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BACKGROUND: Total shoulder replacement surgery has been a successful treatment for patients with shoulder arthritis. However, long-term results are limited by complications such as glenoid loosening, wear, and instability. Also, glenoid bone deficiency limits available treatment options and outcomes. Successful short-term outcomes have been reported previously using inset glenoid implants for deficient arthritic bone, but long-term outcomes have not been reported using this technique. METHODS: A retrospective analysis was performed on 21 of 24 consecutive patients treated with inset glenoid implants for severe glenohumeral joint arthritis with bone deficiency with prospectively collected data. Inclusion criteria were patients with shoulder arthritis and severe glenoid bone deficiency, defined by perpendicular glenoid vault depth less than 15 mm. No bone grafts were used. All patients were evaluated preoperatively and after surgery with physical examination, radiographic studies, and outcome measures. There were 10 males and 11 females, 17 cases with osteoarthritis and 4 with inflammatory arthritis, and 5 patients with rotator cuff tears (3 full thickness and 2 partial tears). Mean age was 68 years. RESULTS: There were no surgical complications. At a mean follow-up of 8.7 years, there were statistically significant improvements (P < .001) in visual analog pain scores (7.7 to 0.1), American Shoulder and Elbow Surgeons outcome scores (23 to 95), and range of motion. There were no loose glenoids. No patients required any revision surgery. CONCLUSIONS: This study documents the long-term efficacy and safety of total shoulder replacement surgery with inset glenoid implants used to reconstruct deficient, arthritic glenoid bone.

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BACKGROUND: The longevity of total shoulder replacement is primarily limited by the performance of the ultrahigh-molecular-weight polyethylene (UHMWPE) glenoid component in vivo. Variations in glenoid design (conformity, thickness), biomechanics (joint kinematics), and UHMWPE material selection (sterilization, cross-linking) distinguish total shoulder replacements from hip and knee arthroplasty devices. These variables can lead to severe mechanical failures, including gross fracture. METHODS: Sixteen retrieved glenoids with severe fracture were analyzed. The explant cohort included 3 material groups (gamma-sterilized Hylamer; gamma-sterilized UHMWPE; and gas plasma-sterilized, remelted, highly cross-linked UHMWPE [HXL]) and a range of conformities (0- to 10-mm radial mismatch). Analysis included fractography (optical and scanning electron microscopy) and Fourier transform infrared spectroscopy for oxidative analysis. RESULTS: Fracture primarily occurred along the exterior rim for all 16 explants. Fourier transform infrared analysis and fractography revealed significant oxidative embrittlement for all gamma-sterilized glenoids. Fatigue striations and internal flaws were evident on the fracture surface of the HXL glenoid, with little oxidation detected. CONCLUSIONS: Fracture initiated at the external rim of all devices. Elevated oxidation levels and visible material distortion for representative gamma-sterilized conventional and Hylamer devices suggest oxidative embrittlement as a driving force for crack inception and subsequent fracture. Brittle fracture of theHXL glenoid resulted from a combination of elevated contact stress due to a nonconforming surface, an internal flaw, and reduced resistance to fatigue crack growth. This demonstrates that glenoid fracture associated with oxidation has not been eliminated with the advent of modern materials (HXL) in the shoulder domain. LEVEL OF EVIDENCE: Basic Science Study; Implant Retrieval Study.

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Distal radius fractures, the most common long bone fracture, are treated in several ways, including closed reduction, percutaneous pinning, external fixation, and open reduction and internal fixation. This article presents a surgical technique and a series of patients treated with a novel minimally invasive intramedullary fixation technique. The implant is a partially flexible intramedullary rod that can be locked in a rigid position once it is implanted in the bone. An awl and reamer are passed through a starter hole in the radial styloid using a 2-cm incision between the 1st and 2nd dorsal compartments. The device is then implanted under the articular surface, and the distal end of the curved implant is placed down the intramedullary canal of the radius. After locking the shaft segment rigidly, screws are placed through the implant under the distal radial articular margin to stabilize the fracture site. The sensory branches of the radial nerve are retracted during the case. Patients are treated in a wrist splint for a short period of time (2 to 4 weeks) depending on fracture type. The case examples demonstrate the minimally invasive nature of this procedure, the surgical technique, methods of fracture reduction and implantation, and surgical outcomes. Radiographic outcomes, postoperative motion, postoperative function, and validated outcome measures are demonstrated. This minimally invasive technique is ideally suited for distal radial fractures that do not involve the articular surface. It is a safe and effective technique that can provide excellent results.

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BACKGROUND: Treatment of patients with shoulder arthritis and severe glenoid bone loss is controversial. Medial and posterior bone loss limits the size of the glenoid vault, which is the structural support of all current glenoid designs. This study presents short-term outcomes of a treatment using inset glenoid implants during shoulder replacement surgery in deficient glenoid bone. METHODS: This study presents short-term outcomes of total shoulder replacement surgery using custom inset glenoid implants in deficient glenoid bone. Seven consecutive patients (3 men, 4 women; mean age 70 years) treated with inset glenoid implants for severe bone deficiency were retrospectively evaluated at a minimum 3-year follow-up. Severely deficient bone was defined by a neutral glenoid vault depth of less than 15 mm. No bone grafts were used. All patients were evaluated before and after surgery with physical examination, radiographic studies, and outcome measures. All patients had a diagnosis of osteoarthritis. No patients had rotator cuff tears or a history of instability. RESULTS: No surgical complications occurred. At an average of 4.3 years, the mean American Shoulder and Elbow Surgeon score improved 68 points. There were statistically significant improvements in range of motion (forward flexion 33°, external rotation 34°, internal rotation 6 spinal levels) and in pain (6.9 to 0.1). Independent radiographic analysis determined all implants were classified as "low risk" for glenoid loosening. DISCUSSION: The treatment of shoulder arthritis with severe glenoid bone loss is controversial and the results are mixed. Current treatments consist of hemiarthroplasty with or without glenoid reaming, total shoulder replacement without version correction, and total shoulder replacement with bulk bone grafting and version correction. The surgical technique and clinical results described in this case series demonstrate a novel approach of inset glenoid fixation for severely deficient bone. CONCLUSIONS: This study documents for the first time the possibility of safely and effectively using inset glenoid implants to reconstruct deficient bone for which standard implants are contraindicated.

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HYPOTHESIS: The success of shoulder arthroplasty surgery has been limited by a common complication: glenoid implant loosening. Eccentric loading of the glenoid due to migration of the humeral head is considered to be the major cause of glenoid loosening and is referred to as the rocking-horse phenomenon. Glenoid implant loosening may cause pain, limitation of function, and the need for complicated revision surgery. Our hypothesis was that an inset fixation technique could offer increased fixation strength and minimize the effects of the rocking-horse phenomenon on glenoid loosening. MATERIALS AND METHODS: Fixation strength and stress distribution were analyzed using two methods. First, mechanical simulation of physiologic in vivo cyclic loading was performed on 1 inset glenoid implant design and 2 standard onlay glenoid implant designs currently on the market. Second, 3-dimensional finite element analysis was performed to compare an inset glenoid implant and a standard onlay glenoid implant with a keel and a standard onlay pegged implant. RESULTS: After cyclic loading to 100,000 cycles, no glenoid implants demonstrated signs of loosening. Mechanical testing after cyclic loading demonstrated less distraction of the glenoid rim using an inset technique compared with an onlay technique. Finite element analysis results indicated that the inset technique achieved up to an 87% reduction in displacement. CONCLUSIONS: Mechanical tests and finite element analysis support the concept of inset glenoid fixation in minimizing the risk of glenoid loosening.

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Twenty-six patients who presented to our shoulder service with a symptomatic meso-os acromiale were reviewed. All had been initially treated for impingement symptoms. Nonoperative treatment had failed in all patients. One patient had also undergone an arthroscopic acromioplasty without benefit. The diagnosis of symptomatic os acromiale was made on the basis of radiographs and point tenderness over the acromion coupled with signs of rotator cuff pathology. We assessed these patients after treatment by internal fixation and bone grafting. Fixation was achieved with either K-wires or screws and tension banding with either wire or suture. Fifteen patients had associated rotator cuff tears. The clinical and radiologic results are reported. The rate of union was 96% (25/26), and 24 of 26 patients (92%) were satisfied with their results. The mean time to union was 4 months. There were two postoperative fractures. Eight patients (thirty-one percent) had postoperative pain that was subsequently relieved by wire or screw removal. Seventeen patients had concomitant rotator cuff tears. Eleven cuff tears were repaired, and six were irreparable. One of these six was extensively debrided. We conclude that open reduction-internal fixation of the symptomatic meso-acromion yields satisfactory results, and with the exception of hardware discomfort necessitating removal, minimal complications arise in the majority of cases.

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OBJECTIVE: Current surgical training programs in the United States are based on an apprenticeship model. This model is outdated because it does not provide conceptual scaffolding, promote collaborative learning, or offer constructive reinforcement. Our objective was to create a more useful approach by preparing students and residents for operative cases using interactive computer simulations of surgery. Total-knee-replacement surgery (TKR) is an ideal procedure to model on the computer because there is a systematic protocol for the procedure. Also, this protocol is difficult to learn by the apprenticeship model because of the multiple instruments that must be used in a specific order. We designed an interactive computer tutorial to teach medical students and residents how to perform knee-replacement surgery. We also aimed to reinforce the specific protocol of the operative procedure. Our final goal was to provide immediate, constructive feedback. DESCRIPTION: We created a computer tutorial by generating three-dimensional wire-frame models of the surgical instruments. Next, we applied a surface to the wire-frame models using three-dimensional modeling. Finally, the three-dimensional models were animated to simulate the motions of an actual TKR. The tutorial is a step-by-step tutorial that teaches and tests the correct sequence of steps in a TKR. The student or resident must select the correct instruments in the correct order. The learner is encouraged to learn the stepwise surgical protocol through repetitive use of the computer simulation. Constructive feedback is acquired through a grading system, which rates the student's or resident's ability to perform the task in the correct order. The grading system also accounts for the time required to perform the simulated procedure. We evaluated the efficacy of this teaching technique by testing medical students who learned by the computer simulation and those who learned by reading the surgical protocol manual. Both groups then performed TKR on manufactured bone models using real instruments. Their technique was graded with the standard protocol. The students who learned on the computer simulation performed the task in a shorter time and with fewer errors than the control group. They were also more engaged in the learning process. DISCUSSION: Surgical training programs generally lack a consistent approach to preoperative education related to surgical procedures. This interactive computer tutorial has allowed us to make a quantum leap in medical student and resident teaching in our orthopedic department because the students actually participate in the entire process. Our technique provides a linear, sequential method of skill acquisition and direct feedback, which is ideally suited for learning stepwise surgical protocols. Since our initial evaluation has shown the efficacy of this program, we have implemented this teaching tool into our orthopedic curriculum. Our plans for future work with this simulator include modeling procedures involving other anatomic areas of interest, such as the hip and shoulder.

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There have been many reports describing modes of damage in retrieved total hip and total knee arthroplasty components. The most common mechanism in total hip arthroplasties has been shown to be surface wear. Fatigue failure shown as pitting and delamination are observed more often in total knee components. There has been no previous analysis of retrieved polyethylene glenoid components. This study evaluated the wear mechanisms contributing to failure of total shoulder glenoid components. Polyethylene glenoid components from 10 consecutive total shoulder arthroplasties have been retrieved and analyzed. Wear mechanisms were analyzed under low-power magnification, and a classification system was designed for total shoulder arthroplasties. This classification system is an adaptation of previous models of hip and knee surface damage. The severity of each damage mode was graded in 4 separate quadrants. The most prevalent damage modes were abrasion, pitting, and delamination. These data show a combination of abrasive wear and fatigue in retrieved total shoulder specimens. Surface wear and subsurface fatigue failure mechanisms both contribute to glenoid implant failure.

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