Low back pain hinders knee replacement recovery
medwireNews: Patients with symptomatic low back pain (LBP) have a worse outcome 2 years after total knee arthroplasty than those not suffering from such coexisting pain, study findings show.
The study demonstrated that total knee arthroplasty greatly improved functional outcomes in patients with and without LBP. But patients with LBP had Oxford Knee Scores (OKS) that were a significant 5 points lower after surgery than those for patients without back pain, and these patients scored a significant 6 points lower for general physical health on the SF-12.
Also, patients with LBP showed no improvement in overall mental health, unlike those without such pain.
“Therefore patients with chronic LBP should be counselled, pre-operatively, that their outcome after surgery may be sub-optimal,” say lead researcher Mark Blyth and colleagues, from Glasgow Royal Infirmary in the UK.
The preoperative OKS was a median 15 for the 40 patients with LBP and 16 for the 305 without back pain. Post surgery, these scores improved to 31 and 36, respectively, but the difference was significantly greater for those without back pain.
The findings were similar for American Knee Society Scores, although the difference between those with and without back pain was more marginal.
The preoperative SF-12 Physical Health scores were a median 27 for patients with LBP and 28 for those without, and increased to 34 and 40, respectively, while SF-12 Mental Health scores improved from a respective 50 to 53 in patients without back pain, but decreased from 51 to 48 in those with LBP.
The researchers note in The Knee that, by contrast, musculoskeletal pathology at the hip or ankle had no effect on functional outcome. They say that it is unclear whether this is due to these pathologies being less disabling or LBP having a greater pain-sensitising effect.
LBP was also associated with a significantly higher rate of revisions, after excluding those due to infections and unlikely to be related to LBP, at 7.5% versus 1.0%.
Although unable to give a definitive reason for this difference, the researchers say that, “given the high proportion of pain catastrophising reported in patients group with LBP[,] it is possible that this group of patients may have a lower tolerance or threshold for pain associated with their new joint and therefore these patients may seek earlier intervention”.
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2014
By Lucy Piper, Senior medwireNews Reporter