Is there a rational basis for post-surgical lifting restrictions? 2. Possible scientific approach

Abstract

IntroductionAfter surgery it is a common practice to prescribe lifting restrictions. In a companion paper [38] we demonstrated that, in practice, there is no consistency in these restrictions. The restrictions appear to be based on a premise that the spine is weaker and thus subject to re-injury when there has been some disruption of the functional spinal motion unit (FSU) due to surgery. However re-injury is seldom reported in the literature and restrictions do affect return to work [37, 42].From a biomechanical standpoint, the spine is an unstable structure without proper functioning of the paraspinal musculature. A lumbar spine, stripped of muscle, will buckle under compressive loads as low as 90 N. Other structures, which could be modified by surgery, are important. The basic shape of the vertebrae, especially the configuration of the facet joints, also add to the stabilization of the FSU. Panjabi's seminal contributions have delineated the specific role of reach FSU structure [53][54][55][56][57][58][59][60][61].Posture is most important in the risk for low back pain (LBP) and herniated nucleus pulposus (HNP). In one study, positive associations were also seen for frequent lifting with arms extended (relative risk, RR = 1.87) and twisting while lifting (RR = 1.90). Increased risk of HNP has been associated with lifting while twisting [32]. Lifting with knees straight and back bent increased the risk of Abstract Lifting restrictions postoperatively are quite common but there appears to be little scientific basis for them. Lifting restricitions are inhibitory in terms of return to work and may be a factor in chronicity. The mean changes in functional spinal motion unit (FSU) stiffness with in vitro or computer-simulated discectomies, facetectomies and laminectomies were reviewed from the literature. We modified the NIOSH lifting equation to include another multiplier related to stiffness change post surgery. The new recommended lifts were computed for different lifting conditions seen in industry. The reduction of rotational stiffness ranged from 21% to 41% for a discectomy, 1% to 59% for a facetectomy and 4% to 16% for a partial laminectomy. The recommended lifts based on our modified equation were adjusted accordingly. There is no rational basis for current lifting resctrictions. The risk to the spine is a function of many other variables as well as weight (i.e., distance of weight from body). The adjusted NIOSH guidelines provide a reasonable way to estimate weight restrictions and accomodations such as lifting aids. Such resitrictions should be as liberal as possible so as to facilitate, not prevent, return to work. Patients need more advice regarding lifting activities and clinicians should be more knowledgeable about the working conditions and constraints of a given workplace to effectively match the solution to the patient's condition.Key words Lifting · Surgery · Return to work · Low back pain · NIOSH ORIGINAL ARTICLE Eur Spine J (1999) 8 : 179-186

National audit of post-operative management in spinal surgery

“…Magnusson et al . [ 21 ] were unable to identify any evidence in the literature to support such restrictions, even when mechanical factors were considered [ 22 ]. Our paper now adds evidence of a notable discordance between post-operative restrictions on sitting and recommendations about return to sedentary work or driving.…”

Is there a rational basis for post-surgical lifting restrictions? 1. Current understanding

“…In a companion paper [67], we make suggestions for a means of considering all important aspects of lifting (weight, position, lifting rate, asymmetry) and the decreased mechanical properties due to surgery. This may prove to be a useful approach to scientifically based lifting restrictions.…”

Evaluation of the Impact of the Revised National Institute for Occupational Safety and Health Lifting Equation

“…The recommendation was to be added to accommodate “post-surgery workers” who typically have restricted lifting capabilities. The rationale for this addition was described in a subsequent paper (Pope, Magnusson, Wilder, Goel, & Spratt, 1999). To our knowledge, all the suggested revisions to the RNLE model have not been validated.…”