Rehabilitation outcome after total hip replacement
Abstract af Mette Krintel Petersen
Total hip replacement (THR) has evolved into a reliable and suitable surgical procedure to relieve pain and restore function among patients with damaged or degenerated hip joints and chronic pain.
The longevity of currently available implants is often considered as the main outcome after THR. However, outcome after THR depends not merely on a successful surgical procedure, but also on adequate postoperative rehabilitation. Multimodal rehabilitation, which evolved as a coordinated multimodal effort combining modern concepts of patient care with multimodal anesthetic and analgesic methods, has been introduced to improve rehabilitation after surgery.
The evolution of THR has been aided by information generated from gait analysis studies. Design criteria based on load magnitudes generated during gait have been used for both failure analysis as well as wear testing of new implants. A key to analysis of function following joint replacement is the ability to identify gait adaptations specific to design features.
The aims of this PhD thesis were in randomized controlled designs to evaluate rehabilitation outcome aspects after THR in terms of I) evaluating whether mobilization and nutrition could be optimized during admission, and if so to assess the effects on rehabilitation, II) evaluating the external validity of study I, III) evaluating the efficacy of optimized perioperative care on late phase rehabilitation outcome after THR, IV) evaluating mechanics of gait after THR with two different types of implants.
In study I, we evaluated 79 prospectively randomized patients undergoing elective primary THR. One group received optimized perioperative care (OPC); another group received conventional perioperative care (CPC). Epidural-spinal anesthesia and postoperative epidural analgesia with local anesthetics and opioids were used in all cases. Rehabilitation outcome was measured by length of stay (LOS), and process indicators were mobilization and nutrition. Although mobilization and energy intake were significantly increased in the OPC group compared with CPC group, LOS was moderately reduced (P=0.02). No differences in complications or readmission were seen.
In study II, we studied the distribution of preoperative characteristics and postoperative clinical variables among non-consenters and consenters in study I. In the randomized controlled trial (RCT), 130 patients were identified as potential participants, 18 patients were excluded, 33 enrolled participants declined to participate (non-consenters).
Significant differences were found in both preoperative characteristics and clinical outcome variables. The non-consenters were older, less healthy, and needed more help from the home care system. Furthermore, they were hospitalized longer and were more often transferred to a rehabilitation ward.
In study III, we evaluated the efficacy of two different peri-operative regimes after THR on self-reported functional outcome in 79 prospectively randomized patients. Rehabilitation outcome was measured by the 36-Item Short Form Health Survey (SF -36) and the Western Ontario and McMasters University Osteoarthritis Index (WOMAC). Patients’ functional status 6 months postoperatively were compared with an age- and gender-matched healthy cohort. A representative sample of 4098 non-institutionalized Danish adults collected by the Danish National Institute of Public Health was used as controls.
We found similar improvements in SF-36 and WOMAC scores in the OPC group and the CPC group postoperatively, except for the total WOMAC score and the WOMAC sub-score function, which were statistically better in the CPC group. OPC and CPS group were similar with respect to score level. Six months after surgery, THR patients scored higher in the general health sub-scale and lower in three physical sub-scales of SF-36 [(P=
In study IV, we evaluated 30 prospectively randomized patients undergoing elective primary THR. One group received Hip Resurfacing System (HRS) implant; another group received Mallory-Head Exeter (MHE) prosthesis. To examine whether one implant was superior to the other we evaluated mechanics of gait 6 and 12 weeks postoperatively. We also investigated whether gait adaptation normalized postoperatively. Laboratory three dimensional (3D) gait analyses were performed 6 and 12 weeks postoperatively. To compare patients with healthy controls, we used data from 22 age- and gender- matched healthy controls.
We found similar postoperative improvements in mechanics of gait between the groups except for the peak abductor moments which changed more in the MHE group. HRS and MHE groups were similar with respect to level of peak values. Three months after surgery, most peak values were significantly different between the operated and non-operated hip in all THR patients. Mean curves of kinetic and kinematic variables of THR patients and healthy controls showed that gait adaptations were not normalized after 3 months.
Compared with conventional care, multimodal rehabilitation resulted in a moderate reduction in LOS. We found no differences between groups in relation to complications or pain.
Because the non-consenters did not include patients with contra indications for therapy, our data reinforce the need to provide additional information about recruitment process supplemented with readily available data in order to avoid biased estimates of treatments effects and misleading assessments regarding the degree to which the results may be generalized.
No evidence was found that enforced mobilization and nutrition during admission could affect self-reported functional outcome measured by SF-36 and WOMAC.
We found no evidence that dynamic range of motion (ROM) and muscle strength could be more affected in the early phase of rehabilitation and persisting impairments less in patients receiving a resurfacing implant compared with patients receiving a conventional prosthesis.
Although, THR patients improved considerably impairments in physical functioning and gait adaptation persisted.