Laminar airflow versus turbulent airflow in simulated total hip arthroplasty: measurements of colony-forming units, particles, and energy consumption.

BACKGROUND: The optimal type of ventilation in operating theatres for joint arthroplasty has been debated for decades. Recently, the World Health Organization changed its recommendations based on articles that have since been criticized. The economic and environmental impact of ventilation is also currently an important research topic but has not been well investigated. AIM: To compare how large, high-volume, laminar airflow (LAF) and turbulent airflow (TAF) ventilation systems perform during standardized simulated total hip arthroplasty (THA), as they pertain to colony-forming units (cfu), particle counts, and energy consumption. METHODS: Two identical operating theatres were used to perform simulated THA. The only difference was that one was equipped with LAF and the other with TAF. Cfu and particles were collected from key points in the operating theatre, and energy was measured for each simulation. Thirty-two simulations were done in total. FINDINGS: LAF had significantly reduced cfu and particle count when compared with TAF, at both 100% and 50% air influx. Furthermore, it was shown that lowering the air influx by 50% in LAF did not significantly affect cfu or particles, although reducing the fresh air influx from 100% to 50% significantly lowered the energy consumption. Most simulations in TAF did not meet the cleanroom requirements. CONCLUSION: Cfu were significantly lower in LAF at both 100% and 50% air influx. It is possible to reduce fresh air influx in LAF operating theatres by 50%, significantly reducing energy consumption, while still maintaining cfu and particle counts below the ISO classification threshold required for THA surgery.

Changes in clavicle length in acute fractures within 3 weeks: a prospective ultrasonographic study of 59 patients.

BACKGROUND: Within traumatology a common indication for acute surgery of fractured clavicles is bone shortening over 2 cm. This indication is among but a few indications; which are recommended to be treated operatively within the very first weeks after a fracture. Theoretically clavicle fractures could become less shortened over time due to decreasing muscle pull. If this reduced shortening does indeed happen, some patients with initial bone shortening over 2 cm could perhaps be treated conservatively? However, it is unknown what happens to the length of the clavicle within the first weeks after a fracture. The aim of this study was to investigate if the length of the fresh fractured clavicles changes within the first three weeks. METHODS: Rested length measurements using navigation ultrasound were done on 59 patients with a fractured clavicle. Measurements were performed within the first three weeks after a lateral or mid-clavicular fracture. The inclusion period was from March 2014 to February 2016. Median age was 40 years and age range was 18-81 years. The data was analyzed using mixed linear models. RESULTS: The clavicle length showed no change within the first three weeks after fracture (p = 0.24). CONCLUSION: Fractured clavicles retain their length for the first three weeks.

Bone shortening of clavicular fractures: comparison of measurement methods.

BACKGROUND: The indication for operative treatment of clavicular fractures with bone shortening over 2 cm is much debated. Correct measurement of clavicular length is essential, and reliable measures of clavicular length are therefore highly requested by clinical decision-makers. The aim of this study was to investigate if three commonly scientifically used measurement methods were interchangeable to each other. METHODS: A retrospective study using radiographs collected as part of a previous study on clavicular fractures. Two independent raters measured clavicle shortening on 60 patients using conventional radiographs on two separate sessions. The two measurement methods described by Hill et al. and Silva et al. were used on unilateral pictures. Side difference measurements according to Lazarides et al. were made on panoramic radiographs. The measurements were analyzed using intraclass correlation, Weir's protocol for Standard error of measurement (SEM) and minimal detectable change (MDC), and Bland-Altman plots. RESULTS: None of the methods were directly interchangeable. The side difference method by Lazarides et al. was the most reliable of the three methods, but had a high proportion of post-fracture bone lengthening that indicated methodological problems. The Hill et al. and Silva et al. methods had high minimal detectable change, making their use unreliable. CONCLUSION: As all three measurement methods had either reliability or methodological issues, we found it likely that differences in measurement methods have caused the differences in clavicular length observed in scientific studies.

Work related shoulder disorders: quantitative exposure-response relations with reference to arm posture.

AIMS: To determine quantitative exposure-response relations between work with highly elevated arms and supraspinatus tendinitis, shoulder pain with disability, and shoulder pain without disability. METHODS: A cross sectional study was conducted in a historical cohort of 1886 males from three occupational groups. Exposure measurements were performed for four consecutive working days in a random sample of 72 currently employed subjects. Individual work histories were obtained by questionnaire and register data. Health status was ascertained by physical examination blinded towards exposure and symptoms. Data were analysed by generalised estimating equation and multiple logistic regression with adjustment for potential confounders. RESULTS: For current upper arm elevation above 90 degrees, a duration increment of 1% of the daily working hours was associated with odds ratios of 1.23 (95% CI 1.10 to 1.39) for supraspinatus tendinitis, 1.16 (95% CI 1.08 to 1.24) for shoulder pain with disability, and 1.08 (95% CI 1.04 to 1.13) for shoulder pain without disability. The outcomes were not related to duration of employment in one of the three trades. CONCLUSIONS: Quantitative exposure-response relations were established between current work with highly elevated arms and clinically verified shoulder disorders. Substantial long term cumulative effects were not shown. A potential for primary prevention was revealed.

A three-dimensional finite element model from computed tomography data: a semi-automated method.

Three-dimensional finite element analysis is one of the best ways to assess stress and strain distributions in complex bone structures. However, accuracy in the results may be achieved only when accurate input information is given. A semi-automated method to generate a finite element (FE) model using data retrieved from computed tomography (CT) was developed. Due to its complex and irregular shape, the glenoid part of a left embalmed scapula bone was chosen as working material. CT data were retrieved using a standard clinical CT scanner (Siemens Somatom Plus 2, Siemens AG, Germany). This was done to produce a method that could later be utilized to generate a patient-specific FE model. Different methods of converting Hounsfield unit (HU) values to apparent densities and subsequently to Young's moduli were tested. All the models obtained were loaded using three-dimensional loading conditions taken from literature, corresponding to an arm abduction of 90 degrees. Additional models with different amounts of elements were generated to verify convergence. Direct comparison between the models showed that the best method to convert HU values directly to apparent densities was to use different equations for cancellous and cortical bone. In this study, a reliable method of determining both geometrical data and bone properties from patient CT scans for the semi-automated generation of an FE model is presented.

Late results of total shoulder replacement in patients with rheumatoid arthritis.

Rheumatoid arthritis of the shoulder is a progressive and destructive joint disease, and similar to arthritis in other joints, progression of the disease is unpredictable and may stop at any stage of involvement. Between 1983 and 1996, more than 500 shoulder prostheses were implanted in patients at the authors' institution. Total shoulder replacement yields satisfactory short and long term results even in patients with severely destructed joints. Pain relief is reliable and significant as reported in short and long term studies. In most patients the functional result is good or acceptable. Although range of motion is only slightly increased, a satisfactory overall range of motion is achieved by most patients because of the unaffected scapulothoracic motion. However, deteriorating results, emphasizing the complexity of shoulder arthroplasty, were seen with increasing observation time in patients with rheumatoid arthritis. Proximal migration of the humeral prosthesis attributable to rotator cuff failure, with secondary eccentric glenoid loading and progressive loosening, is latent in patients with chronic progressive rheumatoid disease and was by far the most common complication (42%) in the present series.

Glenoid bone architecture.

This article describes regional variations in trabecular bone architecture in terms of density and orientation within six glenoid specimens. The mean donor age was 56 years and ranged from 31 to 72 years. An automated imaging technique based on 3-dimensional serial sectioning was used for the direct examination of the glenoid cancellous bone structures. Subchondral plate thickness was on average 1.9 mm and ranged from 1.2 mm to 2.9 mm. The volume fraction of trabecular bone varied from 11% to 45% with peak values at the posterior glenoid vault. On graphic 3-dimensional reconstructions, the glenoid appeared as platelike trabeculae, radially oriented perpendicular to the subchondral plate and interconnected by thin rods. These views also displayed regional variations throughout the glenoid, reflecting differences in the macroscopic appearance. Quantitative structural analysis revealed different degrees of anisotropy at the glenoid cancellous region, predominantly transverse isotropy. Resemblance to direct weight-bearing cancellous bone such as the proximal tibia was evident.

Bone strength and material properties of the glenoid.

The quality of the glenoid bone is important to a successful total shoulder replacement. Finite element models have been used to model the response of the glenoid bone to an implanted prosthesis. Because very little is known about the bone strength and the material properties at the glenoid, these models were all based on assumptions that the material properties of the glenoid were similar to those of the tibial plateau. The osteopenetrometer was used to assess the topographic strength distribution at the glenoid. Strength at the proximal subchondral level of the glenoid averaged 66.9 MPa. Higher peak values were measured posteriorly, superiorly, and anteriorly to the area of maximum concavity of the glenoid joint surface known as the bare area. One millimeter underneath the subchondral plate, average strength decreased by 25%, and at the 2 mm level strength decreased by 70%. The contribution of the cortical bone to the total glenoid strength was assessed by compression tests of pristine and cancellous-free glenoid specimens. Strength decreased by an average of 31% after the cancellous bone was removed. The material properties of the glenoid cancellous bone were determined by axial compression tests of bone specimens harvested from the central part of the glenoid subchondral area. The elastic modulus varied from approximately 100 MPa at the glenoid bare area to 400 MPa at the superior part of the glenoid. With the elastic constants used a predictor of the mechanical anisotropy, the average anisotropy ratio was 5.2, indicating strong anisotropy. The apparent density was an average 0.35 gr. cm-3, and the Poisson ratio averaged 0.263. According to our findings the anisotropy of the glenoid cancellous bone, details concerning the strength distribution, and the load-bearing function of the cortical shell should be considered in future finite element models of the glenoid.

Magnetic resonance imaging evaluation of capsulolabral tears after traumatic primary anterior shoulder dislocation. A prospective comparison with arthroscopy of 25 cases.

The purpose of our study was to evaluate the use of static magnetic resonance imaging (MRI) as a preoperative diagnostic tool in young patients with a traumatic primary anterior shoulder dislocation. Twenty-five patients who had acute primary traumatic anterior shoulder dislocation were examined with MRI and arthroscopy. The patients (18 male and 7 female) were between 16 and 39 years old (mean age, 27 years). They had no previous shoulder dislocations. The dislocations were confirmed radiographically. Examination with MRI and arthroscopy was performed within 10 days after the trauma. The MRI evaluation was performed before the arthroscopic examination, and the images were interpreted by an experienced magnetic resonance radiologist. No information from the MRI examination was available to the orthopedic surgeons before arthroscopy. The standard of reference for comparison was arthroscopy. Subacute MRI evaluation identified 15 labral tears, 12 Hill-Sachs lesions, 1 total rotator cuff lesion, 1 partial joint side rotator cuff lesion, and 1 partial rupture of the biceps tendon. Arthroscopic examination revealed 22 labral tears, 15 Hill-Sachs lesions, 1 total rotator cuff lesion, 1 partial joint side rotator cuff tear, 1 partial rupture of the biceps tendon, and 1 osseous Bankart lesion. Anterior capsulolabral tears and Hill-Sachs lesions appeared with a high incidence after acute anterior primary shoulder dislocation. Conventional MRI was only moderately reliable in the preoperative evaluation of labral tears and Hill-Sachs lesions, and it failed to give an accurate, differentiated preoperative diagnosis of the capsulolabral lesions.

Intraarticular findings in the chronically painful shoulder. A study of 32 posttraumatic cases.

32 consecutive patients suffering from chronic shoulder pain for more than 6 months after a single, nondislocating shoulder trauma were examined clinically and by special radiographs, dynamic sonography, MRI and arthroscopy. Typical complaints were pain during loading, especially during over the head activities. Symptoms of a "dead arm" and instability were also present. Patients with previous dislocations, traumas or radiographic signs of degenerative shoulder lesions were excluded. The patients had a decreased active range of motion and positive signs of apprehension and impingement, but only 4 had clinical signs of shoulder instability. Diagnostic evaluation identified labral tears, partial and total rotator cuff lesions with subacromial impingement and tendinitis of the biceps tendon. Surgery was performed in 24 patients, using capsulolabral and rotator cuff reconstruction, arthroscopic labral resection and open subacromial decompression. In conclusion, patients with chronic posttraumatic shoulder pain have intraarticular injuries, especially tears of the glenoid labrum. History, clinical findings, radiography and sonography are seldom diagnostic. MRI is valuable, particularly for identification of labral pathology, but arthroscopy appears necessary for a preoperative assessment.

Three-dimensional reconstruction of entire vertebral bodies.

This paper describes a technique for 3-D reconstruction of large cancellous bone regions. The output is a 3-D array describing the original cancellous bone region, and the output can be used for any kind of measurement of the bone architecture. The technique was developed as a tool for researchers conducting experimental and clinical studies related to cancellous bone architecture and, ultimately, to cancellous bone quality. A set of new and unbiased methods for quantification of cancellous bone has been a stimulus for the development of the technique, as the quantification methods rely on 3-D information. The technique is based on automated serial sectioning, and all steps from specimen preparation to image segmentation are described in detail. Examples of 3-D reconstructed vertebral bodies are given. By use of the described technique, between 300 and 600 sections can be made and registered per hour, which means that an average vertebral body can be reconstructed in about 2 h. Compared to previous implementations of the general principle of serial sectioning, this is a significant improvement both in resolution and in time efficiency.

Shoulder arthroplasty in complex acute and chronic proximal humeral fractures.

From 1983 to 1988, 42 shoulder arthroplasties were performed on comminuted acute or chronic proximal humeral fractures. Patients were categorized according to the post-fracture operative delay; there were 15 four-part fractures, with median post-fracture delay of 13 days (range: 7 to 21), and 27 chronic fractures, including 11 four-part fractures, 9 three-part fractures, and 7 two-part fractures, with median post-fracture delay of 14 months (range: 4 to 72). Follow up was approximately 2 years in both groups (range: 1 to 5). All patients were evaluated according to a modified Neer score-system and classified into four groups. Pain relief was satisfactory in the acute group, but was unpredictable in the chronic group. The results in the acute group were significantly superior (P less than .05). In the acute group, 3 (20%) patients had an excellent result and 6 patients (40%) had a good result, compared to a good result obtained by 6 patients (22%) in the chronic group. Two patients (13%) in the acute group and 11 patients (40%) in the chronic group had a poor result. There were no statistical differences between two-part, three-part, or four-part fractures in the chronic group. Five cases of persistent instability were seen in shoulders formerly treated with osteosynthesis (one acute and four chronic cases). Two of these cases developed an infection. Good results can be expected after prosthetic replacement in acute proximal humeral fractures. Failed primary treatment reduces the possibility of a good result with revision arthroplasty.

Instability of the hindfoot after lesion of the lateral ankle ligaments: investigations of the anterior drawer and adduction maneuvers in autopsy specimens.

The mobility patterns in the tibiotalocalcaneal joint complex with a solitary lesion of the anterior talofibular ligament (ATL) and a combined lesion of the ATL and calcaneofibular ligament (CFL) were studied in 22 human lower-extremity autopsy specimens mounted in a kinesiologic testing device. A solitary lesion of the ATL increased the anteroposterior (AP) laxity in the ankle joint in the entire range of flexion, with a maximum median of 3.1 mm in neutral flexion. Further cutting of the CFL increased AP laxity most obviously in dorsiflexion. A solitary lesion of the ATL resulted in a minor instability in adduction, whereas further lesion to the CFL increased adduction in the entire range of flexion, with a maximum median of 14.2 degrees in dorsiflexion. The anterior drawer maneuver can reveal a combined lesion of the ATL and CFL if performed with the tibiotalocalcaneal joint complex in dorsiflexion. Significant clinical instability in adduction will only take place when a combined lesion of the ATL and CFL is present.

Lateral hindfoot instability treated with the Evans tenodesis: a biomechanical analysis.

The stabilizing effect of the Evans tenodesis on movements in the tibiotalocalcaneal joint complex was studied in 10 amputation specimens, using a kinesiologic testing device. The tenodesis was tested following solitary lesion of the anterior talofibular ligament and after combined lesions of the anterior talofibular and calcaneofibular ligaments. All tenodeses were performed with the joint complex in the neutral position. Regardless of the extent of ligamentous damage, the tenodesis frequently restricted adduction and internal rotation to a level below that recorded at intact ligaments. Instability in external rotation in the joint complex and anteroposterior laxity of the talus were never completely reconstructed, regardless of what degree of flexion in the joint complex the tenodeses were tested. The study demonstrates that, if performed with the tibiotalocalcaneal joint complex in the neutral position, the Evans tenodesis cannot reconstruct normal hindfoot kinematics, irrespective of the extent of ligamentous damage. However, severe instability in adduction and internal rotation, both part of clinical supination, were effectively prevented by the tenodesis.

Three-axial strain controlled testing applied to bone specimens from the proximal tibial epiphysis.

Reproducibility of the determination of Young's modulus and energy absorption along the three axes of trabecular bone cubes was analysed by non-destructive compression to 0.5% strain using different testing protocols. These protocols included testing with and without pre-conditioning to a viscoelastic steady state, and different orders of test directions. Reproducibility of conditioned tests was generally better than that of non-conditioned tests. No major effect of changing the order of the test direction was found. Three-axial conditioned testing of cubes from the proximal tibial epiphysis of five humans revealed a global transverse isotrophy while most cubes showed orthotropy. The ratio between stiffness along the long axis of the tibia and the stiffness in the transverse plane was 3.7 +/- 0.4 (mean +/- 2 SE). The corresponding ratios for elastic energy storage and viscoelastic energy dissipation were 2.5 +/- 0.2. There was no difference between the relative energy loss during a testing cycle (loss tangent) in the three axes.

Retroversion of the humeral prosthesis in shoulder arthroplasty. Measurements of angle from standard radiographs.

A method for assessing the retroversion angle of the humeral prosthesis in total shoulder arthroplasty is presented. The method is accurate and simple, requiring only an anteroposterior radiograph and a conversion table.

Chondromalacia induced by patellar subluxation in the rabbit.

A unilateral patellar malalignment was induced in 20 young and 20 mature rabbits by lateral displacement of the tibial tuberosity, the other knee serving as osteotomized in situ control. At 6 weeks, all the knees appeared macroscopically normal, but histologically definite cartilage degeneration was found on the experimental side. At 3 months, macroscopic changes occurred in 5 of 10 mature rabbits, and histologic cartilage degeneration was found in all the experimental knees, most pronounced in mature animals, and particularly in joint facets submitted to high pressure. This experimental model produces changes resembling chondromalacia patellae and early arthrotic changes suggesting the importance of malalignment in the development of patellofemoral cartilage degeneration.

Arthroscopy in diagnosis and treatment of hip disorders.

Fourteen hip arthroscopies between January 1985 and May 1988 were reviewed. Included were ten women and four men with an age ranging from 12 to 76 years. Indications were avascular necrosis; loose bodies; osteoarthrosis, arthritis, or pain; and snapping hip. The diagnosis was verified in five cases, including arthroscopic removal of a loose body in one and resection of a plica bridging the space between the femoral head and acetabular roof in two patients. The diagnosis was rejected in three cases. In five cases, no pathologic changes were found. One arthroscopy was inconclusive because of a narrow field of vision in a dysplastic hip. No serious complications occurred. Hip arthroscopy is useful in diagnostics and surgical treatment of selected hip disorders. The rehabilitation time is short. Hip arthroscopy is, however, a technically demanding procedure.

Heterotopic bone formation following total shoulder arthroplasty.

The incidence and location of heterotopic bone formation following total shoulder arthroplasty were evaluated in 58 Neer Mark-II total shoulder replacements. One year after surgery, 45% had developed some ectopic ossification. In six shoulders (10%) the ossifications roentgenographically bridged the glenohumeral and/or the glenoacromial space. There was no correlation between shoulder pain and the development of ossification. Shoulders with grade III heterotopic bone formation had a limited range of active elevation compared with shoulders without or with only a milder lesion. Men and patients with osteoarthritis of the shoulder joint were significantly disposed to the development of heterotopic bone. Heterotopic bone formation following total shoulder arthroplasty is frequent, but disabling heterotopic ossifications seem to be rare.