Anterior Knee Pain - Post Replacement
Today we are going to talk a little bit about knee pain after a knee replacement and we have found some interesting research papers about it, so let’s see what this anterior knee pain is and how we can treat it.
First of all, they concluded that anterior knee pain after a knee replacement could be a multifactorial problem and this pain is caused by soft tissues being overloaded and/or mechanical causes like instability or femoral or tibial rotations.(1)
But… is it normal to feel pain after a knee replacement? According with Brander et al and Forsythe et al the “natural” course of pain after uncomplicated knee replacement is the next:
On scale from 0 to 100, the pain level dropped from an average of 52 points to 25 points after three months and after one year the pain level was still at an average of 17 points. According to these findings, Forsythe et al concluded in another research project that pain intensity decreased from 68 point to 33 after 3 months and the pain level after a year was 22. (2,3)
So…what can cause the anterior knee pain after a knee replacement?
We can divide pain’s cause in two different types:
Functional causes:
Quadriceps muscle weakness: Many patients after knee replacement present with a “quadricep
s avoidance gait”. It is also known that imbalance of the quadriceps with weakness of the vastus medialis and increased activation of the vastus lateralis muscle can cause a lateral maltracking of the patella.
Dynamic valgus affects the femoropatellar joint because it leads to lateral patellar maltracking.
Gluteus medius weakness.(4,5)
Some patients also have co-morbidities of the lumbar spine, increasing stress on the femoropatellar joint.
Pic 1.Dynamic valgus
Mechanical causes:
These factors are patello-femoral instability, prosthesis design, patella baja, chondrolysis, offset error of the femoral component rotational error, tibiofemoral instability, avascular necrosis and synovial hyperplasia. All of these causes can lead to pain and functional deficits of patients with anterior knee pain after knee replacement.
And now, the most important question… what should I do when I feel pain after knee replacement? Will I need another surgery?
Although therapy of anterior knee pain after knee replacement depends on the causes, pain intensity and functional impairment, conservative treatment for functional causes and mechanical causes is the treatment of choice. Only in certain cases, when the pain is due of mechanical causes, surgery treatment is necessary (6).
In conclusion:
Anterior knee pain after knee replacement is a multifactorial problem.
We can divide pain’s cause in two different types; functional and mechanical.
In the majority of the cases conservative treatment for both causes is the treatment of choice.
BIBLIOGRAPHY:
1. Breugem SJM, Haverkamp D. Anterior knee pain after a total knee arthroplasty: What can cause this pain? World J Orthop. 2014 Jul 18;5(3):163–70.
2. Brander VA, Stulberg SD, Adams AD, Harden RN, Bruehl S, Stanos SP, et al. Predicting total knee replacement pain: a prospective, observational study. Clin Orthop Relat Res. 2003 Nov;(416):27–36.
3. Forsythe ME, Dunbar MJ, Hennigar AW, Sullivan MJL, Gross M. Prospective relation between catastrophizing and residual pain following knee arthroplasty: two-year follow-up. Pain Res Manag. 13(4):335–41.
4. Barton CJ, Lack S, Malliaras P, Morrissey D. Gluteal muscle activity and patellofemoral pain syndrome: a systematic review. Br J Sports Med. 2013 Mar;47(4):207–14.
5. Prins MR, van der Wurff P. Females with patellofemoral pain syndrome have weak hip muscles: a systematic review. Aust J Physiother. 2009;55(1):9–15.
6. Petersen W, Rembitzki IV, Brüggemann G-P, Ellermann A, Best R, Koppenburg AG-, et al. Anterior knee pain after total knee arthroplasty: a narrative review. Int Orthop. 2014 Feb 22;38(2):319–28.
