PKHD1L1, a gene involved in the stereocilia coat, causes autosomal recessive nonsyndromic hearing loss.

Identification of genes associated with nonsyndromic hearing loss is a crucial endeavor given the substantial number of individuals who remain without a diagnosis after even the most advanced genetic testing. PKHD1L1 was established as necessary for the formation of the cochlear hair-cell stereociliary coat and causes hearing loss in mice and zebrafish when mutated. We sought to determine if biallelic variants in PKHD1L1 also cause hearing loss in humans. Exome sequencing was performed on DNA of four families segregating autosomal recessive nonsyndromic sensorineural hearing loss. Compound heterozygous p.[(Gly129Ser)];p.[(Gly1314Val)] and p.[(Gly605Arg)];p[(Leu2818TyrfsTer5)], homozygous missense p.(His2479Gln) and nonsense p.(Arg3381Ter) variants were identified in PKHD1L1 that were predicted to be damaging using in silico pathogenicity prediction methods. In vitro functional analysis of two missense variants was performed using purified recombinant PKHD1L1 protein fragments. We then evaluated protein thermodynamic stability with and without the missense variants found in one of the families and performed a minigene splicing assay for another variant. In silico molecular modeling using AlphaFold2 and protein sequence alignment analysis were carried out to further explore potential variant effects on structure. In vitro functional assessment indicated that both engineered PKHD1L1 p.(Gly129Ser) and p.(Gly1314Val) mutant constructs significantly reduced the folding and structural stabilities of the expressed protein fragments, providing further evidence to support pathogenicity of these variants. Minigene assay of the c.1813G>A p.(Gly605Arg) variant, located at the boundary of exon 17, revealed exon skipping leading to an in-frame deletion of 48 amino acids. In silico molecular modeling exposed key structural features that might suggest PKHD1L1 protein destabilization. Multiple lines of evidence collectively associate PKHD1L1 with nonsyndromic mild-moderate to severe sensorineural hearing loss. PKHD1L1 testing in individuals with mild-moderate hearing loss may identify further affected families.

PKHD1L1, A Gene Involved in the Stereocilia Coat, Causes Autosomal Recessive Nonsyndromic Hearing Loss.

Identification of genes associated with nonsyndromic hearing loss is a crucial endeavor given the substantial number of individuals who remain without a diagnosis after even the most advanced genetic testing. PKHD1L1 was established as necessary for the formation of the cochlear hair-cell stereociliary coat and causes hearing loss in mice and zebrafish when mutated. We sought to determine if biallelic variants in PKHD1L1 also cause hearing loss in humans. Exome sequencing was performed on DNA of four families segregating autosomal recessive nonsyndromic sensorineural hearing loss. Compound heterozygous p.[(Gly129Ser)];p.[(Gly1314Val)] and p.[(Gly605Arg)];p[(Leu2818TyrfsTer5)], homozygous missense p.(His2479Gln) and nonsense p.(Arg3381Ter) variants were identified in PKHD1L1 that were predicted to be damaging using in silico pathogenicity prediction methods. In vitro functional analysis of two missense variants was performed using purified recombinant PKHD1L1 protein fragments. We then evaluated protein thermodynamic stability with and without the missense variants found in one of the families and performed a minigene splicing assay for another variant. In silico molecular modelling using AlphaFold2 and protein sequence alignment analysis were carried out to further explore potential variant effects on structure. In vitro functional assessment indicated that both engineered PKHD1L1 p.(Gly129Ser) and p.(Gly1314Val) mutant constructs significantly reduced the folding and structural stabilities of the expressed protein fragments, providing further evidence to support pathogenicity of these variants. Minigene assay of the c.1813G>A p.(Gly605Arg) variant, located at the boundary of exon 17, revealed exon skipping leading to an in-frame deletion of 48 amino acids. In silico molecular modelling exposed key structural features that might suggest PKHD1L1 protein destabilization. Multiple lines of evidence collectively associate PKHD1L1 with nonsyndromic mild-moderate to severe sensorineural hearing loss. PKHD1L1 testing in individuals with mild-moderate hearing loss may identify further affected families.

Randomized Controlled Trials for Geriatric Hip Fracture Are Rare and Underpowered: A Systematic Review and a Call for Greater Collaboration.

BACKGROUND: Geriatric hip fracture is a common condition, and there are many open questions regarding patient management. Among the various types of medical evidence, the prospective randomized controlled trial (RCT) is considered the best. Our primary hypothesis was that small sample size would be seen frequently among RCTs involving geriatric patients with hip fracture. A related hypothesis was that studies from the United States would have particularly large deficits in sample size. Therefore, we asked the following research questions: (1) What is the mean sample size of RCTs involving geriatric patients with hip fracture? (2) How do sample sizes for studies from the U.S. differ from those performed elsewhere? METHODS: Following the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines, a systematic review of hip fracture RCTs was conducted. The Embase and MEDLINE databases were searched. Additional data included the country of origin, the power of the study, and whether sample size calculations were performed. One hundred and forty-seven RCTs were identified. RESULTS: The mean sample size of the 147 RCTs was 134.9. The mean sample size for the 7 American trials was 110.3, and the mean sample size for all trials conducted outside of the United States was 136.1. A sample size that was sufficient to ensure 80% power was used in only 31.3% of the RCTs. CONCLUSIONS: RCTs for hip fracture are small and underpowered. Moreover, <5% of the RCT studies have been conducted in the U.S., and they were smaller than those conducted elsewhere. The shortage of American trials may be a feature of the dispersion of geriatric hip fracture care across many hospitals in the United States. If so, better clinical research might require more centralized care (e.g., in specialized geriatric hip fracture centers) or greater collaboration among the many hospitals that provide care.

Do Infield Softball Masks Effectively Reduce Facial Fracture Risk?

Infield softball masks are intended to reduce facial fracture risk, but are rarely worn. The objective of this study was to evaluate the effectiveness of infield masks' ability to attenuate facial fracture risk over a range of designs and materials. To simulate batted ball impacts, a customized pitching machine was used to propel softballs at 24.6 ± 0.51 m/s. The balls impacted locations centered over the maxilla and zygoma bones of a FOCUS headform. The FOCUS headform was attached to a 50th percentile Hybrid III neck and secured to a slider table. Facial fracture risk of each facial bone was compared between masks and impact locations using peak resultant forces. Analysis of these data showed that the mask material and the distance between the mask and the impacted facial bone were key factors in determining a mask's performance. The effectiveness of masks varied. It was found that a metal mask with a separation distance ≥ 35 mm away from the maxilla and ≥ 25 mm away from the zygoma best reduced facial fracture risk for these test configurations. Plastic masks performed worse because they excessively deformed allowing ball contact with the face. This study assesses various mask designs for their ability to reduce facial fracture and suggests design recommendations based on the impact configurations tested.

Prospective Study of Central versus Peripheral Obesity in Total Knee Arthroplasty.

PURPOSE: Body mass index (BMI) is often used to predict surgical difficulty in patients receiving total knee arthroplasty (TKA); however, BMI neglects variation in the central versus peripheral distribution of adipose tissue. We sought to examine whether anthropometric factors, rather than BMI alone, may serve as a more effective indication of surgical difficulty in TKA. MATERIALS AND METHODS: We prospectively enrolled 67 patients undergoing primary TKA. Correlation coefficients were used to evaluate the associations of tourniquet time, a surrogate of surgical difficulty, with BMI, pre- and intraoperative anthropometric measurements, and radiographic knee alignment. Similarly, Knee Injury and Osteoarthritis Outcome Score (KOOS) was compared to BMI. RESULTS: Tourniquet time was significantly associated with preoperative inferior knee circumference (p=0.025) and ankle circumference (p=0.003) as well as the intraoperative depth of incision at the quadriceps (p=0.014). BMI was not significantly associated with tourniquet time or any of the radiographic parameters or KOOS scores. CONCLUSIONS: Inferior knee circumference, ankle circumference, and depth of incision at the quadriceps (measures of peripheral obesity) are likely better predictors of surgical difficulty than BMI. Further study of alternative surgical indicators should investigate patients that may be deterred from TKA for high BMI, despite relatively low peripheral obesity.

Temporal Healing of Achilles Tendons After Injury in Rodents Depends on Surgical Treatment and Activity.

INTRODUCTION: Achilles tendon ruptures affect 15 of 100,000 women and 55 of 100,000 men each year. Controversy continues to exist regarding optimal treatment and rehabilitation protocols. The objective of this study was to investigate the temporal effects of surgical repair and immobilization or activity on Achilles tendon healing and limb function after complete transection in rodents. METHODS: Injured tendons were repaired (n = 64) or left nonrepaired (n = 64). The animals in both cohorts were further randomized into groups immobilized in plantar flexion for 1, 3, or 6 weeks that later resumed cage and treadmill activity for 5, 3, or 0 weeks, respectively (n = 36 for each regimen), which were euthanized at 6 weeks after injury, or into groups immobilized for 1 week and then euthanized (n = 20). RESULTS: At 6 weeks after injury, the groups that had 1 week of immobilization and 5 weeks of activity had increased range of motion and decreased ankle joint toe stiffness compared with the groups that had 3 weeks of immobilization and 3 weeks of activity. The groups with 6 weeks of immobilization and no activity period had decreased tendon cross-sectional area but increased tendon echogenicity and collagen alignment. Surgical treatment dramatically decreased fatigue cycles to failure in repaired tendons from groups with 1 week of immobilization and 5 weeks of activity. Normalized comparisons between 1-week and 6-week postinjury data demonstrated that changes in tendon healing properties (area, alignment, and echogenicity) were maximized by 1 week of immobilization and 5 weeks of activity, compared with 6 weeks of immobilization and no activity period. DISCUSSION: This study builds on an earlier study of Achilles tendon fatigue mechanics and functional outcomes during early healing by examining the temporal effects of different immobilization and/or activity regimens after initial postinjury immobilization. CONCLUSION: This study demonstrates how the temporal postinjury healing response of rodent Achilles tendons depends on both surgical treatment and the timing of immobilization/activity timing. The different pattern of healing and qualities of repaired and nonrepaired tendons suggest that two very different healing processes may occur, depending on the chosen immobilization/activity regimen.

Pulsed electromagnetic field therapy improves tendon-to-bone healing in a rat rotator cuff repair model.

Rotator cuff tears are common musculoskeletal injuries often requiring surgical intervention with high failure rates. Currently, pulsed electromagnetic fields (PEMFs) are used for treatment of long-bone fracture and lumbar and cervical spine fusion surgery. Clinical studies examining the effects of PEMF on soft tissue healing show promising results. Therefore, we investigated the role of PEMF on rotator cuff healing using a rat rotator cuff repair model. We hypothesized that PEMF exposure following rotator cuff repair would improve tendon mechanical properties, tissue morphology, and alter in vivo joint function. Seventy adult male Sprague-Dawley rats were assigned to three groups: bilateral repair with PEMF (n = 30), bilateral repair followed by cage activity (n = 30), and uninjured control with cage activity (n = 10). Rats in the surgical groups were sacrificed at 4, 8, and 16 weeks. Control group was sacrificed at 8 weeks. Passive joint mechanics and gait analysis were assessed over time. Biomechanical analysis and µCT was performed on left shoulders; histological analysis on right shoulders. Results indicate no differences in passive joint mechanics and ambulation. At 4 weeks the PEMF group had decreased cross-sectional area and increased modulus and maximum stress. At 8 weeks the PEMF group had increased modulus and more rounded cells in the midsubstance. At 16 weeks the PEMF group had improved bone quality. Therefore, results indicate that PEMF improves early tendon healing and does not alter joint function in a rat rotator cuff repair model. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:902-909, 2017.

Autologous tendon-derived cell-seeded nanofibrous scaffolds improve rotator cuff repair in an age-dependent fashion.

Rotator cuff tendon tears are one of the most common shoulder pathologies, especially in the aging population. Due to a poor healing response and degenerative changes associated with aging, rotator cuff repair failure remains common. Although cell-based therapies to augment rotator cuff repair appear promising, it is unknown whether the success of such a therapy is age-dependent. We hypothesized that autologous cell therapy would improve tendon-to-bone healing across age groups, with autologous juvenile cells realizing the greatest benefit. In this study, juvenile, adult, and aged rats underwent bilateral supraspinatus tendon repair with augmentation of one shoulder with autologous tendon-derived cell-seeded polycaprolactone scaffolds. At 8 weeks, shoulders treated with cells in both juvenile and aged animals exhibited increased cellularity, increased collagen organization, and improved mechanical properties. No changes between treated and control limbs were seen in adult rats. These findings suggest that cell delivery during supraspinatus repair initiates earlier matrix remodeling in juvenile and aged animals. This may be due to the relative "equilibrium" of adult tendon tissue with regards to catabolic and anabolic processes, contrasted with actively growing juvenile tendons and degenerative aged tendons. This study demonstrates the potential for autologous cell-seeded scaffolds to improve repairs in both the juvenile and aged population. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1250-1257, 2017.