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Open Access Publications from the University of California

Scholarly Works (80 results)

  • Thesis
  • Peer Reviewed
UC Berkeley Electronic Theses and Dissertations (2022)

Modern emergency response operations increasingly use remote ground-based sensors to provide real-time situational awareness for first responders. However, human users often must personally enter a dangerous situation to place the sensors. The seamless deployment of such sensors without human intervention allows for faster, wider distribution at minimal risk to human lives. This work presents a systematic approach to the design of impact-resistant tensegrity landers capable of autonomous high-altitude aerial deployment of critical sensor payloads in disaster scenarios.

Tensegrity structures are derived from the concept of “tensile integrity” and are composed of rigid rods suspended by elastic cables in a tension network. Their lightweight and flexible properties protect the sensor payload from landing impacts at high velocities. Design equations and simulation models are first used to inform the hardware design of the tensegrity structure and provide upper-bound estimates of viable tensegrity lander designs. A comprehensive range of drop test experiments are conducted to validate the impact behavior and demonstrate the impact-resistance in the highest-altitude drop test experiments of tensegrity landers to date. The experimental results are leveraged to propose empirical scaling laws for the rapid and efficient design of future generations of tensegrity landers. Furthermore, two new tensegrity lander designs, an asymmetrically-weighted structure and a badminton-inspired structure, augment the tensegrity with self-stabilizing functionality to control for the landing orientation of optimal impact mitigation as indicated by the drop test experiment data. The results reveal further opportunities to optimize the design of the structure by aligning the stiffness of the structure with the desired landing orientation. Such a tailored structure can have motorized cables decoupled from the impact event that can then be used to provide locomotion for an ideal hybrid lander-rover tensegrity system.

Overall, the work contributes design methods, reorientation capabilities, and validated hardware prototypes to the grand challenge of tensegrity robotics: demonstrating a fully autonomous tensegrity robot capable of safely navigating through unstructured terrain.

    Cover page: Design of Impact-Resistant Tensegrity Landers
    • Article
    • Peer Reviewed
    UC San Francisco Previously Published Works (2023)
    PURPOSE OF REVIEW: Hip arthroscopy is widely used for the management of intra-articular pathology and there has been growing interest in strategies for management of the hip capsule during surgery. The hip capsule is an essential structure that provides stability to the joint and it is necessarily violated during procedures that address intra-articular pathology. This article reviews different approaches to capsular management during hip arthroscopy including anatomical considerations for capsulotomy, techniques, clinical outcomes, and the role of routine capsular repair. This article also reviews the concept of hip microinstability and its potential impact on capsular management options as well as iatrogenic complications that can occur as a result of poor capsular management. RECENT FINDINGS: Current research highlights the key functional role of the hip capsule and the importance of preserving its anatomy during surgery. Capsulotomies that involve less tissue violation (periportal and puncture-type approaches) do not appear to require routine capsular repair to achieve good outcomes. Many studies have investigated the role of capsular repair following more extensive capsulotomy types (interportal and T-type), with most authors reporting superior outcomes with routine capsular repair. Strategies for capsular management during hip arthroscopy range from conservative capsulotomy techniques aimed to minimize capsular violation to more extensive capsulotomies with routine capsule closure, all of which have good short- to mid-term outcomes. There is a growing trend towards decreasing iatrogenic capsular tissue injury when possible and fully repairing the capsule when larger capsulotomies are utilized. Future research may reveal that patients with microinstability may require a more specific approach to capsular management.
      Cover page: Capsular Management During Hip Arthroscopy.
      • Article
      • Peer Reviewed
      UC San Francisco Previously Published Works (2019)

      Purpose of review

      To assess the outcomes of modern techniques for arthroscopic surgery in the treatment of femoroacetabular impingement.

      Recent findings

      While initially approached by means of open surgical hip dislocation, recent literature has shown generally good outcomes of arthroscopic treatment for femoroacetabular impingement. Modern advances in hip arthroscopy technique and implants now allow for labral repair or reconstruction when indicated. Arthroscopic treatment of femoroacetabular impingement results in significant improvements in patient pain and function, with low complication rates and high patient satisfaction. A majority of improvements in these patients occur within 1 to 2 years post-operatively. Hip arthroscopy for femoroacetabular impingement yields the best results in patients without significant arthritis or hip dysplasia.
        Cover page: Outcomes for Surgical Treatment of Femoroacetabular Impingement in Adults
        • Article
        • Peer Reviewed
        UC San Francisco Previously Published Works (2024)
        Medial patellofemoral ligament (MPFL) reconstruction is a commonly performed procedure to reestablish the checkrein to the lateral patellar translation in patients with recurrent patellofemoral instability. Graft tensioning is one of the most critical aspects of the procedure. Most surgical methods for MPFL reconstruction involve tensioning and securing the graft on the femoral side. In this article, we describe a technique for patellar-sided tensioning of the graft using all-suture anchors, which provides the surgeon with the ability to finely control graft tension with two independent graft limbs, while preserving patellar bone stock.
          Cover page: Minimally Invasive Medial Patellofemoral Ligament Reconstruction With Patellar-Sided Tensioning Using All-Suture Anchors.
          • Article
          • Peer Reviewed
          UC San Francisco Previously Published Works (2024)
          PURPOSE: To evaluate patient-reported outcomes and risk for rerupture after surgical treatment of proximal hamstring tendon ruptures using all-suture anchors and a unique postoperative bracing strategy. METHODS: A retrospective review of a prospectively collected database was conducted of patients undergoing proximal hamstring repair or reconstruction from 2020 to 2022 at a tertiary, academic institution. Patients were included if they reached minimum 1-year follow-up and completed postoperative patient-reported outcomes. The surgical protocol for proximal hamstring repairs included all-suture anchors placed either in an open or endoscopic fashion in the ischial tuberosity. After surgery, all patients underwent an accelerated rehabilitation protocol, including 6 weeks touchdown weight-bearing in a hinged knee brace locked in extension for ambulation, allowing passive knee flexion to 90° while seated. Descriptive statistics were used to analyze the data. RESULTS: Twenty-one patients were included (mean age 50.4 ± 9.5 years, body mass index 24.4 ± 3.5, 66.7% female). Lower Extremity Functional Scale score achieved postoperatively was 74.2 ± 7.5 (out of 80). Patients had minimal pain (mean visual analog scale pain score of 0.9 ± 1.2). 61.9% of patients were able to return to the same level of activity after based on Tegner score by 1 year. Postoperative Single Assessment Numeric Evaluation activity of daily living was 94.3 ± 8.3, and Single Assessment Numeric Evaluation Sports was 82.3 ± 19.0. Mean Short Form Survey (SF-12) postoperative scores were 51.6 ± 6.8 for SF-12 Physical Component Score and 53.9 ± 9.7 for Mental Component Score. 95.2% (20 of 21) patients were satisfied with their outcome. There were no reruptures, infections, or reoperations. One patient of 21 (4.8%) incurred a postoperative deep venous thrombosis, which was treated with therapeutic anticoagulation for 3 months. CONCLUSIONS: All-suture anchors for proximal hamstring repair with a unique accelerated postoperative rehabilitation and bracing protocol result in good outcomes and patient satisfaction with minimal risk of complications. LEVEL OF EVIDENCE: Level IV, case series, therapeutic.
            Cover page: Proximal Hamstring Repair With All-Suture Anchors and an Accelerated Rehabilitation and Bracing Protocol Demonstrates Good Outcomes at 1-Year Follow-Up.
            • Article
            • Peer Reviewed
            UC San Francisco Previously Published Works (2018)

            Background

            Hip arthroscopic surgery is a rapidly growing procedure, but it may be associated with a steep learning curve. Few studies have used patient-reported outcome (PRO) surveys to investigate the relationship between surgeon experience and patient outcomes after the arthroscopic treatment of femoroacetabular impingement (FAI).

            Hypothesis

            Patients undergoing hip arthroscopic surgery for the treatment of FAI in the early stages of a surgeon's career will have significantly worse outcomes and longer procedure times compared with patients treated after the surgeon has gained experience.

            Study design

            Cohort study; Level of evidence, 2.

            Methods

            Patients undergoing hip arthroscopic surgery for FAI and labral injuries were prospectively enrolled during a sports medicine fellowship-trained surgeon's first 15 months of practice. Patients were stratified into an early group, consisting of the first 30 consecutive cases performed by the surgeon, and a late group, consisting of the second 30 consecutive cases. Radiographic and physical examinations were performed preoperatively and postoperatively. PRO surveys, including the 12-item Short Form Health Survey (SF-12), the modified Harris Hip Score (mHHS), and the Hip disability and Osteoarthritis Outcome Score (HOOS), were administered preoperatively and at a minimum of 1 year postoperatively.

            Results

            There was no difference between the early and late groups for patient age (37.2 ± 11.5 vs 35.3 ± 10.8 years, respectively; P = .489), body mass index (25.6 ± 4.0 vs 25.1 ± 4.5 kg/m2, respectively; P = .615), or sex (P = .465). There was a significantly increased procedure time (119.3 ± 21.0 vs 99.0 ± 28.6 minutes, respectively; P = .002) and traction time (72.7 ± 21.4 vs 59.0 ± 16.7 minutes, respectively; P = .007) in the early group compared with the late group. Mean postoperative PRO scores significantly improved in both groups compared with preoperative values for all surveys except for the SF-12 mental component summary. No differences were found in PRO score improvements or complication rates between the early and late groups.

            Conclusion

            The total procedure time and traction time decrease after a surgeon's first 30 hip arthroscopic surgery cases for FAI and labral tears, but patient outcomes can similarly improve regardless of surgeon experience in the early part of his or her career.
              Cover page: Hip Arthroscopic Surgery for Femoroacetabular Impingement: A Prospective Analysis of the Relationship Between Surgeon Experience and Patient Outcomes
              • Article
              • Peer Reviewed
              UC San Francisco Previously Published Works (2019)
              Hip arthroscopy has become the standard treatment for symptomatic femoroacetabular impingement as patients have shown good outcomes and high satisfaction with this intervention. However, capsular management to gain access for intra-articular procedures remains greatly debated. Capsular closure is advocated particularly in the setting of interportal or T-capsulotomy to avoid complications of instability or nonhealing capsule. We introduce a technique for capsular management through a limited periportal capsulotomy during arthroscopic treatment of femoroacetabular impingement. In using dilation of the anterolateral and mid-anterior portals without completion of a full interportal capsulotomy, the stabilizing iliofemoral ligament is preserved. We have found that periportal capsulotomy provides safe and sufficient access to the hip joint without necessitating capsular closure.
                Cover page: Periportal Capsulotomy: A Technique for Limited Violation of the Hip Capsule During Arthroscopy for Femoroacetabular Impingement
                • Article
                • Peer Reviewed
                UC San Francisco Previously Published Works (2018)
                Intra-articular injection of corticosteroid and anesthetic (CSI) is a useful diagnostic tool for hip pain secondary to labral tears or femoroacetabular impingement (FAI). However, the effectiveness of CSI as a stand-alone treatment for hip pain in adolescents is unknown. The purpose of this study is to evaluate the use of CSI for the treatment of hip pain and determine factors that may affect outcomes after injection. Retrospective analysis of 18 patients and 19 hips that underwent fluoroscopic guided hip injection for the treatment of pain at a single institution from 2012 to 2015 was carried out in this study. Mean age at the time of injection was 15.1 years (range 13-17) with mean follow-up of 29.4 months. Fifty-two percent (10/19 hips) went on to surgery after the injection. Average time to surgical conversion was 12.8 months after CSI. Cam or pincer morphologies were present in 90% (9/10 hips) of the operative group. Patients with FAI were more likely to need surgery than patients without bony abnormalities (RR= 10, 95% CI 1.6-64.2, P = 0.0001). There was no difference in the presence of labral tears in the operative and non-operative groups (100% versus 89%, P = 0.47). For adolescents without bony abnormalities, 90% improved with CSI alone and did not require further treatment within 2.4 years. Fluoroscopic guided corticosteroid hip injection may have limited efficacy for the treatment of hip pain secondary to FAI in adolescents. However, for patients without osseous deformity, CSI may offer prolonged improvement of symptoms even in the presence of labral tears.
                  Cover page: Outcomes of intra-articular corticosteroid injections for adolescents with hip pain
                  • Article
                  • Peer Reviewed
                  UC San Francisco Previously Published Works (2016)
                  Concussion injuries have been highlighted to the American public through media and research. While recent studies have shown increased traumatic brain injuries (TBIs) diagnosed in emergency departments across the United States, no studies have evaluated tr
                    • Article
                    • Peer Reviewed
                    SSOE Research Symposium Dean's Awards (2016)

                    Background: To create a low cost, low power consumption and high accuracy indoor navigation system – iLost that can guide customers from their current location to their destination in building.

                     Faculty Adviser: Prof. Pai H. Chou, Department of Electrical Engineering & Computer Science             phchou@uci.edu

                      Cover page: iLost -- Bluetooth Indoor Navigation System
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