The Effect of Thumb Metacarpophalangeal Hyperextension on Thumb Axial Load and Lateral Pinch Force in a Cadaver Model of Thumb Trapeziectomy and Flexor Carpi Radialis Suspensionplasty.

PURPOSE: The purpose of our study was to investigate, in a cadaver model, the effect of increasing thumb metacarpophalangeal (MCP) joint hyperextension on thumb axial load and key pinch force after thumb trapeziectomy and flexor carpi radialis suspensionplasty. We developed a cadaveric model to test whether thumb MCP joint hyperextension after trapeziectomy would have a negative effect on key pinch force and increase loads across a reconstructed thumb carpometacarpal (CMC) joint. METHODS: We created a cadaveric biomechanical model that varied thumb MCP joint hyperextension while measuring thumb CMC axial and key pinch force under standardized loads. Direct observations were made of how key pinch and axial thumb CMC force change with increasing thumb MCP joint hyperextension. We measured the thumb key pinch force and axial thumb CMC joint load with the thumb MCP joint in 0°, 10°, 20°, 30°, 40°, 50°, and 60° of hyperextension. RESULTS: There was a 0.88 N (2.4%) increase in axial force across the thumb CMC per every 10° of increasing thumb MCP joint hyperextension. We found a 0.53 N (4.4%) reduction in key pinch force for every 10° of increasing thumb MCP joint hyperextension. Therefore, at 60° of thumb MCP joint hyperextension, the axial force across the thumb CMC increased by 5.3 N (14.6%) and the key pinch force was weakened by 3.2 N (26.6%). CONCLUSIONS: With progressive thumb MCP joint hyperextension after thumb CMC arthroplasty, we found a decrease in key pinch force and an increase in axial thumb CMC joint force. The decrease in key pinch force was larger than the relatively small increase in thumb CMC force. CLINICAL RELEVANCE: This study helps elucidate the biomechanics of the thumb CMC joint after resection arthroplasty with thumb MCP joint hyperextension and helps understand the interplay between these 2 conditions.

Total shoulder arthroplasty in patients with a B2 glenoid addressed with corrective reaming: mean 8-year follow-up.

BACKGROUND: The management of Walch B2 glenoid deformities in primary glenohumeral osteoarthritis is frequently debated. Previous literature has shown that the treatment of B2 glenoids with high-side reaming and anatomic total shoulder arthroplasty (aTSA) perform well in the short-term but is associated with an increased glenoid component failure rate in severe deformities. Therefore, many have explored alternative options, including augmented anatomic glenoid components and reverse shoulder arthroplasty. Our goal in this study is to provide mid-term radiographic and clinical outcomes after high-side reaming and aTSA for B2 glenoids. METHODS: Patients were followed both clinically and radiographically. Preoperative computed tomography scans were used for retrospective analysis of deformity. Both preoperative and postoperative visual analog scale pain, American Shoulder and Elbow Surgeons score, and Simple Shoulder Test scores were collected. Radiographs were analyzed preoperatively and postoperatively for humeral head decentering relative to the glenoid vault, immediate glenoid seating, and final glenoid peg radiolucency. RESULTS: Of the original cohort of 59 patients (6 now deceased) reported at a mean radiographic follow-up of 3.4 years, 34 shoulders in 33 patients with B2 glenoids (mean retroversion 18.9°, range 4°-32°) were available for follow-up at a mean of 8.6 years (range 5.5-11.2) after high-side glenoid reaming with aTSA. Three (5.1%) of the original 59 shoulder were revised. At final follow-up, 3 of 30 (10.0%) shoulders had radiographic glenoid component failure, but were unrevised. Glenoid component failure was associated with worse initial glenoid component seating (mean Lazarus score 1.2 vs. 2.0, P = .002). Glenoid failure was also associated with increased posterior humeral head subluxation at 2-4 year follow-up (mean 5.6% vs. 12.6%, P = .045) and at final follow-up (mean 7.0% vs. 21%, P = .002). There was no association between glenoid component failure and preoperative retroversion, inclination, or humeral head subluxation (all P > .05). Glenoid component failure was associated with worse American Shoulder and Elbow Surgeons (88 vs. 73) and visual analog scale pain (0.8 vs. 2.1) scores (both P = .03). CONCLUSIONS: At a mean of 8.6 years, 88% of shoulders available for follow-up had well-fixed glenoid components. Glenoid component failure was associated with poor initial glenoid component seating, with failed components having an average of 25% of the glenoid component not seated. Preoperative deformity such as glenoid retroversion, inclination, or humeral head subluxation did not predict glenoid component failure. This study supports that initial glenoid component seating and recurrence of posterior humeral head subluxation may be the most important factors for mid-term glenoid component survival in aTSA in patients with B2 glenoids.

Patient-Reported Outcomes After Total Hip Arthroplasty in a Low-Resource Country by a Visiting Surgical Team.

BACKGROUND: Total hip arthroplasty (THA) is a highly successful procedure but limited in many low-resource nations. In response, organizations globally have conducted service trips to provide arthroplasty care to underserved populations. Few outcomes data are currently available related to these trips. Our study aims to demonstrate the feasibility of tracking patient-reported outcomes and complications after THA in a low-resource setting and that outcomes are comparable to those in developed countries. METHODS: We completed an arthroplasty service trip to Brazil in 2017 where we performed 46 THAs on 38 patients. The mean patient age was 48.8 years. Forty-seven percent were female. Patient-reported outcome scores were collected preoperatively and postoperatively at 2, 6, and 12 weeks and 1 year. A multivariate regression analysis was performed to identify associations between patient factors and 12-week outcomes. RESULTS: The mean modified Harris Hip Score, Hip Disability and Osteoarthritis Outcome Score, Patient-Reported Outcome Measurement Information System Short Form (PROMIS-SF) Pain Interference, and PROMIS-SF Physical Function all improved significantly compared to baseline at 2, 6, and 12 weeks and 1 year postoperatively. At 1 year, only 29% of patients (11 of 38) were reachable by phone for follow-up.Multivariate regression analysis at 12 weeks found that females had more improvement in Hip Disability and Osteoarthritis Outcome Score for Joint Replacement scores (P = .003) and PROMIS-SF Pain Interference scores (P = .01) than males, and patients with rheumatoid arthritis had more improvement in PROMIS-SF Pain Interference scores (P = .008) compared with all other diagnoses. CONCLUSION: Patients in low-resource countries benefitted significantly from THA performed by a visiting surgical team. However, following up patients is difficult in low-resource countries once they leave the hospital.

Imbalance in Axial-plane Rotator Cuff Fatty Infiltration in Posteriorly Worn Glenoids in Primary Glenohumeral Osteoarthritis: An MRI-based Study.

BACKGROUND: Fatty infiltration of the rotator cuff evaluated with CT has been associated with asymmetric glenoid wear and humeral head subluxation in patients with glenohumeral arthritis. The relationship between rotator cuff pathologic findings and abnormal glenoid wear plays an important role in determining the optimal surgical management of advanced glenohumeral osteoarthritis. Compared with CT, MRI has increased sensitivity for identifying rotator cuff conditions; therefore, prior studies using CT may have underestimated the association between fatty infiltration of the rotator cuff and abnormal glenoid wear. QUESTIONS/PURPOSES: (1) Compared with Type A glenoids, which muscles in which Walch subtypes have a greater degree of fatty infiltration using Goutallier scores? (2) What glenoid type is associated with greater imbalance in fatty infiltration, as measured by comparing Goutallier scores between the posterior and anterior rotator cuff muscles? (3) What is the correlation between glenoid version and fatty infiltration of the rotator cuff muscles? (4) Comparing Type B2 and B3 glenoids with Type A glenoids, after accounting for age and sex, is there an increase in fatty infiltration of the infraspinatus muscle? METHODS: A total of 129 shoulders from 129 patients undergoing anatomic total shoulder arthroplasty to treat primary glenohumeral osteoarthritis were retrospectively reviewed. Patients had an average age of 66.4 ± 9.3 years and an average BMI of 30.6 ± 6.7 kg/m2, and 53% (69 of 129) were men. All patients underwent MRI within 12 months before total shoulder arthroplasty to assess glenoid morphology and rotator cuff pathologic findings. Three reviewers assessed the images, and glenoid morphology was assigned using the modified Walch classification system (Types A1, A2, B1, B2, B3, C, and D). Fatty infiltration of the rotator cuff was classified using Goutallier scores. The examiners demonstrated moderate-to-good reliability using these classification systems; the Walch classification system had interrater reliability kappa coefficients (κ) from 0.54 to 0.69 and intrarater reliability κ from 0.60 to 0.64. Goutallier scores using the simplified classification system had interrater reliability κ from 0.64 to 0.68 and intrarater reliability κ from 0.64 to 0.79. Thirty-six percent (46 of 129) of the shoulders had posterior wear patterns (18% [23] were Type B2 glenoids; 18% [23] were Type B3 glenoids). The average Goutallier scores for each rotator cuff muscle were determined, and the amount of fatty infiltration was compared between the various Walch subtypes using independent t-tests. Axial-plane imbalance in fatty infiltration of the rotator cuff was assessed by determining the difference in the average fatty infiltration of the posterior rotator cuff muscles (infraspinatus and teres minor) and anterior rotator cuff muscles (subscapularis) and comparing the differences among the Walch subtypes using independent t-tests. The association between glenoid version and fatty infiltration was assessed using Pearson correlations. Finally, a multivariate logistic regression model was used to assess fatty infiltration of the rotator cuff among the various Walch subtypes while accounting for patient age and sex. RESULTS: Compared with Type A1 glenoids, Type B2 and B3 glenoids had an increased amount of fatty infiltration of the infraspinatus (1.6 ± 0.7 versus 0.7 ± 0.4; mean difference 0.9 [95% CI 0.7-1.2]; p < 0.001 and 1.8 ± 0.4 versus 0.7 ± 0.4; mean difference 1.1 [95% CI 0.9-1.4]; p < 0.001, respectively) and teres minor (1.3 ± 0.7 versus 0.6 ± 0.5; mean difference 0.7 [95% CI 0.4-1.0]; p < 0.001 and 1.6 ± 0.6 versus 0.6 ± 0.5; mean difference 1.0 [95% CI 0.7-1.2]; p < 0.001, respectively). There was greater imbalance in fatty infiltration between the posterior and anterior rotator cuff muscles for Type B2 (0.5 ± 0.3) and B3 (0.6 ± 0.5) glenoids than for Type A1 (0.1 ± 0.3) and A2 (0.1 ± 0.6) glenoids (p < 0.001). Only the infraspinatus's fatty infiltration was strongly correlated with glenoid version (r = 0.64; p < 0.001), while fatty infiltration of the other muscles only correlated weakly or moderately. After accounting for age and sex, fatty infiltration in the infraspinatus was associated with Type B2 (OR 66.1 [95% CI 7.6-577.9]; p < 0.001) and Type B3 glenoids (OR 59.5 [95% CI 5.4-661.3]; p < 0.001) compared with Type A glenoids. CONCLUSION: Compared with concentric wear, posteriorly worn glenoids had an imbalance in axial-plane rotator cuff fatty infiltration and an increased amount of fatty infiltration of the infraspinatus and teres minor compared with the subscapularis. These imbalances may contribute to the higher rates of failure after anatomic total shoulder arthroplasty in patients with posterior wear compared with those with concentric wear. Future research should be directed toward investigating the temporal relationship of these findings, as well as understanding the clinical outcomes for patients undergoing anatomic total shoulder arthroplasty who have posteriorly worn glenoids with a high degree of fatty infiltration of the posterior rotator cuff musculature. CLINICAL RELEVANCE: Providers should consider the increased likelihood of higher-grade fatty infiltration of the posterior rotator cuff in the setting of posteriorly worn glenoids, particularly when treating patients without using MRI. These patients have higher rates of failure postoperatively and may benefit from closer monitoring and altered postoperative rehabilitation protocols that target the posterior rotator cuff.

Patient-Reported Outcomes Measurement Information System Correlates With Modified Harris Hip Score in Total Hip Arthroplasty.

The modified Harris Hip Score (mHHS) is a validated and disease-specific instrument commonly used to assess outcomes in total hip arthroplasty (THA). The Patient-Reported Outcomes Measurement Information System (PROMIS) is a validated, computer adaptive testing (CAT)-based global health assessment tool. The authors' goal was to examine the correlation between PROMIS Pain Interference and Physical Function CATs and the mHHS in patients undergoing primary THA. All THAs were performed by 1 of 2 fellowship-trained dedicated total joint surgeons at 1 academic institution. Patients completed PROMIS and mHHS assessments preoperatively and at 3, 6, 12, and 52 weeks postoperatively. Descriptive statistics and Pearson correlation values were determined. A total of 48 patients were prospectively enrolled in the study. Preoperatively, mean total PROMIS score (Pain Interference and Physical Function) was 74.2 and mHHS was 50.8. Preoperatively, mean total PROMIS score showed a moderate correlation (r=0.56; P<.0001) with total mHHS. Postoperatively, mean total PROMIS score at 3, 6, 12, and 52 weeks was 82.4, 93.4, 100, and 100, respectively (all P<.01 vs baseline), and mHHS was 68.2, 81.1, 85.9, and 88.6, respectively (all P<.01). At 3, 6, 12, and 52 weeks postoperatively, a strong and consistent correlation was observed between the total PROMIS score and mHHS (r=0.74, 0.74, 0.73, and 0.80, respectively; all P<.0001). The PROMIS Pain Interference and Physical Function CATs accurately assessed preoperative pain and dysfunction, as well as clinical improvement following THA. Combined PROMIS Pain Interference and Physical Function is comparable to the mHHS when assessing outcome following THA for osteoarthritis. [Orthopedics. 2021;44(1):e19-e25.].

Are single plane intraoperative and biplanar postoperative radiographic measurements of acetabular cup position the same?

PURPOSE: Supine positioning and the use of fluoroscopy during direct anterior approach total hip arthroplasty (DAA THA) have been reported to improve acetabular component positioning. This study aims to compare 2-dimensional intraoperative radiographic RadLink measurements of acetabular component position with 3-dimensional postoperative 3D SterEOS measurements. METHODS: Intraoperative fluoroscopy and RadLink (El Segundo, CA, USA) were used to measure acetabular cup position intraoperatively in 48 consecutive patients undergoing DAA THA. Cup position was measured on 6-week postoperative standing EOS images using 3D SterEOS software (EOS Imaging, SA, Paris, France) and compared to RadLink findings using Student's t-test. Safe-zone outliers were identified. We evaluated for measurement difference of > +/- 5°. RESULTS: RadLink acetabular cup abduction measurement (mean 43.0°) was not significantly different than 3D SterEOS in the anatomic plane (mean 42.6°, p = 0.50) or in the functional plane (mean 42.7°, p = 0.61). RadLink acetabular cup anteversion measurement (mean 17.9°) was significantly different than 3D SterEOS in both the anatomic plane (mean 20.6°, p = 0.022) and the functional plane (mean 21.2°, p = 0.002). RadLink identified 2 cups outside of the safe-zone. However, SterEOS identified 12 (anatomic plane) and 10 (functional plane) outside of the safe-zone. In the functional plane, 58% of anteversion and 92% of abduction RadLink measurements were within +/- 5° of 3D SterEOS. CONCLUSIONS: Intraoperative fluoroscopic RadLink acetabular anteversion measurements are significantly different than 3D SterEOS measurements, while abduction measurements are similar. Significantly more acetabular cups were noted to be outside of the safe-zone when evaluated with 3D SterEOS versus RadLink.

Anterior versus posterior approach total hip arthroplasty: patient-reported and functional outcomes in the early postoperative period.

PURPOSE: Direct anterior approach total hip arthroplasty (DA THA) has been reported to improve early outcomes compared to posterior approach THA up to 6 weeks postoperatively. Limited weekly outcomes data are available prior to 6 weeks. We evaluate outcomes including when patients first drive a car, leave home, and discontinue their assist device. METHODS: Patients undergoing THA for primary osteoarthritis were prospectively enrolled. Outcomes data were collected preoperatively and postoperatively at weekly intervals for 6 weeks. RESULTS: 111 patients (55 DA and 56 posterior approach) were enrolled. There was no significant difference (p > 0.05) in pre-surgical Patient-Reported Outcomes Measurement Information System (PROMIS) scores or modified Harris Hip Score (mHHS).Postoperatively, the DA THA group had decreased length of stay (p = 0.0002) and increased distance walked on postoperative day 1 and 2 (p = 0.011, p = 0.0004). The DA group had lower pain scores (p < 0.05) and required less day 1 and total narcotics (p = 0.029, p = 0.01). The DA cohort had improved PROMIS Physical Function scores and mHHS up to 5 weeks postoperatively. DA patients discontinued their assistive device 8 days earlier (p = 0.01), left home 3 days earlier (p = 0.001), and drove a car 5 days earlier (p = 0.01). CONCLUSIONS: Patients undergoing DA THA discontinued their assistive device, left their home, and drove a car sooner than posterior approach patients. We found improvement in physical function with DA, and it persisted up to 5 weeks postoperatively. Furthermore, DA patients had significantly shorter length of stay, improved mobilisation, decreased narcotic requirements and improved inpatient pain scores compared to posterior approach THA. Future randomised controlled study should be performed to minimise the biases inherent in this study methodology and confirm the results.

Prosthesis-Engaging Retrograde Femoral Nail with Locking Plate for the Treatment of a Vancouver B1 Periprosthetic Femur Fracture Nonunion: A Case Report.

CASE: Here, we describe a case of a Vancouver B1 periprosthetic femur fracture which initially went on to nonunion after open reduction and internal fixation. Union was ultimately achieved with a construct consisting of a prosthesis-engaging retrograde femoral nail and a locking compression plate. CONCLUSIONS: This case provides evidence that a construct consisting of a prosthesis-engaging retrograde femoral nail and a locking compression plate is an option for increasing fracture site stability in Vancouver B1 periprosthetic fractures and may be useful for patients with poor bone quality or a previously established nonunion.

Single-Use Custom Instrumentation in Total Knee Arthroplasty: Effect on In-Hospital Complications, Length of Stay, and Discharge Disposition.

Total knee arthroplasty (TKA) is a quality surgical intervention with rapidly increasing use. This growth has brought with it a host of new technologies, including custom instrumentation (CI). With the current emphasis on value-based health care, the clinical benefit of CI TKA must be evaluated. The goal of this study was to compare CI and conventional TKA regarding multiple quality metrics, in-hospital complications, length of stay, and discharge destination. The authors propensity score matched 231 conventional TKAs to 231 consecutive CI TKAs for age, sex, and body mass index. Preoperative risk factors analyzed were age, sex, body mass index, and preoperative hemoglobin. Perioperative factors included transfusion rate, hemoglobin drop, hemovac output, operative time, length of stay, discharge disposition, deep venous thrombosis and pulmonary embolism rates, and in-hospital vital sign data. There were no differences in preoperative demographics between groups. Postoperatively, there was no difference between conventional and CI TKA in operative time, transfusion rate, discharge hemoglobin, length of stay, discharge disposition, or in-hospital venous thromboembolism rates. In the conventional and CI groups, length of stay was 2.6 and 2.5 days (P=.43) and discharge disposition was 82% home and 83% home (P=.90), respectively. Although CI TKA is commonly implemented, in this analysis, compared with conventional TKA, it was not associated with any difference in length of stay, discharge disposition, operative time, transfusion rate, or in-hospital complications. [Orthopedics. 2019; 42(5):299-303.].

Valgus Osteotomy with Plate-and-Nail Fixation for the Treatment of Proximal Femoral Deformities Due to Fibrous Dysplasia: A Report of Two Cases.

CASE: We describe 2 cases of proximal femoral deformity due to fibrous dysplasia that were corrected with osteotomies and a novel combined construct with a blade plate and a retrograde intramedullary nail. CONCLUSION: A single-stage procedure using a combined construct with a blade plate and a retrograde intramedullary nail is a viable option for correcting and subsequently preventing proximal femoral deformities due to fibrous dysplasia.

Long leg splinting for pediatric femur fractures.

BACKGROUND: Pediatric femur fractures are frequently encountered injuries frequently treated with spica casting. Spica casting may, however, be expensive and burdensome to patients. A possible alternative is a long leg splint. METHODS: Patients aged 6 months to 5 years old who were treated for a femoral shaft fracture with a long leg splint extending above the waist were matched with a patient treated with a spica cast. RESULTS: At the time of healing, the alignment in the spica cast group was only significantly better than the alignment of the splint group with respect to coronal angulation.

The Effect of Smoking on Thirty-Day Postoperative Complications After Total Joint Arthroplasty: A Propensity Score-Matched Analysis.

BACKGROUND: Total joint arthroplasty (TJA) is a highly successful treatment, but is burdensome to the national healthcare budget. National quality initiatives seek to reduce costly complications. Smoking's role in perioperative complication after TJA is less well known. This study aims to identify smoking's independent contribution to the risk of short-term complication after TJA. METHODS: All patients undergoing primary TJA between 2011 and 2012 were selected from the American College of Surgeon's National Surgical Quality Improvement Program's database. Outcomes of interest included rates of readmission, reoperation, mortality, surgical complications, and medical complications. To eliminate confounders between smokers and nonsmokers, a propensity score was used to generate a 1:1 match between groups. RESULTS: A total of 1251 smokers undergoing TJA met inclusion criteria. Smokers in the combined total hip and knee arthroplasty cohort had higher 30-day readmission (4.8% vs 3.2%, P = .041), were more likely to have a surgical complication (odds ratio 1.84, 95% confidence interval 1.21-2.80), and had a higher rate of deep surgical site infection (SSI) (1.1% vs 0.2%, P = .007). Analysis of total hip arthroplasty only revealed that smokers had higher rates of deep SSI (1.3% vs 0.2%, P = .038) and higher readmission rate (4.3% vs 2.2%, P = .034). Analysis of total knee arthroplasty only revealed greater surgical complications (2.8% vs 1.2%, P = .048) and superficial SSI (1.8% vs 0.2%, P = .002) in smokers. CONCLUSION: Smoking in TJA is associated with higher rates of SSI, surgical complications, and readmission.

Multifaceted aseptic protocol decreases surgical site infections following hip arthroplasty.

INTRODUCTION: We investigate the effectiveness of a comprehensive aseptic protocol in reducing surgical site infection (SSI) after hip arthroplasty in a single medical centre with a high prevalence of methicillin-resistant Staphylococcus aureus (MRSA). METHODS: A prospectively collected database of all patients undergoing hip arthroplasty in a single centre between 2005 and 2011 was reviewed for SSI using Centers for Disease Control (CDC) criteria and AAOS guidelines. All patients were administered an aseptic protocol consisting of: preoperative 2% mupirocin nasal ointment and 0.4% chlorhexidine surgical-site wipes; modified instrument care; perioperative prophylactic vancomycin and cefazolin; and surgical-site skin preparation with chlorhexidine, alcohol and iodophor. We compare our protocol hip arthroplasty SSI rate to our institutional historical control and to contemporary literature. RESULTS: Among 774 patients, 69% were ASA>2, 45% had BMI≥30 and 10.3% had rheumatoid arthritis. We found an overall 0.39% infection rate; significantly lower than our institutional historical control (0.39% vs. 2.60%, p<0.001, OR 0.15, NNT 200) and significantly lower than 6 published reports (p<0.001-0.022, OR 0.16-0.22). Compared to these cohorts, significantly more of our patients were ASA>2, had BMI≥30 or had rheumatoid arthritis. Patients with 3 or more identifiable risk factors were at an increased risk of SSI compared to those with 2 or fewer risk factors. CONCLUSIONS: Our aseptic protocol decreases SSI in a high-risk population undergoing hip arthroplasty in a medical centre and community with a high prevalence of MRSA.

Qigong Exercises for the Management of Type 2 Diabetes Mellitus.

Background: The purpose of this article is to clarify and define medical qigong and to identify an appropriate study design and methodology for a large-scale study looking at the effects of qigong in patients with type 2 diabetes mellitus (T2DM), specifically subject enrollment criteria, selection of the control group and study duration. Methods: A comprehensive literature review of English databases was used to locate articles from 1980-May 2017 involving qigong and T2DM. Control groups, subject criteria and the results of major diabetic markers were reviewed and compared within each study. Definitions of qigong and its differentiation from physical exercise were also considered. Results: After a thorough review, it was found that qigong shows positive effects on T2DM; however, there were inconsistencies in control groups, research subjects and diabetic markers analyzed. It was also discovered that there is a large variation in styles and definitions of qigong. Conclusions: Qigong exercise has shown promising results in clinical experience and in randomized, controlled pilot studies for affecting aspects of T2DM including blood glucose, triglycerides, total cholesterol, weight, BMI and insulin resistance. Due to the inconsistencies in study design and methods and the lack of large-scale studies, further well-designed randomized control trials (RCT) are needed to evaluate the 'vital energy' or qi aspect of internal medical qigong in people who have been diagnosed with T2DM.

Can high-friction intraannular material increase screw pullout strength in osteoporotic bone?

BACKGROUND: Osteoporotic bone brings unique challenges to orthopaedic surgery, including a higher likelihood of problematic screw stripping in cancellous bone. Currently, there are limited options to satisfactorily repair stripped screws. Additionally, nonstripped screws hold with less purchase in osteoporotic bone. QUESTIONS/PURPOSES: This study attempts to answer the following questions: (1) Does high-friction intraannular (HFIA) augmentation increase pullout strength in osteoporotic and in severely osteoporotic bone; and (2) can HFIA repair stripped bone thread in osteoporotic and severely osteoporotic bone? METHODS: We measured screw pullout strength using a synthetic bone model in three groups: (1) predrilled nonstripped control holes as controls; (2) predrilled nonstripped augmented with HFIA; and (3) predrilled stripped holes repaired with HFIA. We tested this in osteoporotic and severely osteoporotic synthetic bone for a total of six test groups. We measured screw pullout force using an electromechanical tensile-testing machine comparing pullout force between the test groups and controls. RESULTS: HFIA augmentation did not increase pullout force compared with the control group in the osteoporotic bone model (489 ± 175 versus 607 ± 76, respectively; effect size = 0.94 [95% confidence interval {CI}, -1.75 to 0.08], p = 0.06). However, in severely osteoporotic cancellous bone that was augmented, the HFIA material generated more pullout force than the control (51 ± 18 versus 35 ± 16, respectively; effect size = 0.94 [95% CI, -0.02 to 1.82], p = 0.05). In stripped holes, HFIA partially restored pullout strength but remained weaker than controls in both osteoporotic and severely osteoporotic bone models (osteoporotic: 320 ± 59 versus 607 ± 76, respectively; effect size = -4.28 [95% CI, -5.57 to -2.51], p < 0.001; severely osteoporotic: 21 ± 8 versus 35 ± 16, respectively; effect size = -1.13 [95% CI, -2.0 to 0.12], p = 0.027). CONCLUSIONS: HFIA effectively augmented severely osteoporotic bone for screw purchase, but this effect was not seen for osteoporotic bone. In a model simulating both osteoporotic and severely osteoporotic bone, we found that HFIA can be used to repair stripped screw holes, but the resulting construct remains weaker than nonstripped controls. CLINICAL RELEVANCE: The HFIA material looks promising as a potential solution to stripped screws in osteoporotic bone. However, this material has yet to be tested in human bone. Furthermore, the fine mesh material could be damaged by autoclaving and could break off in vivo causing unknown tissue reactions. We recommend additional testing in a living animal model to better understand how living bone will react to the HFIA material.