Brian T. Barlow

Does Degenerative Lumbar Spine Disease Influence Femoroacetabular Flexion in Patients Undergoing Total Hip Arthroplasty

BackgroundSitting pelvic tilt dictates the proximity of the rim of the acetabulum to the proximal femur and, therefore, the risk of impingement in patients undergoing total hip arthroplasty (THA). Sitting position is achieved through a combination of lumbar spine segmental motions and/or femoroacetabular articular motion in the lumbar-pelvic-femoral complex. Multilevel degenerative disc disease (DDD) may limit spine flexion and therefore increase femoroacetabular flexion in patients having THAs, but this has not been well characterized. Therefore, we measured standing and sitting lumbar-pelvic-femoral alignment in patients with radiographic signs of DDD and in patients with no radiographic signs of spine arthrosis.Questions/purposesWe asked: (1) Is there a difference in standing and sitting lumbar-pelvic-femoral alignment before surgery among patients undergoing THA who have no radiographic signs of spine arthrosis compared with those with preexisting lumbar DDD? (2) Do patients with lumbar DDD experience less spine flexion moving from a standing to a sitting position and therefore compensate with more femoroacetabular flexion compared with patients who have no radiographic signs of arthrosis?MethodsThree hundred twenty-five patients undergoing primary THA had preoperative low-dose EOS spine-to-ankle lateral radiographs in standing and sitting positions. Eighty-three patients were excluded from this study for scoliosis (39 patients), spondylolysis (15 patients), not having five lumbar vertebrae (7 patients), surgical or disease fusion (11 patients), or poor image quality attributable to high BMI (11 patients). In the remaining 242 of 325 patients (75%), two observers categorized the lumbar spine as either without radiographic arthrosis or having DDD based on defined radiographic criteria. Sacral slope, lumbar lordosis, and proximal femur angles were measured, and these angles were used to calculate lumbar spine flexion and femoroacetabular flexion in standing and sitting positions. Patients were aligned in a standardized sitting position so that their femurs were parallel to the floor to achieve approximately 90° of apparent hip flexion.ResultsAfter controlling for age, sex, and BMI, we found patients with DDD spines had a mean of 5° more posterior pelvic tilt (95% CI, −2° to −8° lower sacral slope angles; p < 0.01) and 7° less lumbar lordosis (95% CI, −10° to −3°; p < 0.01) in the standing position compared with patients without radiographic arthrosis. However, in the sitting position, patients with DDD spines had 4° less posterior pelvic tilt (95% CI, 1°–7° higher sacral slope angles; p = 0.02). From standing to sitting position, patients with DDD spines experienced 10° less spine flexion (95% CI, −14° to −7°; p < 0.01) and 10° more femoroacetabular flexion (95% CI, 6° to 14°; p < 0.01).ConclusionsMost patients undergoing THA sit in a similar range of pelvic tilt, with a small mean difference in pelvic tilt between patients with DDD spines and those without radiographic arthrosis. However, in general, the mechanism by which patients with DDD of the lumbar spine achieve sitting differs from those without spine arthrosis with less spine flexion and more femoroacetabular flexion.Clinical RelevanceWhen planning THA, it may be important to consider which patients sit with less posterior pelvic tilt and those who rotate their pelvises forward to achieve a sitting position, as both mechanisms will limit or reduce the functional anteversion of the acetabular component in a patient with a THA. Our study provides some additional perspective on normal relationships between pelvic tilt and femoroacetabular flexion, but further research might better characterize this relationship in outliers and the possible implications for posterior instability after THA.

Stem length in revision total knee arthroplasty.

Stems are intramedullary extensions of either the femoral or tibial component of a total knee arthroplasty (TKA) designed to increase the mechanical stability to decrease the risk of aseptic loosening. Biomechanical studies have shown that TKA stems increase the mechanical stability by transferring load over a larger area and thereby reduce strain at the bone-component interface [1–4]. The length of a revision TKA stem is determined by the patient’s anatomy and the intended fixation, namely fully cemented or press-fit cortical contact. The advantages and disadvantages of various stem lengths must be weighed against the needs of the patient to achieve an optimal outcome.

Magnetic Resonance Imaging Predicts Adverse Local Tissue Reaction Histologic Severity in Modular Neck Total Hip Arthroplasty

BACKGROUND The association between advanced imaging, serum metal ion levels, and histologic adverse local tissue reaction (ALTR) severity has not been previously reported for Rejuvenate modular neck femoral stems. METHODS A cohort of 90 patients with 98 Rejuvenate modular neck femoral stems was revised by a single surgeon from July 2011 to December 2014. Before revision, patients underwent multiacquisition variable resonance image combination sequence magnetic resonance imaging (MRI), and serum cobalt and chromium ion levels were measured. Histologic samples from the revision surgery were scored for synovial lining, inflammatory infiltrate, and tissue organization as proposed by Campbell. Regression based on the generalized estimating equations approach was used to assess the univariate association between each MRI, demographic, and metal ion measure and ALTR severity while accounting for the correlation between bilateral hips. Random forest analysis was then used to determine the relative importance of MRI characteristics, demographics, and metal ion levels in predicting ALTR severity. RESULTS Synovial thickness as measured on MRI was found to be the strongest predictor of ALTR histologic severity in a recalled modular neck femoral stem. CONCLUSION MRI can accurately describe ALTR in modular femoral neck total hip arthroplasty. MRI characteristics, particularly maximal synovial thickness and synovitis volume, predicted histologic severity. Serum metal ion levels do not correlate with histologic severity in Rejuvenate modular neck total hip arthroplasty.

Total Hip Arthroplasty in a Patient with Multicentric Carpotarsal Osteolysis: a Case Report.

Multicentric carpotarsal osteolysis (MTCO) syndrome is a rare skeletal disorder characterized by osteolysis, or bone resorption, particularly affecting the carpal and tarsal bones. It is frequently associated with generalized osteoporosis, scoliosis, and protrusio acetabuli, with destruction of larger joints including the elbows and hips, and can be associated with progressive renal failure [3, 14, 17]. Because its initial presentation typically includes joint pain and swelling that can mimic symptoms of juvenile idiopathic arthritis (JIA), patients may bemisdiagnosed and treated with anti-rheumatic therapy, which has no effect on the progressive joint destruction [17]. This autosomal dominant disorder is attributed to missense mutations in the gene for MAFB (v-maf musculoaponeurotic fibrosarcoma oncogene ortholog B), a transcription factor that plays an important role in bone remodeling through the regulation of osteoclast generation [18]. Osteoclasts are multinucleated cells formed by fusion of mononuclear precursors of the monocyte/macrophage lineage at or near the bone surface, and they have the important function of bone resorption [2]. One of the cytokines essential for the development and activation of osteoclasts is receptor activator of nuclear factor kB ligand (RANKL), which is expressed on the surface of osteoblasts and other cells and binds to RANK, a transmembrane receptor on the surface of osteoclasts and their precursors [1, 2]. Normally, MAFB inhibits osteoclast generation mediated by RANKL; however, this negative control is lost in MAFB mutations, leading to increased osteoclastogenesis and bone resorption [1, 18]. Therapy using anti-RANKL antibody to treat MCTO has been proposed but its use in this setting has not been reported in the literature. Since the initial discovery of mutations of the MAFB gene, additional cases confirmed by genetic testing have been reported [6, 9, 11, 13]. The literature regarding surgical management for severe osteolysis is sparse [4, 9]. We here report a case of an adolescent patient with MTCO undergoing complicated hip replacement surgery.

CORR Insights®: What Factors Predict Conversion to THA After Arthroscopy?

H ip arthroscopy is being used with increasing frequency in adults, growing by 600% in American Board of Surgery Part II examinees between 2006 and 2010 [3]. At least part of this enthusiasm for hip arthroscopy is driven by early reports demonstrating high levels of return to sport, low complication rates, and rare THA conversion in high-level and professional athletes who underwent arthroscopic surgery for labral injuries and femoroacetabular impingement (FAI) [4, 13]. But as the indications for hip arthroscopy broadened, the frequency of THA conversion increased [1, 17]. In fact, a recent populationbased study reported that 12% of hips treated arthroscopically underwent conversion to THA at 2-year followup [15]. A systematic review of more than 6000 hip arthroscopies undertaken primarily for labral repair and FAI correction also found that nearly 3% underwent THA conversion at a mean of 16 months [8]. Long-term studies found even more sobering results than the early short-term studies of highlevel athletes. The 10-year THA-free survivorship was 63% in a cohort of 340 hip arthroscopy patients [9]. Results of arthroscopic labral repair in older patients, especially those with arthritis or chondral injury have been unfavorable. The THA conversion rate in older patients with underlying chondral injury or arthritis approaches 20% to 30% in the initial year after arthroscopy and more than 80% with longer followup [5, 16]. Age, chondroplasty, decreased joint space (< 2 mm), and underlying arthritis have been found to be independent risk factors for THA conversion after hip arthroscopy [5, 8, 15, 16]. THA conversions following hip arthroscopy often occur early. Bedard and colleagues [1] found that 36% of THA conversions occurred within 6 months, 60% within 1 year, and 100% within 4 years following hip arthroscopy, again noting that age > 50 years of age and chondroplasty increased the risk for THA conversion. The fact that the majority of THA conversions occur so soon after arthroscopic surgery suggests that there are patient, imaging, and operative factors that can be used to identify and quantify risk of complications. These patients are likely better served with continued nonsurgical care until they meet indications for arthroplasty [2]. CORR Insights Published online: 11 August 2017 The Association of Bone and Joint Surgeons1 2017

Reply to the Letter to the Editor: Does Degenerative Lumbar Spine Disease Influence Femoroacetabular Flexion in Patients Undergoing Total Hip Arthroplasty?

To the Editor We would like to thank Lan and colleagues for their comments. They correctly highlighted a number of studies suggesting that spinopelvic alignment may become an important consideration for both spine and arthroplasty surgeons, particularly in patients that have both degenerative disc disease and hip osteoarthritis. While we considered pelvic incidence values in the patients included in our study, we did not incorporate this information because we wanted to focus on spinopelvic alignment in functional positions such as standing and sitting. Since pelvic incidence is not affected by posture, we relied on sacral slope as a measure of the change in pelvic orientation that occurs when moving from the standing to sitting position. We agree that pelvic incidence and other global sagittal parameters may be an important consideration, and we will consider its inclusion in future studies. We also agreewith authors of the letter that MRI is the gold standard for evaluating lumbar disc degeneration (LDD). We did not collect MRIs for our patients because such imaging is not routine for hip arthroplasty patients. We proposed a relatively simple way of assessing LDD on plain radiographs and its effect upon the standing and sitting changeswhichwe observed. Some patients in our study had no radiographic signs of spine arthrosis, but still had limited spine flexion. In the future, we may order MRIs for these patients to further evaluate the spine and consider why these patients have limited spine mobility. (RE: Esposito CI, Miller TT, Kim HJ, Barlow BT, Wright TM, Padgett DE, Jerabek SA, Mayman DJ. Does Degenerative Lumbar Spine Disease Influence Femoroacetabular Flexion in Patients Undergoing Total Hip Arthroplasty? Clin Orthop Relat Res. [Published online ahead of print March 28, 2016]. DOI: 10.1007/s11999-016-4787-2). The authors certify that they, or any member of their immediate families, have no funding or commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request. The opinions expressed are those of the writers, and do not reflect the opinion or policy of CORR or The Association of Bone and Joint Surgeons. C. I. Esposito PhD (&), T. T. Miller MD, H. J. Kim MD, B. T. Barlow MD, T. M. Wright PhD, D. E. Padgett MD, S. A. Jerabek MD, D. J. Mayman MD Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021, USA e-mail: espositoc@hss.edu Reply to the Letter to the Editor Published online: 6 June 2016 The Association of Bone and Joint Surgeons1 2016