Utilization of a Clinic-Based Hand Surgery Procedure Room in the US Military Health System: A Performance Improvement Analysis of Resource Savings and Patient Satisfaction.

PURPOSE: Recent studies examining the implementation of clinic-based procedure rooms (PRs) for wide-awake hand surgery have reported cost reduction, decreased burden on hospital systems, and improved patient satisfaction. This study evaluates other resource savings, primarily time spent by patients in the hospital. METHODS: Thirty-two patients were enrolled in a PR or the operating room group for prospective evaluation. Time spent in the hospital on the day of surgery, several preprocedure appointments, complications, and cost comparisons were evaluated between the two groups. Patient-reported outcomes were also evaluated with postoperative surveys assessing anxiety, pain, and satisfaction. RESULTS: Significant time savings were noted between the groups. The median time spent in the hospital on the day of surgery for the patients in the operating room group was 256 minutes versus 90 minutes for the PR group, a time savings of approximately 3 hours. Eight additional preoperative clinic visits for operating room patients were generated compared with no additional preoperative visits for PR patients. Cost savings for surgeries performed in the clinic-based procedure amounted to $232,411. No postoperative complications were observed in the clinic setting. CONCLUSIONS: Continued utilization of the clinical PR for select hand surgery procedures will reduce the cost and time burdens for procedures while maintaining satisfaction and safety. CLINICAL RELEVANCE: A clinic-based PR for performing minor hand surgeries saves the patient time and ostensibly allows the operating room to be used for more complex surgeries that are not easily amenable to a wide-awake in-clinic procedure.

Bilateral Chronic Quadriceps Tendon Ruptures Treated with Hamstring Autograft Reconstruction: A Case Report.

CASE: A 30-year-old semiprofessional football player presented with chronic bilateral quadriceps tendon ruptures. Both quadriceps tendon ruptures were unsuitable for isolated primary repair because of tendon retraction and immobility. A novel reconstruction technique using semitendinosus and gracilis tendon autografts was performed to restore both lower extremities' disrupted extensor mechanisms. At the final follow-up, the patient regained excellent motion of both knees and returned to high-intensity activity. CONCLUSION: Chronic quadriceps tendon ruptures present challenges related to tendon quality and mobilization. Reconstruction with hamstring autograft using a Pulvertaft weave through the retracted quadriceps tendon in a high-demand athletic patient represents a novel approach for treating this injury.

A Longitudinal Perspective on Conversion to Amputation for Combat-Related Extremity Injuries Treated With Flap-Based Limb Salvage.

OBJECTIVES: To define the rate and primary drivers behind early and late amputation after flap-based limb salvage in the setting of combat extremity trauma. DESIGN: Retrospective review. SETTING: Level II trauma center. PATIENTS: 307 (303 men, 4 women) patients who underwent flap-based limb salvage treatment between 2003 and 2014. INTERVENTION: We reviewed patient medical records, radiographs, and clinical photographs. MAIN OUTCOME MEASUREMENTS: Early and late amputation rates, time to amputation, reason for amputation. RESULTS: 307 patients accounted for 323 limbs that underwent flap-based limb salvage treatment (187 lower extremities, 136 upper extremities). A total of 58 extremities (18%) initially treated with flap-based limb salvage ultimately underwent amputation at a median of 480 days (IQR, 285-715 days) from injury. Periarticular fractures and lower extremity injuries were risk factors for early and late amputation. Other independent risk factors for early amputation were flap complications and vascular injuries, whereas risk factors for late amputation were fractures that went on to nonunion. CONCLUSIONS: This study highlights that a subset of patients ultimately require major limb amputation despite having achieved what is initially considered "successful" limb salvage. Flap-related complications, vascular injury, and lower extremity site of injury were associated with early amputation after successful expeditionary efforts at limb preservation. Conversion to late amputation was associated with lower extremity periarticular fractures and fracture nonunion. Chronic pain and persistent limb dysfunction were the most common reasons for late amputation. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Beyond Limb Salvage: Limb Restoration Efforts Following Remote Combat-Related Extremity Injuries Optimize Outcomes and Support Sustained Surgical Readiness.

INTRODUCTION: As the combat operational tempo of the military conflicts in Iraq and Afghanistan has declined over the last decade, there has been a decrease in the number of patients requiring acute limb salvage. In their place, a growing population of patients with persistent functional deficits, pain, and inadequate soft tissue coverage stemming from prior limb salvage strategies have returned to our institution seeking revision surgery. Herein, we examine our institution's evolving surgical approach to extremity reconstruction from 2011 through 2019, culminating in the development of our limb restoration concept. We also discuss the impact of this orthoplastic approach on the acute management of complex extremity trauma and its role in providing sustained surgical readiness during interwar years. MATERIALS AND METHODS: We retrospectively reviewed all limb reconstructive procedures performed at our tertiary care military treatment facility between September 1, 2011 to December 31, 2019 to characterize the trends in extremity reconstruction procedures performed at our institution. Cases were identified as limb restoration procedures if they involved secondary/revision reconstructive procedures designed to optimize function, treat pain, or improve the durability of the injured extremity following initial reconstruction efforts. RESULTS: Nearly 500 limb restoration procedures were performed during the study period. These procedures steadily increased since 2011, reaching a maximum of 120 in 2018. Orthoplastic procedures such as osseointegration, targeted muscle reinnervation, regenerative peripheral nerve interface, agonist-antagonist myoneural interface, and soft tissue resurfacing flap reconstruction accounted for the rise in secondary/revision reconstruction performed during this time period. CONCLUSION: Limb restoration is a collaborative orthoplastic approach that utilizes state-of-the-art surgical techniques for treating complex extremity trauma. Although limb restoration originally developed in response to managing the long-term sequelae of combat extremity trauma, the concept can be adapted to the acute management setting. Moreover, limb restoration provides military surgeons with a means for maintaining critical war-time surgical skills during the current low casualty rate era. Level of Evidence: V, therapeutic.

A Modified Scapular-Parascapular Flap Design for Optimal Coverage of the Residual Limb.

BACKGROUND: Large soft tissue defects associated with major limb amputation pose a challenge to the reconstructive surgeon due to the 3-dimensional contour of the residual limb and the need to withstand the unnatural shear forces imparted by prosthetic sockets. Fasciocutaneous flaps based on the circumflex scapular system have proven useful for residual limb coverage due to the durability of the tissue provided, the absence of functional morbidity, and the ease of reelevation. A modified, bilobed flap design that incorporates large Burrow triangles into each limb serves to leverage the perforasome anatomy of the posterior trunk to provide maximal 3-dimensional coverage and favorable flap geometry while also facilitating donor site closure. METHODS: A retrospective medical record review was performed for all patients who underwent reconstruction of a residual limb after major amputation using the modified, bilobed scapular-parascapular free flap design at Walter Reed National Military Medical Center between 2018 and 2021. A computer-based application was used to calculate flap area and dimensions based on photographs of preoperative and intraoperative markings. RESULTS: Six patients with varying amputation levels (2 transtibial, 1 transfemoral, 1 hip-disarticulation, 1 hemipelvectomy, 1 transradial) underwent soft tissue coverage using the modified flap design. Mean flap area was 318.4 cm 2 with 51.1 cm 2 attributable to the modified design. This represents a 16% increase over a conventional bilobed design. There were no partial or complete flap failures. CONCLUSIONS: The modified scapular-parascapular flap design enables harvest of a larger and more versatile fasciocutaneous flap with geometry that is well suited for coverage of the residual limb.

The Incidence, Risk Factors, and Complications Associated With Surgical Delay in Multilevel Fusion for Adult Spinal Deformity.

STUDY DESIGN: Retrospective database review. OBJECTIVES: The incidence and risk factors for surgical delay of multilevel spine fusion for adult spinal deformity (ASD), and the complications corresponding therewith, remain unknown. The objectives of this study are to assess the incidence and risk factors for unexpected delay of elective multilevel spinal fusions on the date of surgery as well as the postoperative complications associated with these delays. METHODS: We conducted a retrospective review of the ACS-NSQIP database on patients undergoing elective spinal instrumentation of greater than 7 levels for ASD between the years 2005 and 2015. Preoperative risk factors for delay and postoperative complications were compared between the cohorts of patients with and without surgical delays. RESULTS: Multivariate analysis of 1570 (15.6%) patients identified advanced age, male sex, American Society of Anesthesiologists (ASA) Class 4, and history of smoking as independent risk factors for delay. Patients experiencing surgical delay demonstrated longer operative times, increased intraoperative bleeding, longer hospitalizations, and significantly higher rates of postoperative complications. Patients experiencing delay demonstrated an almost 7-fold increase in mortality rate (3.4% vs 0.5%, P < .001). CONCLUSIONS: Delays in elective surgical care for spinal deformity are negatively related to patient outcomes. Advanced age, male sex, increased ASA class, and a history of smoking cigarettes place patients at risk for surgical delay of multilevel spinal fusion. Patients experiencing surgical delay are at higher risk for postoperative complications, including a 7-fold increase in mortality. These findings suggest that ASD surgery should be postponed in patients experiencing a delay, until modifiable risk factors can be medically optimized, and perhaps postponed indefinitely in those with nonmodifiable risk factors.

Institutional Experience and Orthoplastic Collaboration Associated with Improved Flap-based Limb Salvage Outcomes.

BACKGROUND: Flap-based limb salvage surgery balances the morbidity and complexity of soft tissue transfer against the potential benefit of preserving a functional limb when faced with a traumatized extremity with composite tissue injury. These composite tissue injuries are well suited for multidisciplinary management between orthopaedic and plastic surgeons. Thus, it makes intuitive sense that a collaborative, orthoplastic approach to flap-based limb salvage surgery can result in improved outcomes with decreased risk of flap failure and other complications, raising the question of whether this orthoplastic team approach should be the new standard of care in limb salvage surgery. QUESTIONS/PURPOSES: (1) Is there an association between increased annual institutional volume and perioperative complications to include free and local flap failure (substantial flap viability loss necessitating return to the operating room for debridement of a major portion or all of the flap or amputation)? (2) Is an integrated orthoplastic collaborative approach to managing combat-related traumatic injuries of the extremities individually associated with a decreased risk of flap failure and overall flap-related complications? (3) What other factors, such as location of injury, injury severity score, and initial inpatient length of stay, were associated with flap necrosis and flap-related complications? METHODS: We performed a retrospective review of the electronic medical records of all patients who underwent flap-based limb salvage for combat-related extremity trauma in the United States Military Health System's National Capital Region between January 1, 2003 and December 31, 2012. In total, 307 patients underwent 330 flap procedures. Of the 330 flaps, 59% (195) were local or pedicled flaps and 41% (135) were free flaps. Patients were primarily male (99% [303]), with a median (interquartile range) age of 24 years old (IQR 21 to 29), and 87% (267 of 307) of injuries were sustained from a blast mechanism. We collected data on patient demographics, annual case volume involving flap coverage of extremities, mechanism of injury, flap characteristics, perioperative complications, flap failure, flap revision, isolated orthopaedic management versus an integrated orthoplastic approach, and other salvage procedures. For the purposes of this study, orthoplastic management refers to operative management of flap coverage with microvascular surgeons present for soft tissue transfer after initial debridement and fixation by orthopaedic surgery. The orthoplastic management was implemented on a case-by-case basis based on individual injury characteristics and the surgeon's discretion with no formal starting point. When implemented, the orthoplastic team consisted of an orthopaedic surgeon and microvascular-trained hand surgeons and/or plastic surgeons. In all, 77% (254 of 330) of flaps were performed using this model. We considered perioperative flap complications as any complication (such as infection, hematoma, dehiscence, congestion, or necrosis) resulting in return to the operating room for re-evaluation, correction, or partial debridement of the flap. We defined flap failure as a return to the operating room for debridement of a major portion of the flap or amputation secondary to complete or near-complete loss of flap viability. Of the flap procedures, 12% (40 of 330) were classified as a failure and 14% (46 of 330) experienced complications necessitating return to the operating room. Over the study period, free flaps were not more likely to fail than pedicled flaps (11% versus 13%; p = 0.52) or have complications necessitating additional procedures (14% versus 16%; p = 0.65). RESULTS: Our multiple linear regression model demonstrated that an increased number of free flaps performed in our institution annually in any given year was associated with a lower likelihood of failure per case (r = -0.17; p = 0.03) and lower likelihood of reoperation for each flap (r = -0.34; p < 0.001), after adjusting for injury severity and team type (orthoplastic or orthopaedic only). We observed a similar relationship for pedicled flaps, with increased annual case volume associated with a decreased risk of flap failure and reoperation per case after adjusting for injury severity and team type (r = -0.21; p = 0.003 and r = -0.22; p < 0.001, respectively). Employment of a collaborative orthoplastic team approach was associated with decreased flap failures (odds ratio 0.4 [95% confidence interval 0.2 to 0.9]; p = 0.02). Factors associated with flap failure included a lower extremity flap (OR 2.7 [95% CI 1.3 to 6.2]; p = 0.01) and use of muscle flaps (OR 2.3 [95% CI 1.1 to 5.3]; p = 0.02). CONCLUSION: Although prior reports of combat-related extremity trauma have described greater salvage success with the use of pedicled flaps, these reports are biased by institutional inexperience with free tissue transfer, the lack of a coordinated multiservice effort, and severity of injury bias (the most severe injuries often result in free tissue transfer). Our institutional experience, alongside a growing body of literature regarding complex extremity trauma in the civilian setting, suggest a benefit to free tissue coverage to treat complex extremity trauma with adequate practice volume and collaboration. We demonstrated that flap failure and flap-related complications are inversely associated with institutional experience regardless of flap type. Additionally, a collaborative orthoplastic approach was associated with decreased flap failures. However, these results must be interpreted with consideration for potential confounding between the increased case volume coinciding with more frequent collaboration between orthopaedic and plastic surgeons. Given these findings, consideration of an orthoplastic approach at high-volume institutions to address soft tissue coverage in complex extremity trauma may lead to decreased flap failure rates. LEVEL OF EVIDENCE: Level III, therapeutic study.

IDEO energy-storing orthosis: Effects on lower extremity function and preservation.

INTRODUCTION: The Intrepid Dynamic Exoskeletal Orthosis (IDEO) brace is a custom energy-storing orthosis design meant to improve gait, stability, and function after lower extremity injury or limb salvage. Early studies demonstrated the potential for the IDEO to improve functional performance, in conjunction with its paired return to run (RTR) rehabilitation program, compared to other brace types, and an impressively decreased rate of late amputation. The current study aimed to investigate these functional and revision outcomes from our institution to determine which patients may benefit most from IDEO bracing and what factors of the IDEO design and rehabilitation program are most important for improved outcomes after lower extremity trauma and/or loss of function. METHODS: We performed a retrospective review of all patients treated with a IDEO style brace at a single military lower extremity trauma referral center between May 2003 and November 2017. We reviewed the medical records for initial diagnosis, post-orthotic rehabilitation program, IDEO use characteristics, pain, change in desire for amputation, and whether patient underwent eventual amputation. RESULTS: We identified 213 patients with 222 lower extremities treated with IDEO brace. Of these, 76 limbs were treated for combat-related injuries. At one year follow-up, use status could not be determined for 37 extremities (16.7%). Of the 185 limbs with use data available, 116 (61.1%) continued regular brace use, and 37 (15.7%) reported intermittent use. Patients diagnosed with footdrop or weakness were more likely to continue use (OR 2.33, p=0.04), while patients with a previous fusion were less likely to continue use (OR 0.45, p=0.049). Undergoing any dedicated therapy increased chances of continued use (OR 3.37, p<0.001). At final follow-up, 16 patients (7.5%) underwent delayed lower extremity amputations following IDEO treatment. Overall, 27.2% of patients who initially desired amputation eventually underwent amputation despite IDEO brace use. Patients who underwent amputation reported higher pain levels (2 versus 5, p<0.001). DISCUSSION: In select patients, the IDEO may decrease the desire for delayed amputation and permit higher levels of activity; however, its efficacy appears tied to the rehabilitative regimen, pain levels, and initial diagnosis. These findings should guide post-surgical extremity bracing prescriptions and expectations.

The Incidence of Posterior and Combined AP Shoulder Instability Treatment with Surgical Stabilization Is Higher in an Active Military Population than in the General Population: Findings from the US Naval Academy.

BACKGROUND: Anterior instability has consistently been shown to be the most common type of glenohumeral instability. Recent studies have demonstrated a higher percentage of posterior and combined (anterior and posterior) instability than had previously been reported; however, this work has not been replicated recently in a particularly young military population, which may be representative of an especially athletic or high-demand group. QUESTION/PURPOSE: What proportion of arthroscopic shoulder stabilization procedures are performed to address isolated anterior instability, isolated posterior instability, and combined instability in a young, military population? METHODS: Between August 2009 and January 2020, two sports medicine fellowship-trained surgeons performed arthroscopic shoulder surgery on 543 patients at a single institution. During that time, the indication to be treated with arthroscopic stabilization surgery was symptomatic glenohumeral instability, as diagnosed by the operative surgeon, that restricted patients from carrying out their military duties. Of those, 82% (443 of 543) could be evaluated in this retrospective study, while 18% (100 of 543) were excluded due to either incomplete data or because the procedure performed was not to address instability. No patient underwent an open stabilization procedure during this period. Of the 443 patients investigated, the mean age was 22 ± 4 years, and 88% (392 of 443 patients) were men. Instability type was characterized as isolated anterior, isolated posterior, or combined (anterior and posterior) according to the physician's diagnosis as listed in the patient's clinical records and operative reports after the particular capsulolabral pathology was identified and addressed. RESULTS: Isolated anterior instability occurred in 47% of patients (210 of 443). Isolated posterior instability happened in 18% of patients (80 of 443), while combined anteroposterior instability occurred in 35% of patients (153 of 443). CONCLUSION: Shoulder instability is common in the military population. Although anterior instability occurred most frequently, these findings demonstrate higher proportions of posterior and combined instability than have been previously reported. Surgeons should have a heightened suspicion for posterior and combined anteroposterior labral pathology when performing arthroscopic stabilization procedures to ensure that these instability patterns are recognized and treated appropriately. The current investigation examines a unique cohort of young and active individuals who are at particularly high risk for instability and whose findings may represent a good surrogate for other active populations that a surgeon may encounter.Level of Evidence Level III; therapeutic study.

Functional Limb Restoration Through Amputation: Minimizing Pain and Optimizing Function With the Use of Advanced Amputation Techniques.

OBJECTIVE: To demonstrate the role of advanced orthoplastic techniques in harnessing the full potential of elective amputation as a functionally restorative procedure. SUMMARY OF BACKGROUND DATA: Once considered the unfortunate consequence of failed reconstructive efforts, recent outcomes studies have prompted a re-evaluation of the role of amputation in the management of complex extremity trauma. However, even as amputation is appropriately afforded greater consideration as part of the reconstructive algorithm, reconstructive techniques that are commonly utilized in pursuit of limb salvage are rarely applied to amputation. METHODS: The following case demonstrates the successful application of orthoplastic reconstructive techniques to achieve optimal pain and functional outcomes in a 41-year-old active duty soldier who underwent an elective transtibial amputation after prolonged, limb salvage. RESULTS: The patient presented with a large osteocutaneous proximal tibial defect secondary to trauma and subsequent osteomyelitis. The patient underwent a free scapular-parascapular fasciocutaneous flap to provide soft tissue coverage and facilitate the skeletal reconstruction necessary for either continued limb salvage or amputation. Due to tibial allodynia and severely limited ankle function, the patient subsequently elected for amputation in favor of continued limb salvage. Thus, a transtibial amputation was performed concurrently with a pedicled vascularized fibula to address the proximal tibial defect. A modified agonist-antagonist myoneural interface procedure was used to maximize post-amputation function, with creation of regenerative peripheral nerve interface constructs to prophylax against neurogenic pain. After the operation, the patient achieved improved function of the extremity with the use of a prosthesis and reported substantially improved pain while remaining on active duty in a warfighting military occupational specialty. CONCLUSIONS: By addressing all of the reconstructive components commonly considered in limb salvage, an orthoplastic approach to amputation surgery can minimize pain and maximize the rehabilitative potential of the amputee.

Synchronous Multifocal Necrotizing Fasciitis: A Case Report.

CASE: An immunocompetent 43-year-old man was diagnosed with necrotizing fasciitis of his forearm. Despite receiving appropriate treatment, his clinical condition continued to deteriorate. Further evaluation revealed subsequent proliferation of the infection to multiple noncontiguous areas of the body consistent with a rare condition known as synchronous multifocal necrotizing fasciitis. Prompt identification, followed by serial debridements of all affected areas, ultimately saved the patient's life. CONCLUSION: This unusual multifocal presentation of necrotizing fasciitis can produce diagnostic uncertainty and delay life-saving treatment. Early recognition, followed by prompt treatment, is paramount for reducing morbidity and mortality associated with this devastating infection.

The Inverted Free Functioning Gracilis Muscle Transfer For Restoration of Elbow Flexion Following Delayed Presentation or Failed Primary Nerve Reconstruction of Upper Trunk Injuries.

Free functional gracilis transfer is a well-established technique for restoring active elbow flexion in brachial plexus injuries following delayed presentation or failed nerve reconstruction procedures. In cases of delayed presentation or failed nerve reconstruction following upper trunk injuries, the lower trunk intraplexal median and ulnar nerves are spared, thereby making them available to reinnervate the transferred gracilis. Therefore, we have inverted the conventional free functional gracilis orientation so as to orient the flap's recipient nerve in closer proximity to donor median or ulnar nerve fascicles to enable a short, tension-free coaptation in the middle to distal arm. Herein is our descriptive surgical technique for performing an inverted free functional gracilis muscle transfer in order to restore elbow flexion in the setting of an upper trunk injury.

Managing Complex Peripheral Nerve Injuries Within the Military Health System: A Multidisciplinary Approach to Treatment, Education, and Research at Walter Reed National Military Medical Center.

INTRODUCTION: Peripheral nerve injuries are a leading cause of disability within the Military Health System (MHS) patient population. Many peripheral nerve injuries (PNIs) are amenable to therapeutic intervention but require a timely diagnosis and prompt referral to a specialty center capable of intervention, as functional outcomes are directly related to the duration between injury and intervention. Even when appropriately identified, PNI management in the MHS is often challenged by the lack of an established pathway for care coordination and a limited awareness of available diagnostic and therapeutic resources. To address these potential shortcomings, the Walter Reed National Military Medical Center Peripheral Nerve Program (WRNMMC PNP) in Bethesda, MD, has been established to provide comprehensive, multidisciplinary care to peripheral nerve-injured patients across the MHS. Additionally, the WRNMMC PNP provides graduate medical education training in PNI management for multiple residency and fellowship programs, and it facilitates critical peripheral nerve research to advance knowledge within the field. MATERIALS AND METHODS: A retrospective review of all patients evaluated by the WRNMMC PNP between December 2015 and April 2019 was conducted in order to identify pertinent patient demographic information, referral patterns, and PNI etiology data. RESULTS: The WRNMMC PNP evaluated 356 patients consisting of active duty, dependents, retirees, and Veterans Affairs patients during the designated study period. These patients were referred by providers from more than nine different specialties from 78 commands across eight countries. The majority of these patients (222 patients) were referred for traumatic PNI. The WRNMMC PNP has also evaluated and treated patients with PNIs stemming from congenital and compressive etiologies. One hundred and one patients referred during this period were treated with surgery, while the remainder were managed through nonoperative means. CONCLUSIONS: The WRNMMC PNP facilitates comprehensive, patient-centered care for PNI patients within the MHS. Moreover, the program helps to prepare the next generation of providers for evaluating and treating PNI patients through its involvement with graduate medical education training. It also conducts critical peripheral nerve research and lays the foundation for collaborations with other institutions involved with peripheral nerve research. In the years ahead, the WRNMMC PNP aims to expand its outreach and capabilities within the MHS through more expansive use of telemedicine consultation and the establishment of satellite peripheral nerve clinic sites.

Orthopaedic osseointegration: Implantology and future directions.

Osseointegration (OI) is the direct anchorage of a metal implant into bone, allowing for the connection of an external prosthesis to the skeleton. Osseointegration was first discovered in the 1960s based on the microscopic analysis of titanium implant placed into host bone. New bone was observed to attach directly to the metal surface. Following clinical investigations into dentistry applications, OI was adapted to treat extremity amputations. These bone anchored implants, which penetrate the skin and soft tissues, eliminate many of the challenges of conventional prosthetic sockets, such as poor fit and suspension, skin breakdown, and pain. Osseointegrated implants show promise to improve prosthesis use, pain, and function for amputees. The successful process of transcutaneous metal integration into host bone requires three synergistic systems: the host bone, the metal implant, and the skin-implant interface. All three systems must be optimized for successful incorporation and longevity of the implant. Osseointegration begins during surgical implantation of the metal components through a complex interplay of cellular mechanisms. While implants can vary in design-including the original screw, press fit implants, and compressive osseointegration-they face common challenges to successful integration and maintenance of fixation within the host bone. Overcoming these challenges requires the understanding of the complex interactions between each element of OI. This review outlines (a) the basic components of OI, (b) the science behind both the bone-implant and the skin-implant interfaces, (c) the current challenges of OI, and (d) future opportunities within the field.

Proximal Femur Hounsfield Units on CT Colonoscopy Correlate With Dual-energy X-ray Absorptiometry.

BACKGROUND: Quantifying bone mineral density (BMD) on CT using commercial software demonstrates good-to-excellent correlations with dual-energy x-ray absorptiometry (DEXA) results. However, previous techniques to measure Hounsfield units (HUs) within the proximal femur demonstrate less successful correlation with DEXA results. An effective method of measuring HUs of the proximal femur from CT colonoscopy might allow for opportunistic osteoporosis screening. QUESTIONS/PURPOSES: (1) Do proximal femur HU measurements from CT colonoscopy correlate with proximal femur DEXA results? (2) How effective is our single HU measurement technique in estimating the likelihood of overall low BMD? (3) Does the relationship between our comprehensive HU measurement and DEXA results change based on age, sex, or time between studies? METHODS: This retrospective study investigated the measurement of HU of the femur obtained on CT colonoscopy studies compared with DEXA results. Between 2010 and 2017, five centers performed 9085 CT colonoscopy studies; of those, 277 (3%) also had available DEXA results and were included in this study, whereas 8809 (97%) were excluded for inadequate CT imaging, lack of DEXA screening, or lack of proximal femur DEXA results. The median number of days between CT colonoscopy and DEXA scan was 595 days; no patient was excluded based on time between scans because bone remodeling is a long-term process and this allowed subgroup analysis based on time between scans. Two reviewers performed HU measurements at four points within the proximal femur on the CT colonoscopy imaging and intraclass correlation coefficients were used to evaluate interrater reliability. We used Pearson correlation coefficients to compare the comprehensive (average of eight measurements) and a single HU measurement with each DEXA result-proximal femur BMD, proximal femur T-score, femoral neck BMD, and femoral neck T-score-to identify the best measurement technique within this study. Based on their lowest DEXA T-score, we stratified patients to a diagnosis of osteoporosis, osteopenia, or normal BMD. We then calculated the area under the receiver operator characteristic curves (AUCs) to evaluate the classification ability of a single HU value to identify possible threshold(s) for detecting low BMD. For each subgroup analysis, we calculated Pearson correlation coefficients between DEXA and HUs and evaluated each subgroup's contribution to the overall predictive model using an interaction test in a linear regression model. RESULTS: The Pearson correlation coefficient between both the comprehensive and single HU measurements was highest compared with the proximal femur T-score at 0.75 (95% confidence interval [CI], 0.69-0.80) and 0.74 (95% CI, 0.68-0.79), respectively. Interobserver reliability, measured with intraclass correlation coefficients, for the comprehensive and single HU measurements was 0.97 (95% CI, 0.72-0.99) and 0.96 (95% CI, 0.89-0.98), respectively. Based on DEXA results, 20 patients were osteoporotic, 167 had osteopenia, and 90 patients had normal BMD. The mean comprehensive HU for patients with osteoporosis was 70 ± 30 HUs; for patients with osteopenia, it was 110 ± 36 HUs; and for patients with normal BMD, it was 158 ± 43 HUs (p < 0.001). The AUC of the single HU model was 0.82 (95% CI, 0.77-0.87). A threshold of 214 HUs is 100% sensitive and 59 HUs is 100% specific to identify low BMD; a threshold of 113 HUs provided 73% sensitivity and 76% specificity. When stratified by decade age groups, each decade age group demonstrated a positive correlation between the comprehensive HU and proximal femur T-score, ranging between 0.71 and 0.83 (95% CI, 0.59-0.91). Further subgroup analysis similarly demonstrated a positive correlation between the comprehensive HU and proximal femur T-score when stratified by > 6 months or < 6 months between CT and DEXA (0.75; 95% CI, 0.62-0.84) as well as when stratified by sex (0.70-0.76; 95% CI, 0.48-0.81). The linear regression model demonstrated that the overall positive correlation coefficient between HUs and the proximal femur T-score is not influenced by any subgroup. CONCLUSIONS: Our measurement technique provides a reproducible measurement of HUs within the proximal femur HUs on CT colonoscopy. Hounsfield units of the proximal femur based on this technique can predict low BMD. These CT scans are frequently performed before initial DEXA scans are done and therefore may lead to earlier recognition of low BMD. Future research is needed to validate these results in larger studies and to determine if these results can anticipate future fracture risk. LEVEL OF EVIDENCE: Level III, diagnostic study.

Low Revision Rates at 10 years for Metal on Metal Hip Implants in a Military Population.

INTRODUCTION: Prior to being largely abandoned due to unacceptably high failure rates and the adverse physiologic reactions to metal ions, metal-on-metal (MoM) total hip arthroplasty (THA) and hip resurfacing (HR) were in widespread use throughout the USA, and the potential benefit of decreased volumetric wear rates made it of particular interest to those who serve a young active population, such as military surgeons. The aim of our study was to determine the revision rate of metal on metal hip implants performed at our military institution and obtain current patient reported outcomes from this cohort. MATERIALS AND METHODS: We conducted a retrospective review of patients who underwent MoM total hip arthroplasty (THA) or hip resurfacing (HR) at our institution from 2006 to 2012. Revision status and component type were determined, and patients were contacted to obtain current HOOS JR scores. RESULTS: We identified 103 THAs in 88 patients and 38 HRs in 33 patients, with mean follow up of 10.2 years. Average age at time of surgery was 48 years, and 85% of the patients were male. The mean HOOS JR score in the THA and HR groups were 84.9 ± 17.6 and 75.8 ± 24.9, respectively (p = 0.38), and were not significantly lower in those who were revised. Two THA revisions occurred for metallosis and one for aseptic loosening of the femoral component. One HR revision occurred for breach of the anterior femoral neck, and one occurred for heterotopicossification. CONCLUSIONS: Revision rates of MoM THA and HR in this young, predominantly male population were 2.9% and 5.3%, respectively, and patients maintained generally good hip-specific outcomes.