Diagnosis of Patellar Malalignment: A Work in Progress...

If you've been reading my previous blogs, you'll see that I often need to be dragged kicking and screaming into a adopting traditionally held beliefs of the physical therapy profession. As much as some of my colleagues would like otherwise, I will likely hold on to this stubborn characteristic until the day I croak. The upside to my eternal skepticism is the drive to finding evidence supporting or refuting specific approaches to a clinical problem.

I have previously admitted having guerrilla hands with respect to palpation and assessment of the SI joint. I have another confession: I have the eyes of a fruit bat when it comes to visually assessing patellar alignment in patients with anterior knee pain. I assure you I will try to cease comparing various parts of my anatomy to jungle beasts. It's probably just a phase.

Today's research comes to us from the JOSPT on diagnosing patellar malalignment. Patellar malalignment is thought to be at least one of the mechanisms at play in anterior knee pain. However, in this clinical commentary, Wilson raises considerable questions regarding it's usefulness as a diagnostic tool

• Contrary to popular belief, the existence of patellar malalignment in subjects with PFPS is uncertain. In fact, the weight of evidence currently suggests otherwise.


• The non radiological clinical tests most commonly used have been shown to be lacking appropriate scientific qualities and have been deemed clinically unacceptable.


• Until more scientifically robust measurements have been developed, we should be aware that many of our beliefs with regard to the role of patellar malalignment in the etiology of PFPS are based largely on assumptions and not on evidence. (Wilson, 2007)
  

If the diagnosis of a patellar malalignment is found to indeed lack clinical utility, shouldn't this also cast equal doubt on the mechanisms surrounding treatments designed to alter the supposed malalignment? Many of us "stretch" the ITB and lateral peripatellar retinacular tissue and "strengthen" the medial quadriceps in an effort to normalize this malalignment, but what if patellar malalignment is not the problem to begin with?

We know many of our treatments seem to lead to positive outcomes for our patients, but we seem to have a long road toward understanding the physiologic mechanisms surrounding the improvements. The solution to conservative management of anterior knee syndromes will likely begin by establishing clear operational diagnostic criteria. This makes a stronger case for continually refining and sharpening our clinical skill set.

Wilson, T. (2007). The Measurement of Patellar Alignment in Patellofemoral Pain Syndrome: Are We Confusing Assumptions With Evidence?. Journal of Orthopaedic and Sports Physical Therapy DOI: 10.2519/jospt.2007.2281

TKR: How much motion should we expect?

I'm not sure how this happens, but certain diagnoses seem to come to my clinic in clusters. I see a fair amount of primary TKR in my clinic. For the most part, patients undergoing primary arthroplasty seem to do very well in our clinic subjectively and functionally. Fortunately for all of us, I doubt my outcomes far exceed or lag behind many of you treating the same population.

In spite of the numerous successes we see with primary knee arthroplasty, you may share my frustration with those patients who do not fair so well following this procedure. Although many variables often contribute to a poor functional outcomes, few are as fundamental to a patient's recovery as restoration of adequate ROM. Restoring functional ROM following arthroplasty can often be a routine issue for patients and therapists, but there is an unfortunate minority who are not so fortunate.

Today's research again comes from our colleagues in orthopedic surgery. The article's authors are examine the various factors that contribute to less-than-optional ROM following primary and revision TKR.

Ritter and colleagues recently published an article in The Journal of Arthroplasty retrospectively examined 5622 TKA performed on 3672 patients between 1972 and 2002. The relationships between preoperative and postoperative flexion contracture, pain scores, functional scores, gait speed and stair climbing ability were examined using logistic regression analysis.

Noteworthy findings of this study were:

• The severity of the postoperative flexion contracture strongly correlated with the severity of the preoperative flexion contracture for moderate to severe contractures of 20 degrees or more.
• A mild (5-19 degree) preoperative flexion contracture had only a small effect on pain and functional scores. The authors explain this by the fact that many small knee flexion contractures are corrected intraoperatively.
• A preoperative hyperextension of more than 10 degrees had a negative effect on postoperative pain and functional scores. The authors do not provide explanation for this finding.

An earlier study also performed by Ritter and colleagues attempted to predict postoperative ROM after revision TKA using cluster and log-linear regression analyses. The variables used to predict ROM were preoperative flexion, intraoperative flexion, preoperative alignment, patient demographics, type of posterior soft-tissue release, previous prosthesis type, and revision prosthesis. For this study, 355 revision arthroplasties were examined with the following findings:

• Preoperative and intraoperative flexion were the most important variables predicting postoperative flexion
• Constrained and hinged prostheses had a negative effect on postoperative flexion.

The authors conclude that a patient with high preoperative flexion, middle aged or older, with a nonconstrained prosthesis has the best predicted postoperative flexion. Conversely, low preoperative flexion, younger age, and constrained prostheses had the worst postoperative flexion. Improvements in flexion following a revision were lower than following a primary TKR.

What can these studies tell us?

After wading through the data of these two article, a few important take home messages came to mind. One is the compelling case for preoperative physical therapy for primary and revision TKR. With the right approach, a well-trained therapist should be able to partially address preoperative ROM deficits.

Secondly, these papers lend support to not simply breezing through the history of a patient with a TKR. Factors such as age, preoperative ROM, and even knowing the prosthesis type may provide valuable information for you regarding your patient's rehab potential. I hope you find this summary helpful and as always welcome your questions, comments, and contributions.

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RITTER, M., LUTGRING, J., DAVIS, K., BEREND, M., PIERSON, J., MENEGHINI, R. (2007). The Role of Flexion Contracture on Outcomes in Primary Total Knee Arthroplasty. The Journal of Arthroplasty, 22(8), 1092-1096. DOI: 10.1016/j.arth.2006.11.009

Ritter, M. (2004). Predicting range of motion after revision total knee arthroplasty Clustering and log-linear regression analyses . The Journal of Arthroplasty, 19(3), 338-343. DOI: 10.1016/j.arth.2003.11.001