The adult joint-reconstruction community has made great strides in the last 2 decades in understanding what causes aseptic loosening of arthroplasty components. For example, revelations about polyethylene particulate debris has led to the production of highly cross-linked polyethylene, which in turn has lowered wear rates, decreased revision rates, and increased the survivorship of total hip implants (see related OrthoBuzz post). Still, polyethylene debris is only one factor that can lead to aseptic loosening. Another important, yet often overlooked, factor is friction between the impacted acetabular shell and the host bone.
In the October 3, 2018 issue of The Journal, Bergmann et al. report data that help us better understand the “friction factor” in aseptic loosening. The authors implanted specially designed, instrumented acetabular components that measured in vivo friction moments among nine patients while they engaged in >1,400 different activities. The authors found that 124 of those activities led to friction moments >4 Nm—which appears to be the upper limit for facilitating a firm union between the acetabular component and the native socket.
Movements such as muscle stretching in the lunge position, the breaststroke in swimming, 2-legged standing with muscles contracted, and a single-legged stance while moving the contralateral leg were among those that created the highest friction between the implant and the host bone—and that could impede bone ingrowth into the acetabular component and thus contribute to aseptic loosening. The study also highlights the importance of periodic unloading of the prosthetic joint to allow proper synovial lubrication, which helps minimize the effects of high-friction moments. The good news is that the vast majority of activities studied do not appear to result in friction forces above the 4 Nm threshold.
Although these data should be confirmed with other in-vivo instrumented prostheses (assuming there are more patients willing to receive acetabular components capable of delivering telemetric data), they provide practical insight into the real-world forces placed on total hip prostheses after implantation. Such information can be used to counsel patients regarding high-friction and sustained-loading activities to be avoided, and it can help physical therapists and surgeons tailor postoperative regimens that optimize patient recovery while minimizing the risk to implanted prostheses.
Marc Swiontkowski, MD
An estimated 300,000 ACL surgeries are performed in the US annually, at an estimated cost of up to $1 billion, but we still have many unanswered questions about patient satisfaction after these procedures. Among them:
- Does the cost of postoperative physical therapy affect patient satisfaction?
- What are the rates and predictors of return to play after ACL reconstruction? Does graft choice play a role?
- What is the relationship between return to play and patient satisfaction?
On Wednesday, December 13, 2017 at 8:00 PM EST, the Journal of Orthopaedic & Sports Physical Therapy (JOSPT) and The Journal of Bone & Joint Surgery (JBJS) will host a complimentary* LIVE webinar that addresses these and other important questions.
JOSPT co-author Caitlin J. Miller, PT, DPT and JBJS co-author Benedict U. Nwachukwu, MD, MBA, will discuss findings from their respective studies, and the webinar will include additional insights from Mark V. Paterno, PT, PhD, MBA, SCS, ATC, and Elizabeth Matzkin, MD. Moderated by Tara Jo Manal, PT, DPT, OCS, SCS, FAPTA, the webinar will conclude with a live Q&A session between the audience and panelists.
Seats are limited so REGISTER NOW.
*All registrants will have free access to the webinar for 24 hours following the live broadcast.
Many orthopaedic surgeons still believe that physical therapy (PT) services simply add to the total cost of care without improving patient outcomes. During my orthopaedic education, several knowledgeable attending surgeons said patients can be shown exercises in the orthopaedic clinic and do them on their own to avoid the increased expense of PT services. This belief extended to preoperative PT (“prehab”) to prepare patients for joint-replacement procedures. Until now, the impact of prehab on the total cost of care had not been rigorously evaluated.
In a well-designed study in the October 1, 2014 edition of The Journal, Snow et al. investigated whether preoperative PT affected total episode-of-care cost for hip- and knee-replacement procedures. They used CMS (Centers for Medicare & Medicaid Services) data from 169 urban and rural hospitals in Ohio and gleaned 4733 complete records to answer the question. The outcome measures of interest were utilization of post-acute care in the first 90 days after the procedure and total episode-of-care costs. The study defined post-acute care as admission to a skilled nursing facility, use of inpatient rehabilitation services, or use of home health services.
Nearly 80% of patients who did not receive preoperative PT services utilized post-acute care services, compared with 54% of patients who did receive prehab services. This resulted in a mean cost reduction of $871 per episode (after adjusting for age and comorbidities), with much of the savings accruing from decreased use of skilled nursing facilities. In their discussion, the authors note that prehab in this study generally consisted of only one or two sessions, and they therefore suggest that “the value of preoperative physical therapy was primarily due to patient training on postoperative assistive walking devices, planning for recovery, and managing patient expectations, and not from multiple, intensive training sessions to develop strength and range of motion.”
So it seems that prehab can reduce the overall cost of care in the setting of joint replacement. Further investigations using commercial insurance datasets to supplement this CMS data will be useful in developing treatment protocols and policies in this age of global payments for episodes of care.
Marc Swiontkowski. MD, Editor-in-Chief, JBJS
The medical landscape is always changing. With the Affordable Care Act, implementation of ICD-10, and penalties for not participating in the Physician Quality Reporting System (PQRS), practices have a lot of challenges ahead.
To help meet those challenges, orthopaedic surgeon Thomas C. Barber, chair of the AAOS Council on Advocacy, recommends that practices consider expanding ancillary services such as MRI or physical therapy. He also advises that practices should bill for all services rendered and use marketing and enhanced relationships with referring physicians to solidify their business. Finally, astutely observe the trends in your local health care community, such as ACO formation and changes in surgeon/hospital relationships. Barber says that understanding your practice’s economics and local environment will help you see opportunities for merging or collaborating with other practices.