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Where Does the Blood Flow in the Femoral Head?

Femoral Head Vasculature.jpegOsseous vascular anatomy has always been clinically relevant to orthopaedists, but its importance is sometimes overlooked. In the July 19, 2017 issue of The Journal, Rego et al. provide a precise topographic map of arterial anatomy in and around the femoral head.

Ever since Trueta’s classic work published in the British volume of JBJS in 1953, we’ve known that the terminal branches of the medial femoral circumflex system (also known as the lateral epiphyseal artery complex) supply blood to the majority of the femoral head. This information has proved critical in supporting treatment decisions for the management of femoral head and neck fractures. In those cases, surgeons typically perform ORIF through an anterior approach because it is remote from this posterior vascular supply.

The details in the Rego et al. study will help today’s and tomorrow’s arthroscopists more safely manage acetabular labral tears associated with cam deformities. In those settings, when increasing the “offset” across the femoral neck to decrease impingement, surgeons should limit the depth of bone removal to avoid injury to this important vascular network. Thanks to this study, operating surgeons now have precise anatomic information (albeit derived from non-deformed cadaver hips) with which to limit the risks of increasing the femoral head offset.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

Centenarians Fare Pretty Well After Hip Fracture Treatment

Centenarian.jpgPeople 100 years old and older—centenarians—make up only 0.02% of the current US population. Nevertheless, the number of centenarians is expected to increase five-fold by 2060. That is in part what prompted Manoli III et al. to analyze a large New York State database to determine whether patients ≥100 years old who sustained a hip fracture fared worse in the hospital than younger hip-fracture patients. The study appears in the July 5, 2017 issue of The Journal of Bone & Joint Surgery.

Only 0.7% of the more than 168,000 patients ≥65 years old included in the analysis sustained a hip fracture when they were ≥100 years old. Somewhat surprisingly, centenarians incurred costs and had lengths of stay that were similar to those of the younger patients. However, despite those similarities, centenarians had a significantly higher in-hospital mortality rate than the younger patients. Male sex and an increasing number of comorbidities were found to predict in-hospital mortality for centenarians with hip fractures.

Manoli III et al. also found that, relative to other age groups, centenarians were managed nonoperatively at a slightly higher frequency when treated for extracapsular hip fractures. For intracapsular fractures, an increasing proportion of patients >80 years were managed with hemiarthroplasty and nonoperative treatment. Finally, among centenarians, time to surgery did not affect short-term mortality rates, suggesting a potential benefit to preoperative optimization.

The Acetabulum’s Role in SCFE: Cause or Consequence?

Acetabular Version for O'Buzz.jpegThe multifactorial pathogenesis of slipped capital femoral epiphysis (SCFE) almost certainly involves the acetabulum, but previous studies about that relationship have been inconclusive. In the June 21, 2017 issue of JBJS, Hesper et al. report on a matched-cohort study that used precise measurements gleaned from CT to determine that acetabular retroversion—not acetabular depth or overcoverage of the femoral head—is associated with SCFE.

The authors carefully measured acetabular depth, head coverage, and retroversion in three groups of hips: the affected hips of 36 patients with unilateral SCFE, the unaffected contralateral hips of those same patients, and healthy hips of 36 age- and sex-matched controls. They observed no deep acetabula or acetabular overcoverage in the SCFE-affected hips, but they did find a lower mean value for acetabular version (i.e., retroversion) at the level of the femoral-head center in the SCFE-affected hips, relative to contralateral and control hips.  The acetabulum was retroverted cranially in cases of severe SCFE compared with mild and moderate cases.

These findings support the hypothesis that SCFE-affected hips have reduced acetabular version, but the authors note that “additional studies will be necessary to determine whether acetabular retroversion is a primary morphological abnormality associated with the mechanical etiology of SCFE, or if it is an adaptive response to the acetabulum after the slip.” Either way, Hesper et al. conclude that their data “may help with planning treatment for patients with residual pain and limited motion related to femoroacetabular impingement after SCFE.

Does Hip Arthroscopy Really Help?

Menge_Image_for_O'Buzz.pngOver the past 15 to 20 years, the use of arthroscopic procedures for hip pathologies has rapidly increased. Leaders in sports medicine have standardized many arthroscopic techniques, including methods of joint distraction, portal location, approaches to labral repair or debridement, and management of cartilage lesions.

Many in the orthopaedic community have wondered whether this expansive  use of  hip arthroscopy is justified by significant improvement in patient function or is simply a first (and perhaps overused) step toward inevitable hip arthroplasty. To help answer that question, in the June 21, 2017 issue of The Journal, Menge et al. document the 10-year outcomes of arthroscopic labral repair or debridement in 145 patients who originally presented with femoroacetabular impingement (FAI).

Whether these patients were treated with debridement or repair, their functional outcomes and improvement in symptoms were excellent over the 10-year time frame, and the median satisfaction score (10) indicates that these patients were very satisfied overall. However, as seen in other similar studies in the peer-reviewed literature, the results in older patients with significant cartilage injury or radiographic joint space narrowing were inferior, and most of the patients with these characteristics ended up with a hip replacement.

The Menge et al. study helps confirm that arthroscopic repair or debridement in well-selected FAI patients yields excellent longer-term outcomes, and it provides concrete criteria for patient selection.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

Good Outcomes with After-Hours Hip Fracture Surgery

marc-swiontkowski-2In the June 7, 2017 issue of The Journal of Bone & Joint Surgery, Pincus et al. report on a careful analysis comparing outcomes from hip fracture surgery occurring “after hours” (defined by the authors as weekday evenings between 5 PM and 12 AM) with surgeries occurring during “normal hours” (weekdays from 7 AM to 5 PM). In the busy Ontario trauma center where this study was performed, it is common for patients with blunt trauma to take precedence over seniors who are relatively stable but in need of hip fracture care.

Pincus et al. found that adverse outcomes, in terms of surgical and medical complications, were similar whether the hip surgery occurred during normal hours or after hours.  Interestingly, there was a higher rate of inpatient complications in the normal-hours group, and fewer patients in the after-hours group were discharged to a rehab after surgery than in the normal-hours group.

It has been my impression that highly skilled professional surgeons and their teams are going to put forward their best efforts for all patients—no matter what time of day or night they operate. Concentration, focus, and high standards can generally overcome fatigue. However, the Pincus et al. study should not be viewed as justification for hospital decision makers to forget their commitment to optimize management of all resources, including surgical teams. After-hours care should never become “routine,” and there should be continuous attention on developing alternative solutions, such as moving elective surgery to other facilities or true shift scheduling that provides all members of the team with occasional daytime hours off for rest and management of personal lives.

The authors note that in their Canadian jurisdiction, there are hospital and surgeon-reimbursement incentives that may work to promote after-hours surgery, but the long-term focus must always put patient outcomes first. And we must always remember that good patient outcomes rely on maintaining surgical teams who are experienced and not burnt out.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

JBJS Classics: Porous-Coated Hip Components

JBJS Classics Logo.pngOrthoBuzz regularly brings you a current commentary on a “classic” article from The Journal of Bone & Joint Surgery. These articles have been selected by the Editor-in-Chief and Deputy Editors of The Journal because of their long-standing significance to the orthopaedic community and the many citations they receive in the literature. Our OrthoBuzz commentators highlight the impact that these articles have had on the practice of orthopaedics. Please feel free to join the conversation by clicking on the “Leave a Comment” button in the box to the left.

In their classic 1987 publication, Drs. Charles Engh, Dennis Bobyn, and Andrew Glassman described clinical and radiographic results of a series of 307 hips with 2-year follow-up, and 89 hips with 5-year follow-up after total hip arthroplasty in which the patients had received an extensively porous-coated femoral stem. The authors also described histologic evaluation of 11 hips retrieved at autopsy or revision.

By 1987 the same authors as well as other investigators had already published observations concerning the influence of femoral stem size, shape, stiffness, and porosity on clinical and radiographic evidence of fixation and stress shielding in humans and animal models.1,2 But this study, which so far has been cited more than 1500 times, goes “above and beyond” by carefully correlating previous observations with histologic sections obtained through human femora.

Among other achievements, Engh et al. described radiographic criteria for categorizing a femoral implant as either stable by bone ingrowth, stable by fibrous tissue ingrowth, or unstable. Implants thought to be stable by fibrous ingrowth had a prominent radio-opaque line around the stem, separated from the implant by a radiolucent space up to 1 mm in thickness. This line was thought to represent a shell of bone with load-carrying capability. However, histology demonstrated that the space between the shell and the implant was composed of dense fibrous tissue. When the shell was present, there tended to be little hypertrophy or atrophy of the adjacent femoral cortex.

Engh et al. noted that radiographs and histology of hips with extensive ingrowth from the endosteum often showed parallel increased porosity of the adjacent cortex – an early manifestation of stress shielding. Overall, 259 (84%) of the femoral stems had radiographic findings suggestive of bone ingrowth, 42 (13%) had findings interpreted as stable fibrous ingrowth, and 2% were thought to be unstable (but not yet revised at the time of the study). Stress shielding was much more common in larger-diameter stems and those with good bone ingrowth compared to smaller implants or those with stable fibrous fixation.

Why do we consider this manuscript a classic? First, the authors include a careful correlation of histology with radiographic and clinical findings, helping illustrate the importance of tight press fit at the isthmus to achieve proximal fixation. The authors also document intracortical porosity as the morphologic manifestation of stress shielding and emphasize the impact of a small increase in stem diameter on axial rigidity.

Designs of femoral stems have evolved considerably since the 1980s,3 and the findings described in this paper helped validate fundamental principles related to load transmission and bone remodeling4-6 and thus helped advance that evolutionary process.

Thomas W. Bauer, MD, PhD
JBJS Deputy Editor

References

  1. Bobyn JD, Pilliar RM, Binnington AG, Szivek JA. The effect of proximally and fully porous-coated canine hip stem design on bone modeling. Journal of orthopaedic research : official publication of the Orthopaedic Research Society 1987;5:393-408.
  2. Bobyn JD, Pilliar RM, Cameron HU, Weatherly GC. The optimum pore size for the fixation of porous-surfaced metal implants by the ingrowth of bone. Clinical orthopaedics and related research 1980:263-70.
  3. McAuley JP, Culpepper WJ, Engh CA. Total hip arthroplasty. Concerns with extensively porous coated femoral components. Clinical orthopaedics and related research 1998:182-8.
  4. Huiskes R. Validation of adaptive bone-remodeling simulation models. Stud Health Technol Inform 1997;40:33-48.
  5. Huiskes R, Weinans H, Dalstra M. Adaptive bone remodeling and biomechanical design considerations for noncemented total hip arthroplasty. Orthopedics 1989;12:1255-67.
  6. Weinans H, Huiskes R, Grootenboer HJ. Effects of fit and bonding characteristics of femoral stems on adaptive bone remodeling. J Biomech Eng 1994;116:393-400.

June 2017 Article Exchange with JOSPT

JOSPT_Article_Exchange_LogoIn 2015, JBJS launched an “article exchange” collaboration with the Journal of Orthopaedic & Sports Physical Therapy (JOSPT) to support multidisciplinary integration, continuity of care, and excellent patient outcomes in orthopaedics and sports medicine.

During the month of June 2017, JBJS and OrthoBuzz readers will have open access to the JOSPT article titled “The Association of Recreational and Competitive Running With Hip and Knee Osteoarthritis: A Systematic Review and Meta-analysis.”

Based on 17 studies included in the meta-analysis, the authors found that recreational runners had a lower occurrence of osteoarthritis compared with competitive runners and sedentary controls.

Sports Medicine Update

What's_New_Sports_Med_Image_for_O'Buzz.pngEvery month, JBJS publishes a Specialty Update—a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of all OrthoBuzz Specialty Update summaries.

The May 17, 2017 JBJS Specialty Update on Sports Medicine reflects evidence in the field of sports medicine published from September 2015 to August 2016. Although this review is not exhaustive of all research that might be pertinent to sports medicine, it highlights many key articles that contribute to the existing evidence base in the field.

Topics covered include:

  • Prevention of Musculoskeletal Injuries
  • Autograft vs Allograft ACL Reconstruction
  • Anterior Shoulder Stabilization
  • Hip Arthroscopy

Fracture Liaison Service Boosts Patient Engagement with Secondary Prevention

fragility fractures for O'Buzz.pngOrthoBuzz has published several posts about osteoporosis, fragility fractures, and secondary fracture prevention. In the May 17, 2017 edition of JBJS, Bogoch et al. add to evidence suggesting that a coordinator-based fracture liaison service (FLS) improves engagement with secondary-prevention practices among inpatients and outpatients with a fragility fracture.

The Division of Orthopaedic Surgery at the University of Toronto initiated a coordinator-based FLS in 2002 to educate patients with a fragility fracture and refer them for BMD testing and management, including pharmacotherapy if appropriate. Bogoch et al. analyzed key clinical outcomes from 2002 to 2013 among a cohort of 2,191 patients who were not undergoing pharmacotherapy when they initially presented with a fragility fracture.

  • Eighty-four percent of inpatients and 85% of outpatients completed BMD tests as recommended.
  • Eighty-five percent of inpatients and 79% of outpatients who were referred to follow-up bone health management were assessed by a specialist or primary care physician.
  • Among those who attended the referral appointment, 73% of inpatients and 52% of outpatients received a prescription for anti-osteoporosis medication.

The authors conclude that “a coordinator-based fracture liaison service, with an engaged group of orthopaedic surgeons and consultants…achieved a relatively high rate of patient investigation and pharmacotherapy for patients with a fragility fracture.”

More Comparative Data on Surgical Approaches to THA

Implant Survival and THA Approach.jpegThe May 17, 2017 edition of The Journal of Bone & Joint Surgery features a registry-based study by Mjaaland et al. comparing implant-survival/revision outcomes in total hip arthroplasty (THA) among four different surgical approaches:

  • Minimally Invasive (MI) Anterior (n=2017)
  • MI Anterolateral (n=2087)
  • Conventional Posterior (n=5961)
  • Conventional Direct Lateral (n=11,795)

Although the authors analyzed a whopping 21,860 THAs from 2008 to 2013, the findings are limited by the fact that all of those procedures used an uncemented stem.

Overall, the revision rates and risk of revision with the MI approaches were similar to those of the conventional approaches. There was a higher risk of revision due to infection in THAs that used the direct lateral approach than in THAs using the other three approaches. “To our knowledge,” the authors write, “this finding has not been previously described in the literature, and we do not have an explanation for it.” The authors also found a reduced risk of revision due to dislocation in THAs that used the MI anterior, MI anterolateral, and direct lateral approaches, relative to those using the posterior approach.

While the authors found all-cause risk of revision to be similar among all four approaches, they note that the follow-up in the study was relatively short (mean of 4.3 years) and that “additional studies are needed to determine whether there are long-term differences in implant survival.”