Joint Stiffness: Complications Following Knee Replacement Surgery

In a relatively recent article 1 published in the Musculoskeletal Journal of Hospital for Special Surgery, Dr. Alejandro Gonzalez Della Valle et al reviewed the origins of and treatments for early onset stiffness,  a common complication following knee replacement surgery. We’ll present a brief summary of the article here.

How Prevalent is Stiffness after Knee Replacement?

In a review of the literature, the authors state that stiffness occurs in roughly 6% of cases, making it the most common knee replacement surgery complication.

How is Stiffness Defined?

The researchers reveal that what is perceived as “stiffness” following knee replacement has evolved over time. Several years ago, a knee was considered stiff if the patient could not extend their knee beyond 25 degrees of flexion (that is, a flexion contracture of 25 degrees) or if the full arc of motion was less than 45 degrees. More recently, as surgical technique and implant design have improved and as younger, more active patients receive implants, expectations have changed. Today, stiffness has been defined as a equal to or greater than only 10 degrees or an arc of motion less than 95 degrees. The authors note that this degree of motion is what is required for common activities of daily living (walking, sitting, stair climbing). Practically speaking, a joint can be considered “stiff” when it limits the patient’s ability to perform such activities.

What Causes Stiffness after Knee Replacement?

The authors place the causes of stiffness into three broad categories:

Preoperative – These include things like post-traumatic osteoarthritis, patients with prior high tibial osteotomy and patient whose preoperative range of motion (ROM) is limited.

Intraoperative – Included here are what the authors termed “technical errors” during the procedure. Things like, improperly sized implants and poor “balancing” of the joint through improper bone preparation fall into this category. The researchers explain these as well as other technical errors in detail.

Postoperative - Following surgery, stiffness can be caused by additional factors. Some examples are by patient behavior (“poor patient motivation”) deep infection and inadequate pain management.

How is Stiffness Treated

The authors then outline the various ways in which stiffness can be treated following knee replacement. Manipulation of the knee by the surgeon under anesthesia is generally successful when used within the first three months after surgery. After this period, more aggressive surgical options should be considered since manipulation can result in fracture or soft-tissue damage. Some surgical treatments described are arthroscopy, tibial insert (or spacer) exchange and revision surgery (i.e. exchange of the femoral component typically to correct imbalance in the spacing between the thigh and shin bone created at the time of surgery). The authors also stress the importance of proper rehabilitation following knee replacement.

The original article is available online through PubMed Central.

1. Gonzalez Della Valle A, Leali A, Hass S: Etiology and Surgical Interventions for Stiff Total Knee Replacements. HSSJ 2007, 3: 182-189

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Knee Replacement Allergies – Nothing to Sneeze At?

Knee Replacement Allergies – Nothing to Sneeze At?

Each year, hundreds of thousands of knee replacements are performed. In knee replacement, the worn ends of the bones that make up the knee joint are replaced with metal and plastic implants. In most cases, results are excellent, however in rare cases, an immune response may arise and can become problematic. That is, the patient may suffer from an allergy or hypersensitivity to the metallic components of the implant. Symptoms may include warmth or swelling at the knee, a skin rash and even loosening of the implant.1

This phenomenon is so rare, that its very existence has been debated. But at this year’s annual meeting of the American Academy of Orthopaedic Surgeons, a paper was presented documenting what appear to be allergic reactions to knee replacements.2 Dr. Alvin Ong et. al. recorded 19 cases from 2005-2008 where total knee replacement failures were attributed to metal sensitivity. The authors ruled out all other possible causes of implant failure and then performed a special test, the lymphocyte transformation test (LTT) which looks at a patients sensitivity to certain metals. Seventeen of the nineteen patients with failed knee replacements were tested. Ten patients recorded high sensitivity while the remaining seven indicated mild sensitivity.

Following the sensitivity testing, 16 of the patients had a second procedure where the traditional metal was removed and replaced with a non-metallic implant (the ceramic Oxinium implant from manufacturer Smith and Nephew). Following this knee replacement, the authors reported good results and elimination of the inflammation that was present with the traditional metal implant.

So although an allergic reaction to metal knee replacement implants may be rare, it is not unheard of. Unfortunately, diagnostic tests like LTT are relatively expensive and persons testing positive are not always symptomatic.1 In their article, Dr. Ong et. al. suggest that surgeons be mindful of the possibility of metal hypersensitivity especially when failures of implants are noted and cannot be attributed to other factors.

1 Rabin SI, Graf CN, Hopkinson, WJ, Hallab NJ “Immune Response to Implants.” emedicine.medscape.com. 08 Mar. 2009. <http://emedicine.medscape.com/article/1230696-overview>

2 Jafari SM, Della Valle CJ, Orozco F, Ong AC. “Metal Hypersensitivity Following Total Knee Arthroplasty: A Real Phenomenon?” 2009 AAOS Annual Meeting, Poster No. P134

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