name(s): Cutting Guide Technique; Haptic Feedback Technique; Four Quadrant Technique
Intervention type(s): Procedure; Procedure; Procedure
Intervention description(s): The guide is clamped onto the patella and tightened so that it remains stable. The guide has a slot that allows insertion of a standard sagittal saw blade, and this slot guides the blade as it is advanced across the patella. The thickness is then measured in the center of the patella to ensure that the resection goal is achieved. Additional resection may be performed as needed.; It consists of a free hand cut (no guide used) with a standard sagittal saw that is oriented based on osteo-cartilaginous landmarks and haptic palpation of the patella by the surgeon. The resection thickness/obliquity can be altered based on haptic feedback (use of the sense of touch) of the patella. The thickness is then measured in the center of the patella to ensure that the resection goal is achieved. Additional resection may be performed as needed.; Resection is performed in a free handed fashion, but after resection, the thickness of the patella is measured separately in all four quadrants (superolateral, superomedial, inferomedial, and inferolateral). Additional resection is performed as needed based on the quadrant measurements and the measurements are repeated after each resection until satisfactory resection thickness and symmetry are obtained.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment