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Biomedical subjects

Graham J W King

Publications and source records attributed to Graham J W King.

At least 19 recordsLinked to original sources
PubMed2007

Plate fixation of olecranon osteotomies.

The management of intra-articular distal humeral fractures remains a difficult surgical problem. Although an olecranon osteotomy provides excellent exposure for management of these fractures, a number of complications can occur after the creation and repair of the osteotomy including nonunion, malunion, hardware failure, and pain secondary to prominent hardware. In an effort to reduce the incidence of these complications, the senior authors now use contoured 3.5 mm reconstruction plates for the fixation of their apex-distal chevron olecranon osteotomies. Two surgeons at a single institution used this technique of exposure on a series of 17 consecutive patients with intra-articular distal humerus fractures between 1996 and 1999. In this series, all osteotomies united. There was one complication related specifically to the osteotomy: one of the screws in the plate penetrated the proximal radioulnar joint, interfering with forearm rotation; a second procedure was required to shorten the screw. Only one of the 17 patients requested plate removal during the 32 month (average) follow-up period. Plate fixation of olecranon osteotomies using a 3.5 mm reconstruction plate provides a construct with predictable healing and few complications. The overall results using this technique are comparable with other reported methods in the literature.

Bone Plates↗
PubMed2006

The effect of coronoid fractures on elbow kinematics and stability.

BACKGROUND: Coronoid fractures often occur in the setting of more complex elbow trauma. Little is known about the influence of coronoid fracture size on elbow kinematics, particularly in the setting of concomitant ligament injuries. The purpose of this study was to determine the effect of coronoid fractures on elbow kinematics and stability in ligamentously intact and medial collateral ligament deficient elbows and to determine the effect of forearm position on elbow stability in the setting of coronoid fracture. METHODS: Eight cadaveric arms were tested during simulated active dependent elbow motion and gravity-loaded passive elbow motion. Kinematic data were collected from an electromagnetic tracking system. The protocol was performed in ligament origin repaired and medial collateral ligament deficient elbows with radial head arthroplasty. Testing was carried out with the coronoid intact, and with 10% (Type I), 50% (Type II), and 90% (Type III) removed. Varus-valgus angulation of the ulna relative to the humerus and maximum varus-valgus laxity were measured. FINDINGS: With repaired ligament origins and medial collateral ligament deficiency, there was increased varus angulation and increased maximum varus-valgus laxity following simulation of a Type II and Type III coronoid fracture. There was less kinematic change with the forearm in supination than in pronation. INTERPRETATION: Elbow kinematics are altered with increasing coronoid fracture size. Repair of Type II and Type III coronoid fractures as well as lateral ligament repair is recommended where possible. Forearm supination may be considered during rehabilitation following coronoid repair. Valgus elbow positioning should be avoided if the medial collateral ligament is not repaired.

Aged↗
PubMed2006

Glenoid vault endosteal dimensions: an anthropometric study with special interest in implant design.

An understanding of the morphology of the glenoid is important from the viewpoint of implant design and selection. This study describes the endosteal dimensions and shape of the glenoid and correlates these results with age, gender, and the presence of osteoarthritis. This study used 72 scapulae. Data were obtained from computed tomography scans of both cadaveric and in vivo glenoids. The glenoid is relatively straight-sided in the coronal plane and more highly fluted in the transverse plane. The endosteal dimensions were larger for male specimens, but there was no difference in endosteal shape with respect to gender. These findings were not influenced by age or the presence of osteoarthritis. This study suggests that traditional glenoid component designs may not be optimal. To maximize fixation, a rectangular keel may be most effective in the coronal plane and a triangular keel may be most effective in the transverse plane.

Adult↗
PubMed2006

Effect of simulated muscle activity on distal radioulnar joint loading in vitro.

This study investigated the relationship between simulated forearm muscle loads and the joint reaction force in the distal radioulnar joint using an in vitro model. Seven fresh frozen cadaveric specimens were mounted in an upper extremity joint simulator capable of applying pneumatic loads to various (muscle) tendons while restraining the forearm in the three positions of pronation, supination, and neutral rotation. Loads were applied to model four forearm muscles (biceps, pronator teres, pronator quadratus, and supinator) in 10 N increments ranging from 10 N to 80 N for the biceps and pronator teres and in 10 N increments from 10 N to 50 N for the pronator quadratus and the supinator. Distal ulnar arthroplasty was performed on each specimen with a custom instrumented ulnar head replacement implant that quantified loads (via strain gauge instrumentation). The relationship between increasing muscle load and joint load was found to be positive and quasilinear in most cases. The biceps had the greatest influence on the distal radioulnar joint reaction force with a joint force in the range of 8% to 33% of the applied muscle load. The pronator teres, supinator, and pronator quadratus were less influential with a joint reaction force ranging between 6% to 19%, 4% to 9% and 2% to 10% of the applied muscle load, respectively.

Aged↗
PubMed2006

Functional outcomes of arthroscopic capsular release of the elbow.

PURPOSE: Elbow contracture is a common and difficult problem to manage. The purpose of this study was to determine the functional outcomes of arthroscopic capsular release in the management of elbow contractures. METHODS: A total of 22 patients (14 males, 8 females; mean age, 42 years) undergoing arthroscopic contracture release were retrospectively reviewed at a minimum follow-up of 1 year (mean, 25 months). In all, 20 patients had a capsulectomy, and 2 underwent capsulotomy. Patient-rated questionnaires (Disability of the Arm, Shoulder, and Hand questionnaire [DASH], American Shoulder and Elbow Surgeons Elbow Form [ASES-e], and Short Form-36 [SF-36]) and clinical, radiographic, and objective evaluations were used to assess outcomes. Motion and strength were measured by independent evaluators through standard goniometry and the LIDO Isokinetic System (Loredan Biomedical, West Sacramento, CA). RESULTS: Mean flexion significantly improved from 122 degrees +/- 15 degrees to 141 degrees +/- 12 degrees (P < .001). Mean extension significantly improved from 38 degrees +/- 18 degrees to 19 degrees +/- 13 degrees (P < .001). Mean arc improvement was 38 degrees +/- 23 degrees (P < .001). None of the patients had instability, and no major neurovascular complications were reported. All patients had improved elbow function with a mean ASES-e score of 31 out of 36. Most patients were satisfied with their surgery, experienced minimal pain, and exhibited minimal impairment on the DASH. CONCLUSIONS: Arthroscopic debridement and capsulectomy of the contracted elbow is effective. Results are comparable with those of other reports in the literature in which both arthroscopic and open methods were used. LEVEL OF EVIDENCE: Level IV.

Adolescent↗
PubMed2006

Design and implementation of an instrumented ulnar head prosthesis to measure loads in vitro.

The development of a novel instrumented implant for ulnar head replacement is presented in this study. This implant was instrumented with strain gauges to quantify bending moments about the anatomic axes of the distal ulna, and subsequently the distal radioulnar joint (DRUJ) reaction force magnitude. The implant was surgically inserted in seven cadaveric upper extremities, which were subsequently mounted in a custom joint simulator. Simulated active unresisted pronation and supination motion trials were conducted using computer-controlled pneumatic actuators to simulate forearm musculature. Passive (unloaded) trials were also conducted. The reaction force across the DRUJ ranged from 2 to 10 N in magnitude during this unresisted motion. Increased bending moment magnitudes were measured when the forearm was positioned in supination compared to pronation. The magnitude of joint bending moments showed a consistent pattern with forearm position, regardless of simulated active or passive rotation, or supination and pronation motion trials. This result illustrates that the primary influence on joint load is likely the position and contact with the radial articulation. This study of DRUJ loading should be useful for biomechanical modeling, implant design considerations and improved knowledge of articular mechanics.

Aged↗
PubMed2006

Outcome after open reduction and internal fixation of capitellar and trochlear fractures.

BACKGROUND: Capitellar and trochlear fractures are uncommon fractures of the distal aspect of the humerus. There is limited information about the functional outcome of patients managed with open reduction and internal fixation. METHODS: The functional outcome of twenty-eight patients, with a mean age (and standard deviation) of 43 +/- 13 years, who were treated with open reduction and internal fixation for capitellar and trochlear fractures was evaluated at a mean duration of follow-up of 56 +/- 33 months. Patient outcomes were assessed with physical and radiographic examination, range-of-motion measurements, strength testing, and self-reported questionnaires (Short Form-36, Mayo Elbow Performance Index, American Shoulder and Elbow Surgeons Elbow Assessment Form, and Patient-Rated Elbow Evaluation scales). RESULTS: Eleven fractures involved the capitellum with or without fracture of the lateral ridge of the trochlea, four involved the capitellum and trochlea as one piece, and thirteen involved the capitellum and trochlea as separate fragments. These fractures were further characterized by the presence or absence of posterior comminution. Fourteen patients had isolated fractures, and fourteen had other elbow, forearm, or wrist injuries. Patients with more complex fractures required more extensive surgery, had more complications resulting in secondary procedures, and had poorer outcomes compared with those with simple fractures. The average score on the Mayo Elbow Performance Index (91 +/- 11), the average quality-of-life scores (46 on the physical component and 50 on the mental component of the Short Form-36), and the average range of motion (19 degrees to 138 degrees ) suggest favorable patient outcomes overall. Two comminuted fractures did not unite and required conversion to a total elbow arthroplasty. CONCLUSIONS: Patients with isolated noncomminuted capitellar and/or trochlear fractures have better results than those with more complex fractures. A classification system based on the radiographic patterns of these fractures is recommended.

Adult↗
PubMed2006

Comminuted radial head fractures treated with a modular metallic radial head arthroplasty. Study of outcomes.

BACKGROUND: Comminuted fractures of the radial head are challenging to treat with open reduction and internal fixation. Radial head arthroplasty is an alternative treatment with results that compare favorably with those reported after open reduction and internal fixation of similar fractures. The purpose of this study was to evaluate the two-year outcomes and the rate of recovery of a closely followed cohort of patients in whom an unreconstructible radial head fracture had been treated with a modular metallic prosthesis. METHODS: Twenty-six patients (seventeen female and nine male; mean age, fifty-four years) with an unreconstructible comminuted radial head fracture and associated elbow injuries were treated with a modular metallic radial head arthroplasty. Patients who had presented more than four weeks following the injury or had had the radial head arthroplasty as a second-stage or salvage procedure were excluded. Of the twenty-six patients, twenty-two had an associated elbow dislocation, and thirteen of them also had an associated fracture of the coronoid process. Patients were prospectively followed at three, six, twelve, and twenty-four months. Self-reported limb function, general health, range of motion, and isometric strength were assessed by an independent observer. RESULTS: Following treatment of the injury, significant decreases in self-reported and measured impairments were noted over time, with the majority of the recovery occurring by six months and little further recovery noted between six and twenty-four months. There were slight-to-moderate deficits in the range of motion and strength compared with the values on the contralateral, unaffected side. Patient satisfaction was high at three months and remained high at two years. All elbow joints remained stable, no implant required revision, and there was no evidence of overstuffing of the joint. Mild osteoarthritis was seen in five (19%) of the twenty-six patients. CONCLUSIONS: An arthroplasty with a modular metallic radial head is a safe and effective option for the treatment of unreconstructible radial head fractures associated with other elbow injuries. Recovery primarily occurs by six months, with minimal additional improvements over the next eighteen months.

Adult↗
PubMed2006

Arthroscopic treatment of the arthritic elbow.

Elbow arthroscopy is now being used with greater frequency to treat arthritis and contractures. The procedure is technically demanding and the potential for injury to neurovascular structures remains a concern. Potential advantages of arthroscopic treatment include improved articular visualization and decreased postoperative pain. Patients may also benefit from decreased morbidity and a faster postoperative recovery. Elbow arthroscopy can be performed for removal of loose bodies, resection of symptomatic plica, release of the capsule in patients with contracture, removal of osteophytes, treatment of synovectomy in inflammatory arthritis, treatment of osteochondritis dissecans, débridement of lateral epicondylitis, and treatment of elbow fractures.

Arthritis↗
PubMed2005

Cyclic loading of rotator cuff repairs: an in vitro biomechanical comparison of bioabsorbable tacks with transosseous sutures.

PURPOSE: This study compares rotator cuff repair strength after cyclic loading of bioabsorbable tacks and traditional transosseous sutures, and correlates the results with bone density, age, and gender. The hypotheses were that tack repair strength would be inferior to transosseous sutures and that repair strength would be directly related to bone quality. TYPE OF STUDY: In vitro randomized biomechanical study. METHODS: Eight paired cadaveric shoulders with a standardized supraspinatus defect were randomized to tack or suture repair and subjected to step-wise cyclic loading. Repair migration was measured by quantifying the motion of markers affixed to tendon and bone using a digital camera. Failure mode, cycles, and load were measured for 50% and 100% loss of repair. Results were correlated with bone density, age, and gender. RESULTS: Tack repairs failed at the tack-tendon interface, whereas suture rupture was the mode of failure for the suture repairs. Mean values for 50% loss of repair were 206 +/- 88 cycles and 44 +/- 15 N for the sutures, and 1,193 +/- 252 cycles and 156 +/- 20 N for the tacks (P < .05). The corresponding values for 100% loss of repair were 2,458 +/- 379 cycles and 294 +/- 27 N for the sutures, and 2,292 +/- 333 cycles and 263 +/- 28 N for the tacks (P > .05). These results did not correlate with bone density, age, or gender. CONCLUSIONS: This study has shown that bioabsorbable tacks provide improved repair strength in comparison with traditional suture techniques. Repair strength did not correlate with bone quality, and this may be attributed to failure primarily through the repair construct or at the tack-tendon interface and not through bone. This report describes a new high-resolution optical method of measuring tendon repair strength that should be a useful model for future studies. CLINICAL RELEVANCE: This study demonstrates the biomechanical advantages of a sutureless tack device for rotator cuff repair compared with a traditional augmented suture repair technique.

Absorbable Implants↗
PubMed2005

Comparison of distal radioulnar joint reconstructions using an active joint motion simulator.

PURPOSE: Distal radioulnar joint (DRUJ) instability can result in pain and functional disability. Numerous DRUJ reconstructive options have been described with minimal biomechanical analysis. The purpose of this study was to evaluate the ability of 4 well-described DRUJ reconstructions to restore joint kinematics using a dynamic, motion-controlled simulator. METHODS: Eleven cadaveric upper extremities had computer-controlled simulated active forearm rotation. Joint kinematics were quantified by using an electromagnetic tracking system. We compared the passive and simulated active kinematics of the intact, unstable, and reconstructed DRUJ (capsular repair, 2 described radioulnar ligament reconstructions, and a radioulnar tethering procedure). RESULTS: All reconstructions improved significantly the kinematics of the unstable DRUJ. The capsule repair restored simulated active joint kinematics closest to the intact DRUJ. CONCLUSIONS: All 4 reconstructions improved DRUJ stability significantly. The capsule repair most closely matched intact DRUJ kinematics and the radioulnar ligament reconstructions were found to be superior to a radioulnar tethering procedure.

Adult↗
PubMed2005

Comparison of sagittal computed tomography and plain film radiography in a scaphoid fracture model.

PURPOSE: To compare computed tomography (CT) in the sagittal plane and plain film radiography in the diagnosis of scaphoid fracture and displacement. METHODS: Three groups of scaphoids (no fracture, undisplaced fractures, fractures with displacement > 1 mm) from 11 cadaver wrists were prepared. Each wrist then was imaged by using sagittal plane CT scans in the long axis of the scaphoid and plain film imaging using 6 standard scaphoid views. Eight readers from 3 specialties read each group of images. The sensitivity and specificity for the presence of fracture and fracture displacement were calculated in addition to interobserver and intraobserver reliabilities for each. RESULTS: Both x-ray and CT scans showed a high sensitivity and specificity in detecting the presence of a fracture with no interspecialty differences. The sensitivity for displacement greater than 1 mm was lower for both modalities with no inter-specialty differences. The specificities for x-ray and CT for detecting displacement greater than 1 mm were 84% and 89%, respectively. The poor sensitivity for detecting displacement was explained by the low sensitivity of CT in the diagnosis of radial/ulnar displacement compared with x-ray and the low sensitivity of x-ray in the diagnosis of volar/dorsal displacement compared with CT scans. When fellowship-trained hand surgeons reviewed CT scans and plain films together the sensitivity and specificity for fracture displacement increased significantly. Intraobserver and interobserver reliability for both x-ray and CT scans was excellent except for the reading of CT scans among emergency physicians and for the reading of plain x-rays among senior house staff, representing moderate agreement. CONCLUSIONS: Based on these results both CT scans in the sagittal plane and plain films accurately detect fractures with a high degree of interobserver and intraobserver reliability, but they fall short in detecting displacement greater than 1 mm.

Aged↗
PubMed2005

The effect of radial head fracture size on elbow kinematics and stability.

This study determined the effect of radial head fracture size and ligament injury on elbow kinematics. Eight cadaveric upper extremities were studied in an in vitro elbow simulator. Testing was performed with ligaments intact, with the medial collateral (MCL) or lateral collateral (LCL) ligament detached, and with both the MCL and LCL detached. Thirty degree wedges were sequentially removed from the anterolateral radial head up to 120 degrees . Valgus angulation and external rotation of the ulna relative to the humerus were determined for passive motion, active motion, and pivot shift testing with the arm in a vertical (dependent) orientation. Maximum varus-valgus laxity was calculated from measurements of varus and valgus angulation with the arm in horizontal gravity-loaded positions. No effect of increasing radial head fracture size was observed on valgus angulation during passive and active motion in the dependent position. In supination, external rotation increased with increasing fracture size during passive motion with LCL deficiency and both MCL and LCL deficiency. With intact ligaments, maximum varus-valgus laxity increased with increasing radial head fracture size. With ligament disruption, elbows were grossly unstable, and no effect of increasing radial head fracture size occurred. During pivot shift testing, performed with the ligaments intact, subtle instability was noted after resection of one-third of the radial head. In this in vitro biomechanical study, small subtle effects of radial head fracture size on elbow kinematics and stability were seen in both the ligament intact and ligament deficient elbows. These data suggest that fixation of displaced radial head fractures less than or equal to one-third of the articular diameter may have some biomechanical advantages; however, clinical correlation is required.

Aged↗
PubMed2005

Elbow arthroplasty using a convertible implant.

Total elbow arthroplasty remains the most definitive functional procedure for patients with end-stage painful arthritis of the elbow. Complication rates have historically been quite high, and early revision was not uncommon. A greater understanding of elbow anatomy and kinematics has led to advances in prosthetic design and surgical technique. The success of modern elbow arthroplasty for low-demand patients with rheumatoid arthritis has approached that of hip and knee arthroplasty. Mechanical failures have been noted to increase as a complication of both longevity and the use of elbow arthroplasty in a younger, higher-demand patient population. As the indications for total elbow arthroplasty widen to include more complex situations, it becomes more important to precisely recreate the flexion-extension axis of the elbow to optimally balance muscle forces and ligaments in an effort to improve implant durability. Advances in implant modularity and instrumentation can make determination and recreation of the flexion-extension axis more reliable and reproducible. An anatomic convertible implant allows the surgeon great versatility in choosing to perform hemiarthroplasty or unlinked or linked total elbow arthroplasty with assurance that later revision can be performed without the compulsory removal of well-fixed components. Conversion from an unlinked to a linked constraint, and visa versa, can be performed at any time. If late conversion is required, it can be performed in a minimally invasive fashion.

Arthritis↗
PubMed2005

Standard surgical protocol to treat elbow dislocations with radial head and coronoid fractures. Surgical technique.

BACKGROUND: The results of elbow dislocations with associated radial head and coronoid fractures are often poor because of recurrent instability and stiffness from prolonged immobilization. We managed these injuries with a standard surgical protocol, postulating that early intervention, stable fixation, and repair would provide sufficient stability to allow motion at seven to ten days postoperatively and enhance functional outcome. METHODS: We retrospectively reviewed the results of this treatment performed, at two university-affiliated teaching hospitals, in thirty-six consecutive patients (thirty-six elbows) with an elbow dislocation and an associated fracture of both the radial head and the coronoid process. Our surgical protocol included fixation or replacement of the radial head, fixation of the coronoid fracture if possible, repair of associated capsular and lateral ligamentous injuries, and in selected cases repair of the medial collateral ligament and/or adjuvant-hinged external fixation. Patients were evaluated both radiographically and with a clinical examination at the time of the latest follow-up. RESULTS: At a mean of thirty-four months postoperatively, the flexion-extension arc of the elbow averaged 112 degrees +/- 11 degrees and forearm rotation averaged 136 degrees +/- 16 degrees . The mean Mayo Elbow Performance Score was 88 points (range, 45 to 100 points), which corresponded to fifteen excellent results, thirteen good results, seven fair results, and one poor result. Concentric stability was restored to thirty-four elbows. Eight patients had complications requiring a reoperation: two had a synostosis; one, recurrent instability; four, hardware removal and elbow release; and one, a wound infection. CONCLUSIONS: Use of our surgical protocol for elbow dislocations with associated radial head and coronoid fractures restored sufficient elbow stability to allow early motion postoperatively, enhancing the functional outcome. We recommend early operative repair with a standard protocol for these injuries.

Collateral Ligaments↗
PubMed2004

Internal fixation of radial neck fractures: an in vitro biomechanical analysis.

OBJECTIVE: To assess the fixation rigidities of a custom designed blade plate, a 2.7 mm T-plate and 3.0 mm cannulated screws. DESIGN: A cadaveric non-comminuted radial neck fracture model was employed to test the three fixation methods, using a multi-directional shear loading protocol. BACKGROUND: The management of displaced radial neck fractures in adults remains unsatisfactory due to failure of internal fixation with secondary loss of reduction, and non-unions. METHODS: The stiffness of the various fixation methods was measured in five directions of loading in the transverse plane. Failure testing was performed on the final testing condition for each specimen, in a posteroulnar to anteroradial direction. RESULTS: The direction of specimen loading did not have a significant effect on the stiffness of the various methods of fixation (P = 0.4). There was no significant difference in the fixation stiffness between the 3.0 mm screws or blade plate, however, both were superior to the T-plate (P < 0.05). CONCLUSIONS: Although the 2.7 mm T-plate has been reported in the literature as a viable method of fixation for radial neck fractures, it may not be optimal from the viewpoint of fixation stability. In the setting of a non-comminuted radial neck fracture, the use of cross-cannulated screws or blade plate fixation is preferred.Relevance This study supports the use of cross-cannulated screws or blade plate fixation for non-comminuted fractures of the radial neck.

Aged↗