Symmetric balance of flexion-extension gaps crucial for TKR

Chief Medical Editor Douglas W. Jackson, MD, interviews Douglas E. Padgett, MD, about his strategies for avoiding a stiff total knee replacement.

Issue: January 2004

Douglas W. Jackson, MD: What are some tips and clues to identify the at-risk group with regard to the stiff total knee replacement (TKR)?

Douglas E. Padgett, MD

Douglas E. Padgett, MD,
Associate Professor of Orthopaedics,
The Hospital For Special Surgery,
New York

Douglas E. Padgett, MD: While the historical teaching has always been that the best predictor of postoperative motion following total knee arthroplasty is preoperative motion, improvements in total knee design and postoperative management bring this dictum into question. There are, however, groups that seem to predictably challenge our ability to obtain motion following total knee replacement.

Patients in whom there has been a long-standing loss of motion resulting in flexion of less than 90º as well as large fixed varus or valgus deformity present some of the greatest challenges. The functional loss of stairclimbing ability, ability to negotiate a cycle as well as arise from a low chair are tremendous disabilities and correction of these deficits remain top priorities.

[photo]
For the sixth varus deformity, extensive medial relief as shown is required.

COURTESY OF DOUGLAS E. PADGETT

The role of soft tissue compliance, I believe, is under-appreciated in understanding the risk of poor motion following surgery. The loss of the normal elasticity of the soft tissue envelope about the knee is especially apparent in the multiply operated limb, the post-traumatic knee and the knee with evidence of preoperative heterotopic bone. I attempt to get a general sense of soft tissue status by simply palpating the extensor mass, assessing patellar mobility, and feeling for general laxity of the overlying skin. While difficult to quantify, I often get a general sense of how contracted the soft tissues about the knee are.

The final at-risk group for stiffness following total knee is the patient with poor pain tolerance. This is where inquiring about history of pain medication usage is invaluable. The vast majority of patients have managed their arthritis with traditional NSAIDs as well as with acetaminophen. Some patients have been administered narcotic pain medication for management, and it is in this group that particular caution is warranted.

The development of tolerance to many of the narcotic medications makes perioperative management of pain exceedingly difficult. Poor pain control often results in an inability to effectively participate in postoperative protocols and can lead to a loss of motion. A frank discussion regarding expectations after surgery, the amount and duration of narcotic pain medication postoperatively as well as consultation with appropriate pain management is necessary to avoid problems with pain control.

Jackson: Please address intraoperative and postoperative strategies to avoid the stiff knee.

Padgett: The most crucial element for successful total knee arthroplasty is symmetric balance of the flexion-extension gaps. This is achieved through either adequate tissue releases and or ligament advances. I like to think of TKR as a soft tissue operation done in conjunction with bone resurfacing. The most common error encountered during TKR is inadequate ligamentous release: residual tightness medially for the varus knee and lateral tightness for the valgus knee. Failure to adequately release predictably results in a tight knee that does not bend and may not straighten out. The use of spacer block techniques to assess the extent and adequacy of release is crucial. Additionally, surgeons should be familiar with the components of the flexion and extension spaces and how to algorithmically approach looseness or tightness of any scenario.

[x-ray]
Significant preop varus and limited ROM place this patient at risk for postop stiffness.

Intraoperative assessment of femoral sizing, patellar composite thickness, as well as tensioning of the posterior cruciate ligament in cruciate retaining (CR) knees are all fundamental in ensuring that the knee is not tight and will move effortlessly. I make it a point to ensure that all osteophytes are removed, especially off the posterior condyles as well as checking for any masses of acrylic cement following implant insertion. These simple steps can be significant in allowing improved knee flexion.

Of all the strategies to ensure adequate motion postoperatively, I believe adequate pain control is the most important. While personally a big proponent of the use of continuous passive motion, allowing patients to dangle from a chair and early use of the stationary bike, pain management is a necessary adjunct for the well executed knee arthroplasty. Using continuous epidural, supplemental femoral nerve blocks and patient controlled analgesia have improved the recovery from TKR.

Jackson: What are the roles of arthroscopy and manipulation?

Padgett: The main indication for manipulation after TKR is poor motion in an otherwise well performed knee. This requires a degree of surgical introspection: Were ligament releases adequate, are the gaps balanced, is femoral sizing appropriate, is the patellofemoral joint overstuffed, and are there retained osteophytes or cement? These implant intrinsic variables are not amenable to manipulation. A critical assessment of radiographic alignment, soft tissue balance and recollection of motion at the time of arthroplasty is required. Assuming that the arthroplasty was otherwise well performed, if the loss of motion after surgery is due to hemarthrosis, arthrofibrosis or problems with pain control, then manipulation is an option.

The technique of manipulation requires adequate anesthesia and anticipated postoperative pain control. Avoidance of long lever arms by using a two-person technique in order to break any adhesions is the safest and most reliable method.

Arthroscopy can be a useful adjunct to manipulation. I find it most useful in the patient who may have had a moderate hemarthrosis postoperatively that is persistent and starting to scar down the suprapatella pouch. Arthroscopic synovectomy using thermal wands to minimize bleeding have provided much success when performed in conjunction with manipulation. This decompression of peripatellar space appears to be of value in returning the patient to more expected motion.