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PubMed1985

Stress analyses of joint arthroplasty in the proximal humerus.

Finite element stress analyses were performed on the proximal humerus before and after the simulated implantation of stemmed, metallic prosthetic components with porous sintered surfaces for direct bony attachment. Design geometries with surfaces at the prosthetic head/bone interface that were (a) convex, (b) flat, and (c) concave were studied. Analyses for each of the three geometries were conducted to reflect (a) bone ingrowth on all the prosthesis/bone surfaces and (b) bone ingrowth only along the underside of the prosthetic humeral head (assuming the stem was not coated with a porous material). Three loading conditions were used to model various degrees of abduction of the arm. Results indicated that in the normal humerus the compressive joint forces are transmitted from the articular surface through cancellous bone to the inferior cortical shell. Contraction of the rotator cuff muscles created tensile stresses in the superolateral cancellous bone and the superior cortical shell of the humerus. Results of the implanted humeral component models indicated that the use of a prosthesis with bone ingrowth along the stem would cause marked stress shielding proximally whereas the use of implants with porous ingrowth only on the underside of the humeral head replacement produced stress fields more similar to the normal humerus. The convex, flat, and concave surfaces provided similar load transfer from the component to the underlying bone in all loading cases. Other prosthetic head designs that may offer better initial stability produced stress fields similar to those of existing prostheses.

Biomedical Engineering↗
PubMed1986

Bone cortical mass in newborn infants: a comparison between standards in the femur and humerus.

The total bone width (T) and medullary width (M) of the humerus and femur of 216 and 138 Nigerian newborn infants, respectively, were measured in order to determine the normal standards for cortical bone mass in the newborn. The cortical width (C), cortical area (CA), and percentage cortical area (PCA) were calculated for each bone and correlated with gestational age and birth weight. In both the femur and humerus, the values of the cortical measurements were higher in males. The strongest correlation coefficients were obtained between T(0.84), C(0.79), and CA(0.84) and birth weight in the humerus. The correlation with gestational age was, however, similar in both bones. The values of humeral cortical width (C) obtained in this study is less than had been reported in North American white newborn infants. Cortical measurements of the humerus, which is invariably included in the newborn chest radiograph, is a more reliable method of evaluating the status of bone mineralisation than the femur.

Birth Weight↗
PubMed2004

Distal humerus fractures in elderly patients: results after open reduction and internal fixation.

PROBLEM: Fractures of the distal humerus are difficult to treat. In elderly patients, diminished bone mineral quality and increased trauma-associated joint destruction may make stable joint reconstruction even more problematic. Furthermore, comorbidities and poor tolerance of joint immobilization might be additional factors which influence elbow function negatively. Until now, disagreement has existed on how to treat these fractures in elderly patients. Recommendations range from conservative treatment to primary total elbow replacement. So far, reports in the literature on whether or not open reduction and internal fixation in these patients is justified are very rare. AIM OF THE STUDY: To analyze fracture patterns, surgical approach, complications, and functional results after open reduction and internal fixation in patients of age 60 years and older. PATIENTS AND METHODS: Retrospective clinical study of two university level 1 trauma centers, including 45 patients (median age 73 years; range, 61-92 years) with surgically treated distal humerus fractures. Fracture patterns were recorded according to their AO classification. All patients were treated by open reduction and internal fixation. A clinical and radiological follow-up was obtained after a minimum of 24 months following surgery (median 87 months; range, 24-121 months). Functional results were evaluated according to the Mayo Elbow Score. RESULTS: Fractures with complete joint involvement were seen most often. Taking the fracture type into consideration, functional results deteriorated with degree of joint involvement. Postoperative complication rate was high, predominantly seen as screw loosening and/or implant failure at the lateral column. Neverthless, functional results were preponderating good or excellent. Factors negatively influencing outcome were joint immobilization longer than 14 days and severe joint involvement. DISCUSSION: In elderly patients, distal humerus fractures, which are often considered "osteoporotic fractures," still remain one of the most demanding challenges in trauma surgery. The present study demonstrates that despite diminished bone quality and a high complication rate, open reduction and internal fixation in elderly patients is justified. CONCLUSION: Open reduction and internal fixation of distal humerus fractures in elderly patients should be the main goal, since good elbow function can be achieved in the majority of patients. Elbow immobilization longer than 14 days should be avoided. Stable implant anchorage at the lateral column remains problematic, reflecting a general potential for further implant improvements.

Aged↗
PubMed1995

Combining humerus and femur length for improved ultrasonographic identification of pregnancies at increased risk for trisomy 21.

OBJECTIVE: Our purpose was to evaluate the value of the combination of femur and humerus length measurements in ultrasonographic screening for trisomy 21. STUDY DESIGN: Direct necropsy measurements were analyzed on 703 midgestational fetuses (641 normal, 62 with trisomy 21). The (leg+arm length)/foot length ratio was found to be significantly shortened for fetuses with trisomy 21. On the basis of necropsy data 576 midgestational pregnancies were evaluated ultrasonographically for (femur+humerus length)/foot length ratio to identify fetuses at increased risk for trisomy 21. RESULTS: An ultrasonographic (femur+humerus length)/foot length ratio < or = 1.75 gave a 15.3 odds ratio risk for trisomy 21 in our high-risk population and correctly identified 53% of fetuses with trisomy 21, with a false-positive rate of 7%. In addition, the use of this ratio eliminates the need for gestational age-corrected nomograms and complicated calculations in ultrasonographic screening. CONCLUSION: The (femur+humerus length)/foot length ratio may be an additional effective ultrasonographic marker for identification of fetuses at increased risk for trisomy 21.

Anthropometry↗
PubMed1996

Adaptation to differential loading: comparison of growth-related changes in cross-sectional properties of the human femur and humerus.

Changes in long bone cross-sectional geometry during growth can be influenced by biological and mechanical factors. Here, we assess relationships between cross-sectional geometric properties and length of the human humerus and femur during postnatal growth to test the hypothesis that loading history plays an important role in the development of adult bone morphology. A skeletal sample including 83 paired humeri and femora from individuals between birth and age 30 was examined. Midshaft cross-sectional geometric properties were determined based on computed tomographic scans and the two bones were compared by examining growth trajectories and scaling relationships between the cross-sectional properties and bone length. The growth trajectories for both bones were similar in many respects and showed that increase in length ceased by age 20, whereas increase in cross-sectional properties continued into the third decade of life. When compared to bone length, the cross-sectional geometric properties of the femur and humerus were similar early in postnatal life, but increased at a greater rate in the femur particularly during the first decade of life, leading to divergent adult morphologies. A beam model was developed to predict maximum midshaft strains in each bone as a function of age. The moment acting on the femur was estimated from an analysis of gait in children and the moment acting on the humerus was chosen so that the magnitude of the maximum midshaft strains in the two bones was equivalent in adulthood. With this model, the maximum midshaft strains for the femur were predicted to be higher than for the humerus during the first decade of life. These data support the concept that load history plays an important role in accretion of bone mass during postnatal growth.

Adaptation, Physiological↗
PubMed2002

Design and validation of a surrogate humerus for biomechanical testing.

At present biomechanical testing of fracture plating strategies is conducted using animal or cadaveric whole bone models. This may introduce experimental error into these studies. This communication summarises the design and validation of a novel bone and fibre-reinforced plastic construct conceived to minimise intra-experimental error. A tubular surrogate humerus was produced with dimension and strength matched to that of the human humerus. Bone inserts placed into the wall of the tube allow for the fixation of the plates with bone screws. Three-point bending tests of the flexural rigidity of the surrogate humerus (EI=100.1 (SD 6.0)Nm(2)) showed it to be comparable to the human humerus. Further, pull-out tests of the screws showed that the bone slots adequately mimicked the whole bone scenario. This testing construct will be used for a comparative study of humeral plating techniques.

Animals↗
PubMedDate not supplied

Reduction of triceps muscle force after shortening of the distal humerus: a computational model.

Bone deficiency resulting in shortening of the distal humerus may occur after fractures, treatment of nonunions, or revision of total elbow arthroplasty. A biomechanical model of the triceps muscle and tendon was used to investigate the effect of distal humeral shortening on triceps force production. The analysis indicated that shortening of the distal humerus primarily influences the media head of the triceps, which contributes most to elbow extension strength in extended elbow positions. In a posture of 30 degrees elbow flexion, shortening the distal humerus by 1, 2, and 3 cm reduced the extension strength by 17%, 40%, and 63%, respectively. At 90 degrees of flexion, strength was reduced by 11%, 15%, and 21%, respectively. This result suggests that shortening the humerus by 1 cm may be well tolerated, but shortening by 2 or more cm may cause a significant reduction in triceps force. This would be particularly important in patients requiring terminal extension strength for weight bearing.

Arm↗
PubMedDate not supplied

Extensile approach to the anterolateral surface of the humerus and the radial nerve.

A proposed approach to the anterolateral surface of the humeral shaft that would allow for exploration of the radial nerve was studied in 30 cadaver arms. The incision starts proximally along the posterior border of the deltoid muscle and extends anteriorly and distally over the lateral border of the biceps muscle. A deep dissection is made in the internervous plane between the deltoid and the triceps muscles proximally and between the longitudinally split fibers of the brachialis muscle distally. The approach provides access to the anterolateral surface of the humerus up to the level of the axillary nerve and the posterior circumflex humeral vessels. The insertion of the deltoid muscle into the anterior border of the humerus is preserved and the radial nerve is protected by the triceps muscle proximally and by the retracted lateral portion of the brachialis muscle distally. The entire course of the radial nerve in the arm can be exposed. Proximally, the radial nerve can be exposed by elevating the lateral head of the triceps muscle from the humerus. Distally, the radial nerve can be exposed between the brachioradialis and the brachialis muscles. A plate can be applied on the anterolateral surface of the humerus without having to elevate the firmly attached anterior deltoid insertion.

Arm↗
PubMed1998

Adhesive capsulitis of the shoulder (frozen shoulder) produces bone loss in the affected humerus, but long-term bony recovery is good.

The objective of the study was to assess the short- and long-term effects of adhesive capsulitis (frozen shoulder) on the bone mineral density (BMD) of the affected extremity. BMD and clinical status of 22 patients (group A) with active-phase unilateral adhesive capsulitis and 31 patients (group B) with a previous adhesive capsulitis (average 9 years before the examination) were determined. BMD was measured from the proximal humerus, humeral shaft, radial shaft, ulnar shaft, and distal forearm of both upper extremities using dual-energy X-ray absorptiometry (DXA). In group A, the mean BMD of the affected extremity, as compared with that of the unaffected side, was significantly lower in the proximal humerus (-5.6%; p = 0.001) and humeral shaft (-3.0%; p = 0.008). The radial shaft, ulnar shaft, and distal forearm showed no significant side-to-side differences. In contrast, in group B, the affected-to-unaffected side BMD differences were small and statistically insignificant. Compared with the 31 patients in group B, the relative side-to-side BMD difference of the 22 patients with active-phase disease (group A) was significantly lower in the proximal humerus (-5.6% vs. -1.5%, p = 0.009). In the other sites, groups A and B showed no significant differences. In conclusion, this study indicates that adhesive capsulitis of the shoulder results in significant bone loss in the humerus of the affected extremity, but in the long term, capsulitis-induced bone loss shows good recovery.

Aged↗
PubMed2005

[The arteries of the humerus and their relevance in fracture treatment].

BACKGROUND: The purpose of the current work was to study the arterial blood supply of the humerus to evaluate impairments of the blood supply after humeral fractures and different methods of fracture treatment. METHODS: Arterial blood supply of the humerus was studied by corrosion injection technique in 6 cadaver preparations and is compared with the existing literature. RESULTS: Humeral head arteries originate from the circumflex humeral arteries. The major vessel enters the greater tubercle. Another group of vessels accesses the head from medially. The nutrient artery for the shaft enters into the medial third of the shaft. At the distal humerus there are multiple anastomoses with penetrating branches into both condyles and proximal to the radial, coronoid, and olecranon fossae. CONCLUSIONS: Fragments of a proximal humeral fracture usually have an independent blood supply. The medial vessels to the head gain high importance in fractures of the anatomical neck. The nutrient artery lies regularly medial to the humeral mid-shaft and is at risk at open reduction of this region. The abundant vessels at the entire distal humerus ensure sufficient vascularization of the fragments after fracture.

Arteries↗
PubMed2006

Free fibula flap elbow-joint hemiarthroplasty reconstruction for chronic osteomyelitis of the distal humerus.

The vascularized fibula flap has become a major tool in upper limb reconstruction. Free fibula flap reconstructions of the humeral part of the shoulder and the radial part of the wrist joints are well-documented, but reports of elbow joint reconstruction are rare. The authors report a 53-year-old patient with chronic osteomyelitis of the distal humerus that was unsuccessfully treated by many local surgical debridements and long-term systemic antibiotics. The patient underwent a wide debridement of the distal two-thirds of the humerus, and a spacer was inserted to fill the bony humeral gap. At a second stage, the distal humerus was reconstructed with a free fibula flap that included the proximal fibular head. The fibular shaft was used to bridge the bony gap and the fibular head created an elbow joint with the olecranon process. At an 18-month follow-up after surgery, the patient has stable and sufficient function of his elbow joint with no signs of infection. The free fibula flap has an important role for distal humerus reconstruction, both for bridging the bony gap with a vascularized bone, and for restoring elbow joint function.

Arthroplasty↗
PubMed2005

The causes of pain in benign solitary enchondromas of the proximal humerus.

Patients with benign solitary enchondromas of the proximal humerus frequently present to the diagnosing physician with shoulder pain. Once the lesion is considered benign, emphasis can be placed on identifying the etiology for the pain. We reviewed our experience with these patients to identify the cause of the presenting pain. A retrospective review of clinical records and radiographic studies (radiographs, magnetic resonance images, and bone scans) was done for all patients presenting to an orthopaedic oncology unit with solitary enchondroma of the proximal humerus. Attention was focused on diagnostic evidence of additional disease in the shoulder. Fifty-seven patients (mean age, 53.6 years) met the criteria of the study and were included for evaluation. Of patients presenting with pain, 82% (47 of 57 patients) had findings seen on magnetic resonance imaging scans that correlated with the initial clinical diagnostic impression, suggesting that other disease was present that could explain the pain. Solitary enchondromas of the proximal humerus often are found incidentally during the initial evaluation of patients with shoulder pain. This study showed that additional treatable disease usually is present in patients with enchondromas of the proximal humerus.

Acromioclavicular Joint↗
PubMedDate not supplied

Limb salvage surgery for osteosarcoma of the proximal humerus: outcome in 17 dogs.

OBJECTIVE: To describe function and identify factors that affect outcome in dogs undergoing limb salvage surgery for osteosarcoma (OS) of the proximal humerus. STUDY DESIGN: A retrospective study of dogs in which OS of the proximal humerus was treated with limb salvage surgery. ANIMALS: 17 client-owned dogs. METHODS: Records were analyzed for functional outcome, recurrence, metastasis, and survival. RESULTS: Outcome was good to excellent in 12% of dogs. Recurrence, metastasis, and survival were significantly affected by completeness of surgical margins. Double plating of the distal allograft-host junction significantly reduced frequency of biomechanical failure. CONCLUSIONS: Limb salvage surgery for OS of the proximal humerus did not result in acceptable function and was fraught with postoperative complications. Outcome was significantly affected by completeness of surgical margins. CLINICAL RELEVANCE: Limb salvage surgery for OS of the proximal humerus in dogs cannot be recommended until improvement in functional outcome and reduction in postoperative complications can be achieved. The dependence of outcome on completeness of surgical margins supports aggressive en bloc resection and marking and evaluating surgical margins.

Amputation, Surgical↗
PubMedDate not supplied

Evaluation of a technique for collection of cancellous bone graft from the proximal humerus in horses.

OBJECTIVES: To describe a technique for collecting cancellous bone graft from the proximal humerus in horses. STUDY DESIGN: Prospective evaluation of an experimental bone graft collection technique. ANIMAL POPULATION: Eight horses, 3-15 years, weighing 495-605 kg. METHODS: Horses were anesthetized and positioned in lateral recumbency. The lateral aspect of the proximal humerus was exposed by a 7-10-cm incision extending distally from the greater humeral tubercle, followed by sharp dissection through the omotransversarius muscle and between the infraspinatus and deltoideus muscles. A 12-mm cortical defect was incrementally created in the lateral proximal humerus. Human bone graft harvesting equipment (Acumed, Beaverton, OR) was drilled through this defect to collect a core of cancellous bone. In five horses additional cancellous bone was then collected with conventional instruments. Bone samples were weighed and histologically examined. Horses were monitored and graded for quality of anesthetic recovery, incisional complications, and postoperative lameness. RESULTS: Total mean (+/-SD) surgical time for harvesting bone with the Acumed system and traditional techniques (n=5) was 38+/-6 minutes (range, 32-47 minutes). Mean cancellous bone weight collected with the Acumed system was 3.6+/-0.8 g (range, 2.0-4.6 g), and cancellous bone collected conventionally was 25.6+/-7.5 g (range, 16.8-34.2 g). Minimal incisional complications or postoperative lameness were observed. Mortality was 12.5%; one horse fractured the operated humerus during anesthetic recovery. CONCLUSION: The Acumed system provided limited cancellous bone when used with the technique described. However, the quantity of cancellous bone collected with traditional harvesting instruments was comparable to other sites used in horses. The procedure was associated with minimal postoperative incisional complications or lameness, but because one horse suffered a catastrophic humeral fracture further research is required to assess the effects of this procedure on humeral breaking strength. CLINICAL RELEVANCE: Based on the risk of catastrophic fracture, this technique cannot be recommended for use in clinical cases, especially if an unassisted recovery from general anesthesia is planned.

Animals↗
PubMed1992

Morphological effects of mechanical forces on the human humerus.

Various mechanical forces produce a variable stimulus intensity on bone and have different effects on its growth and development. The aim of this project was to study the effects of a variety of mechanical forces on human humerus morphology. This was investigated by measuring the cortical thickness (cm) and diameter (cm) of the humerus at its proximal, middle and distal thirds from radiographs. The humerus of each of 46 men (five controls, six swimmers, eight gymnasts, seven javelin throwers, nine discus throwers and 11 weightlifters) was radiographed on both right and left sides. The humerus size variation among the participants, in order of increasing size, was found to be as follows: gymnasts, controls, swimmers, javelin throwers, weightlifters and discus throwers respectively. The humeral cortex was largest in the weightlifters, being significantly (P less than 0.05) thicker at distal, medial and proximal sites. The proximal and distal humeral sites in javelin and discus throwers were significantly thicker than those of the control subjects. From the results, static load would seem to provide a higher stimulus to bone than dynamic loading.

Biomechanical Phenomena↗
PubMed2005

Distribution of small proteoglycans and glycosaminoglycans in humerus-related articular cartilage of chickens.

The expression of components present in the cartilaginous extracellular matrix is related to development, gender, and genotype, as well as to the biomechanical properties of each type of cartilage. In the present study, we analyzed small proteoglycans and glycosaminoglycans present in different cartilages of the chicken wing after extraction with guanidine hydrochloride or papain. Quantitative analysis of glycosaminoglycans showed a larger amount in humeral cartilage (around 200 mg/g tissue) than in articular cartilage of the radius and ulna, with 138 and 80 mg/g tissue, respectively. Non-collagenous proteins isolated were predominantly from cartilage in the proximal regions of the humerus and radius. D4 fractions obtained by ultracentrifugation were separated by DEAE-Sephacel and Octyl-Sepharose chromatography and analyzed by SDS-PAGE. Two bands of 57 and 70-90 kDa were observed for all samples treated with beta-mercaptoethanol. Immunoblotting of these proteins was positive for the small proteoglycans fibromodulin and decorin, respectively. Apparently, the 57-kDa protein is present in macromolecular complexes of 160 and 200 kDa. Chondroitin sulfate was detected in all regions. HPLC analysis of the products formed by chondroitinase AC and ABC digestion mainly revealed beta-D-glucuronic acid and N-acetyl beta-D-galactosamine residues. The 4-sulfation/6-sulfation ratio was close to 3, except for the proximal cartilage of the radius (2.5). These results suggest functional differences between the scapula-humerus, humerus-ulna, and humerus-radius joints of the chicken wing. This study contributes to the understanding of the physiology of cartilage and joints of birds under different types of mechanical stress.

Animals↗
PubMed1999

Complications and functional outcomes of reconstruction with an osteoarticular allograft after intra-articular resection of the proximal aspect of the humerus.

BACKGROUND: The purpose of this study was to evaluate the functional outcome and the complications of reconstruction with an osteoarticular allograft in patients who had had intra-articular resection of the proximal aspect of the humerus. METHODS: Sixteen patients who had had intra-articular resection and reconstruction of the proximal aspect of the humerus for the treatment of a tumor between 1986 and 1996 were evaluated. The length of the resected part of the humerus ranged from eight to 27.5 centimeters. The resections were classified as either S34A or S345A resections of the shoulder girdle on the basis of the Musculoskeletal Tumor Society classification system. Reconstruction was performed with use of a nonirradiated, frozen osteoarticular allograft with intact capsular and rotator cuff attachments. Dual orthogonal dynamic compression plates were used for internal fixation of the allograft to the host bone. The oncological parameters that were evaluated included survival of the patient, local recurrence, and metastasis. The radiographic parameters included time to union, stability of the joint, fracture of the allograft, and fragmentation of the epiphysis of the allograft (subchondral collapse). Survival of the graft was assessed with Kaplan-Meier survival analysis. The modified Musculoskeletal Tumor Society evaluation system was used to assess functional outcome. RESULTS: At a median of forty-seven months (range, fourteen to 130 months) after the operation, fourteen of the patients in the study group were free of disease and two had died of disease. No patient had local recurrence or nonunion. Late complications included four fractures of the allograft and one infection of the graft. A Kaplan-Meier survival curve demonstrated a 68 percent rate of survival of the allograft at five years. Instability of the glenohumeral joint in the form of ptosis and anterior subluxation was noted in three patients, and dislocation of the glenohumeral joint was seen in eight patients. On the basis of the modified Musculoskeletal Tumor Society functional evaluation, the mean score at the most recent follow-up evaluation (at a mean of thirty-four months) was 70 percent. This score was lower than the mean score of 81 percent at a mean of fourteen months. All patients had normal manual dexterity and had mild or no pain at the most recent follow-up evaluation. However, all had restriction of recreational activities or partial disability in addition to limitations with regard to placement of the hand and the ability to lift. CONCLUSIONS: Reconstruction of the proximal aspect of the humerus with an osteoarticular allograft is an option that provides good relief of pain and preserves manual dexterity. However, in our study, function was limited by impairment of elevation of the shoulder and hand as well as by decreased strength of the shoulder. There was an extremely high rate of complications, including joint instability, fracture of the allograft, and infection of the allograft. We no longer routinely perform this reconstruction at our institution.

Adolescent↗
PubMed2005

Thermal tissue damage caused by ultrasonic cement removal from the humerus.

BACKGROUND: Ultrasound devices can selectively remove cement during revision arthroplasty. These instruments initially were designed for the hip and knee but also have been applied to the upper extremity. We describe a patient in whom a radial nerve palsy and a pathologic humeral fracture developed after ultrasonic cement removal was performed because of an infection at the site of a total elbow arthroplasty. Biopsies of the humerus, the triceps muscle, and the radial nerve showed widespread necrosis consistent with thermal injury. METHODS: A study involving six human cadaveric specimens was conducted to measure temperature elevations in bone and adjacent soft tissue during cement removal with use of an ultrasound device with and without irrigation. RESULTS: While temperature increased only minimally during cement polymerization, ultrasonic melting and removal of cement with use of constant energy delivery led to markedly elevated temperatures in the humeral cortex, the triceps muscle, and the radial nerve. These temperatures were above the known thresholds for thermal injury and necrosis. Subsequently, strategies designed to allow for safe ultrasonic cement removal from the humerus were applied, including intermittent delivery of energy and the use of cold irrigation between probe passes. These strategies resulted in markedly lower maximum temperatures in all tissues tested. CONCLUSIONS: Temperatures in the humerus, triceps, and, most importantly, the radial nerve can reach potentially dangerous levels when ultrasound technology is used to remove cement from the humerus. We suggest intermittent cold irrigation of the humeral canal, no tourniquet use, education of surgeons with regard to proper techniques designed to limit heat generation, and consideration of exposure and protection of the radial nerve when ultrasound devices are used.

Aged↗