[Epicondylosis : Open surgical procedure-when and how for lateral and medial epicondylitis?] / Epikondylopathie des Ellenbogens : Offenes operatives Vorgehen ­ wann, wie für lateral und medial?

BACKGROUND: Epicondylosis of the elbow are common pathologies, with a higher incidence for radial epicondylosis. Approximately 90% are self-limiting under conservative treatment. TREATMENT: Multiple surgical procedures exist for the treatment of refractory cases. Arthroscopic treatment has been described for both radial and medial pathologies. Open and arthroscopic procedures show equivalent results in the surgical treatment of radial epicondylosis. This paper describes the most common open surgical procedures for the treatment of radial epicondylosis. Furthermore, the pros and cons of the arthroscopic versus the open approach are discussed, and the indications for an open surgical procedure for radial pathologies are highlighted. The authors believe that the open technique represents the standard treatment in the surgical treatment of ulnar epicondylosis. LIMITATIONS: Arthroscopic procedures have been described, but studies comparing the clinical outcome versus open surgical treatment are lacking. The anatomic proximity of the flexor origin to the ulnar nerve with the risk of iatrogenic damage is another limiting factor. In addition, concomitant pathologies on the ulnar side can better be ruled out preoperatively, so that arthroscopy has a rather low significance in the treatment of ulnar epicondylosis.

Lateral Ulnar Collateral Ligament Reconstruction for Posterolateral Rotatory Instability After Failed Common Extensor Origin Release: Outcomes at Minimum 2-Year Follow-up.

BACKGROUND: In patients with chronic lateral epicondylitis who have failed nonoperative treatment, open or percutaneous release of the common extensor origin (CEO) without subsequent reconstruction tends to result in good clinical outcomes. However, surgery can lead to iatrogenic injuries of the lateral collateral ligamentous complex, causing posterolateral rotatory instability (PLRI). PURPOSE: To determine the clinical outcomes of lateral ulnar collateral ligament (LUCL) reconstruction using a triceps tendon graft after failed open CEO surgery. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A total of 103, patients underwent revision surgery at a single institution because of PLRI after failed open release of the CEO (Hohmann procedure) between January 2007 and October 2016. The primary surgery had been performed at other institutions in all cases. Of these patients, 72 were available for follow-up (49 by clinical examination, 23 by telephone interview). Standardized clinical examination; Mayo Elbow Performance Score (MEPS); 11-item version of the Disabilities of the Arm, Shoulder and Hand Score (QuickDASH); subjective elbow value (SEV); and patient satisfaction were assessed at least 2 years after LUCL reconstruction. RESULTS: The mean age of patients in the study was 46.9 years (range, 21-74 years), and the mean follow-up was 2.8 years after revision surgery. The mean MEPS was 78.9, and the mean QuickDASH score reached 20.4. The mean SEV was 78.6%, and 75% of the patients rated the surgery as good to excellent. Complications were detected in 14% of the patients, and 9 needed revision surgery, primarily owing to graft failure with recurrent instability (n = 5). CONCLUSION: LUCL reconstruction in patients with PLRI after release of the CEO can restore elbow stability and achieve high patient satisfaction. However, outcome scores and revision rates in this cohort were inferior to published outcomes of primary LUCL reconstruction for treatment of noniatrogenic or traumatic PLRI.

Translation of the Mayo Elbow Performance Score (MEPS) into German (MEPS-G). / Die Übertragung des Mayo Elbow Performance Score (MEPS) ins Deutsche (MEPS-G).

BACKGROUND: The Mayo Elbow Performance Score is a clinical assessment to rate the performance of the elbow from a medical and/or therapeutic perspective. It is simple and efficient to operate and therefore frequently used in research as well as in clinics. However, an adequate translation of the MEPS into the German language and a verification of the quality criteria for the use in the German health system are currently lacking. GOAL OF THE STUDY: The aim of this study is to translate the MEPS and to review the applicability of the German version (MEPS-G) in Germany. MATERIALS AND METHODS: The translation was undertaken on the basis of a guideline for cultural adaptation. Two independent translations were created, combined and translated back into English by two native speakers. The back translations were reviewed and the German version was amended accordingly. The suitability of the final questionnaire was verified in a pretest with 73 participants. RESULTS: The MEPS was converted into the German version MEPS-G and was tested. Apart from minor adjustments, the questionnaire was translated into German without difficulty. The time to complete the assessment was on average 2.5 min (± 1.6). CONCLUSION: First analyses of the psychometric properties of the German MEPS showed identical values as the English version. The detailed quality criteria will be reviewed in a subsequent study.

The influence of three-dimensional planning on decision-making in total shoulder arthroplasty.

BACKGROUND: Long-term results and complication rates in shoulder arthroplasty are related to implant positioning. Current literature reports increased precision in glenoid component positioning using 3-dimensional (3D) computed tomography (CT) planning tools. This study evaluated the accuracy of glenoid version and inclination measurements using 2D CT scans compared with a validated 3D software program and its influence on decision making on implant selection. METHODS: Preoperative CT scans were obtained from 50 patients undergoing total shoulder arthroplasty. Glenoid version and inclination measurements were performed in random order by 3 independent qualified orthopedic surgeons on reformatted 2D CT scans. Indication for anatomic or reverse shoulder arthroplasty was based on glenoid deformity and on rotator cuff conditions. Results were compared with those from a validated 3D computer software program, and the final decision was made according to the 3D planning. RESULTS: Mean preoperative glenoid retroversion on reformatted 2D CT scans was 11.9° ± 9.6° and mean superior inclination was 10.7° ± 8.6°. When the 3D software was used, glenoid retroversion averaged 15.1° ± 10.6° and superior inclination averaged 8.9° ± 9.9°. The 2D CT demonstrated good interobserver and intraobserver reliability for glenoid version and inclination. Decision on the choice of implant was adjusted in 7 patients after the 3D planning. CONCLUSIONS: Our findings show that measurements of glenoid version and inclination on reformatted 2D CT scans are less accurate compared with 3D measurements. A preoperative 3D planning software allows for improvement of virtual glenoid positioning and influences the decision making process.

Long-term analysis of revision reverse shoulder arthroplasty using cemented long stems.

BACKGROUND: Revision of failed shoulder arthroplasty is often associated with poor results and a high rate of complications. Significant humeral bone loss after removal of long stems poses a considerable surgical challenge. Therefore, the aim of our study was the evaluation of the clinical and radiologic outcome of cemented long-stem humeral components in revision reverse shoulder arthroplasty with a minimum 5 years' follow-up. METHODS: Between June 2001 and June 2009, revision reverse shoulder arthroplasty using long-stem cemented humeral components was performed in 124 patients. Mean age at time of surgery was 69.6 years (range, 42-87 years). Complete clinical and radiographic data were available in 50 patients at a mean of 7 years (range, 5-11.6 years). Postoperative radiographs were evaluated for radiolucent lines, implant migration, fracture, and glenoid notching. RESULTS: The mean Constant score improved from 11.1 points (range, 0-27 points) to 39.5 points (range, 14-73 points) at the latest follow-up. Progressive humeral radiolucency was present in 24 patients, including 6 patients demonstrating complete loosening or progressive distal migration of the humeral stem. We noted an overall of 12 additional complications in 8 patients, necessitating revision surgery in 16. CONCLUSION: The use of long-stem humeral components is a beneficial treatment in revision reverse shoulder arthroplasty. Nevertheless, the high percentage of patients with humeral loosening is concerning. Modular cementless revision stems that are adapted to the distal humeral medullary canal and additional distal screw and cable fixation might enhance durable distal fixation in case of advanced bone loss.

Is the distal radioulnar variance useful for identification of radial head prosthesis overlengthening? A cadaver study.

BACKGROUND: Overlengthening by radial head prosthetic replacement leads to insufficient functionality and increased capitellar wear. It has been shown that in monopolar prostheses, the radial overlengthening by an overstuffed prosthesis leads to significant differences in the distal radioulnar variance at the wrist. This study evaluated ipsilateral ulnar variance as a predictor for overlengthening after implantation of a multipolar prosthesis. METHODS: The radial heads of seven fresh frozen upper extremities were resected and a multipolar radial head prosthesis was implanted. Thereafter, the native radioulnar variance at the wrist was documented via fluoroscopy. The alignment of the distal radioulnar joint in neutral, pronated and supinated rotational positions of the forearm was recorded fluoroscopically, and digital image analysis was performed regarding radioulnar shifting. RESULTS: Statistical analysis of the difference between native height and the manipulated states did not show consistent significant differences with stepwise overlengthening of +1.5, +3, +4.5 and +6 mm and with respect to rotational position of the forearm (p > 0.05). Interclass correlation coefficients showed excellent interobserver reliability (ICC 96%), as did tests for intraobserver reliability (ICC 98-99%). CONCLUSIONS: No consistent influence of overlengthening on the alignment of the radius and ulna at the distal radioulnar joint was found after sequential overlengthening with a multipolar prosthesis. Maybe the ligamentous structures of the forearm prevent significant longitudinal dislocation of the radius, as the multipolar prosthesis gives way by at the radiocapitellar joint. According to the data of the present study, the ipsilateral wrist is not useful in diagnosing overlengthening of the radial column in multipolar prosthetic replacement of the radial head-in contrast to the reported results with monopolar prostheses.

Shoulder arthroplasty in Germany: 2005-2012.

INTRODUCTION: The field of shoulder endoprothetics has undergone a rapid development in the last years. The purpose of the study was to provide an overview of the development of shoulder arthroplasties in Germany from 2005 until 2012. This study hypothesized that the surgical procedures of the shoulder joint is still increasing and have not reached a plateau until 2012. METHODS: Data of the German federal statistical office from 2005 until 2012 were analyzed to quantify hemiarthroplasty, anatomic total shoulder and reversed total shoulder arthroplasty rates depending on age, gender and main coded indications. Procedure codes and diagnosis were analyzed for each year. Comparative analyses were used to visualize the difference between the types of shoulder endoprostheses. RESULTS: A total number of 139.272 shoulder arthroplasties were performed between 2005 and 2012. Total should arthroplasties have increased continuously until 2009. In 2009 more total shoulder arthroplasties have been performed than hemiprothesis implantations, which have culminated in 2008. All in all, women have been treated 3-fold higher than men regarding hemiarthroplasty, total shoulder arthroplasties or reversed total shoulder arthroplasties. Under the age of 60 years the majority of treated patients were male. CONCLUSION: Since 2005 shoulder arthroplasties are still increasing in Germany, whereas a slight reduction could be detected for shoulder hemiarthroplasty from 2009 up until 2012. Meanwhile total shoulder arthroplasties and reversed total shoulder arthroplasties are still increasing. Women have experienced a 3-fold higher hemiarthroplasty, total shoulder and reversed shoulder arthroplasties than men except for individual younger than 60 years.

Elbow Positioning and Joint Insufflation Substantially Influence Median and Radial Nerve Locations.

BACKGROUND: The median and radial nerves are at risk of iatrogenic injury when performing arthroscopic arthrolysis with anterior capsulectomy. Although prior anatomic studies have identified the position of these nerves, little is known about how elbow positioning and joint insufflation might influence nerve locations. QUESTIONS/PURPOSES: In a cadaver model, we sought to determine whether (1) the locations of the median and radial nerves change with variation of elbow positioning; and whether (2) flexion and joint insufflation increase the distance of the median and radial nerves to osseous landmarks after correcting for differences in size of the cadaveric specimens. METHODS: The median and radial nerves were marked with a radiopaque thread in 11 fresh-frozen elbow specimens. Three-dimensional radiographic scans were performed in extension, in 90° flexion, and after joint insufflations in neutral rotation, pronation, and supination. Trochlear and capitellar widths were analyzed. The distances of the median nerve to the medial and anterior edge of the trochlea and to the coronoid were measured. The distances of the radial nerve to the lateral and anterior edge of the capitulum and to the anterior edge of the radial head were measured. We analyzed the mediolateral nerve locations as a percentage function of the trochlear and capitellar widths to control for differences regarding the size of the specimens. RESULTS: The mean distance of the radial nerve to the lateral edge of the capitulum as a percentage function of the capitellar width increased from 68% ± 17% in extension to 91% ± 23% in flexion (mean difference = 23%; 95% confidence interval [CI], 5%-41%; p = 0.01). With the numbers available, no such difference was observed regarding the location of the median nerve in relation to the medial border of the trochlea (mean difference = 5%; 95% CI, -13% to 22%; p = 0.309). Flexion and joint insufflation increased the distance of the nerves to osseous landmarks. The mean distance of the median nerve to the coronoid tip was 5.4 ± 1.3 mm in extension, 9.1 ± 2.3 mm in flexion (mean difference = 3.7 mm; 95% CI, 2.04-5.36 mm; p < 0.001), and 12.6 ± 3.6 mm in flexion and insufflation (mean difference = 3.5 mm; 95% CI, 0.81-6.19 mm; p = 0.008). The mean distance of the radial nerve to the anterior edge of the radial head increased from 4.7 ± 1.8 mm in extension to 7.7 ± 2.7 mm in flexion (mean difference = 3.0 mm; 95% CI, 0.96-5.04 mm; p = 0.005) and to 11.9 ± 3.0 mm in flexion with additional joint insufflation (mean difference = 4.2 mm; 95% CI, 1.66-6.74 mm; p = 0.002). CONCLUSIONS: The radial nerve shifts medially during flexion from the lateral to the medial border of the inner third of the capitulum. The median nerve is located at the medial quarter of the joint. The distance of the median and radial nerves to osseous landmarks doubles from extension to 90° flexion and triples after joint insufflation. CLINICAL RELEVANCE: Elbow arthroscopy with anterior capsulectomy should be performed cautiously at the medial aspect of the joint to avoid median nerve lesions. Performing arthroscopic anterior capsulectomy in flexion at the lateral aspect of the joint and in slight extension at the medial edge of the capitulum could enhance safety of this procedure.

Is an extension of the safe zone possible without jeopardizing the proximal radioulnar joint when performing a radial head plate osteosynthesis?

BACKGROUND: Proximal radial fractures are common elbow injuries. Because of the fracture pattern, stability criteria, or plate configuration, a plate position outside the "safe zone" (SZ) may be required in some cases when performing a radial head plate osteosynthesis. We examined the gross anatomy of the radial head and analyzed different so-called low-profile and precontoured radial head and neck plates with respect to the SZ. MATERIALS AND METHODS: Macroscopic measurements of the radial head and neck of 22 formalin-fixed human cadaveric upper extremities were obtained. The SZ was determined by maximum forearm rotation. If the edge of a plate could be extended beyond the respective SZ boundary without jeopardizing the proximal radioulnar joint (PRUJ) in maximum forearm rotation, a new plate-specific SZ boundary was set. RESULTS: The mean SZ was 133° (SD, 14°). Among the 5 plates studied, only the 2 radial neck designs allowed the anterior edge of the plate to partially pass the lesser sigmoid notch of the ulna and consequently afforded a significant extension of the SZ in maximum pronation. All 3 radial head designs had to remain within the SZ to avoid interference with the PRUJ. A safe plate position depends on individual plate dimensions, particularly the proximal plate width, and the diameter of the radial head. The smaller the head diameter, the more accurately a plate must be placed within the SZ. CONCLUSIONS: If an extension of the SZ in radial head plate osteosynthesis is not essential, we recommend respecting the SZ to minimize the possibility of interference with the PRUJ.

The course of the median and radial nerve across the elbow: an anatomic study.

INTRODUCTION: Nerve transection has been described as complication of arthroscopic elbow arthrolysis. Therefore, the goal of this study was to define bony landmarks for intraoperative orientation regarding the location of the median and radial nerve. METHODS: In 22 formalin-fixated upper extremities, the radial and median nerves were dissected and marked with respect to their native course. A 3D X-ray scan was performed. The distances of the radial nerve to the radial head (R1), the capitulum (R2), and its lateral border (RC) were measured. The location of the radial nerve in relation to the transversal diameter of the humeral condyle (HC) was calculated. Similarly, the distances of the median nerve to the trochlea (M1), the medial border of the trochlea (M2), and its relation to HC were calculated. RESULTS: The mean value for R1 was 8 mm (±2.9 mm), for R2 was 11.3 mm (±3.8 mm), and for RC was 10.6 mm (±5.1 mm). RC/HC averaged 24 % (±11 %). M1 averaged 11.7 mm (±5.2 mm), and M2 was 2.4 mm (±4.1 mm). M2/HC averaged 6 % (±9 %). CONCLUSIONS: The radial nerve is located ventral to the central third of the capitulum. The median nerve lies ventral to the medial quarter of the humeral condyle. When performing arthroscopic arthrolysis, this information should be kept in mind during anterior capsulectomy.

Do the radial head prosthesis components fit with the anatomical structures of the proximal radioulnar joint?

PURPOSE: The fitting accuracy of radial head components has been investigated in the capitulo-radial joint, and reduced contact after prosthetic replacement of the radial head has been observed. The kinematics of the proximal radioulnar joint (PRUJ) are affected by radial head arthroplasty as well, but have not yet been investigated in this regard. METHODS: The elbow joints of 60 upper extremities of formalin-fixed body donors were disarticulated to obtain a good view of the PRUJ. Each specimen was mounted on the examining table and radial head position in the native PRUJ was assessed in neutral position, full pronation, and full supination. Measurements were repeated after implantation of mono- and bi-polar prostheses. RESULTS: Analysis of the distribution of the joint contacts in the compartments showed significant differences after radial head replacement. In comparison to the native joint, after bipolar and monopolar radial head replacement, the physiological shift of the proximal radius was altered. DISCUSSION: The physiological shift of the joint contact of the radial head from anterior to posterior during forearm rotation that was found in the native joint in our cadaver model was not observed after prosthetic replacement. With higher conformity and physiological kinematic of radial head prostheses, possibly lower shear forces and lower contact pressures would be generated. CLINICAL RELEVANCE: The tested radial head prostheses do not replicate the physiological kinematics of the radial head. Further development in the prosthesis design has to be made. The meticulous reconstruction of the annular ligament seems to be of importance to increase joint contact.

Anatomical fit of seven different palmar distal radius plates.

INTRODUCTION: The purpose of this study was to compare the anatomical fit of different, precontoured palmar distal radius plates. METHODS: The anatomical fit of seven different types of palmar distal radius plates [Königsee variable fixed-angle radius plate 7/3-hole, Königsee variable fixed-angle radius plate 5/3-hole (Allendorf, Germany), Medartis 2.5 Adaptive TriLock, Medartis 2.5 TriLock, Medartis 2.5 TriLock extraarticular, (Basel, Switzerland), Synthes VA-LCP distal two-column-radius, Synthes LCP extraarticular (Bettlach, Switzerland)] were investigated in 25 embalmed human cadaveric radii. An imprint of the space between the well-positioned plate and the distal radius was attained using a silicone mass and the maximum height of the silicone imprint was digitally measured. The mean maximum imprint height was compared between the seven plates using an analysis of variance with repeated measures and Bonferroni correction for multiple comparisons. RESULTS: The mean maximum distance between the plates and the radial cortex was <2 mm for all plates. The greatest difference was found with the Medartis Adaptive (1.99 ± 0.45 mm) and the least difference with the Synthes two-column (1.56 ± 0.76 mm), this difference being statistically significant (p = 0.005). CONCLUSION: Although there was no complete congruency between the plates and the radial cortex, all distal palmar radius plates investigated in this study presented a reasonable anatomical shape. The Synthes VA-LCP distal two-column-radius plate palmar showed the best anatomical fit. A low profile and optimized anatomical precontouring minimizes irritation of the surrounding soft tissues and should be considered with plate design and implant choice.

Course of the radial nerve in relation to the center of rotation of the elbow--the need for a rational safe zone for lateral pin placement.

PURPOSE: To investigate the course and variability of the radial nerve along the lateral humerus in relation to the center of rotation of the elbow joint in the context of lateral pin placement for hinged external fixation. METHODS: A total of 95 formalin-fixed upper extremities were dissected. The course of the radial nerve along the lateral aspect of the humerus was measured at 3 landmarks with respect to the center of rotation of the elbow. We analyzed the data and the landmark positions correlated with the length of the humerus. RESULTS: The measured positions of 3 landmarks of the radial nerve in the lateral aspect of the humerus ranged from 19% to 43% of the length of the humerus and were located, on average, 6.0, 9.7, and 13.5 cm from the lateral center of rotation. CONCLUSIONS: These data help predict the humeral course of the radial nerve and define a safe zone for pin implantation. However, because of variability in the course of the radial nerve, a safe zone cannot fully ensure prevention of iatrogenic injury to the nerve. The safest method of pin application remains mini-open dissection and visual implantation. CLINICAL RELEVANCE: Based on this cadaveric study, it is not possible to define a rational safe zone. The safest method of pin application for dynamic external fixation of the elbow is to perform a mini-open dissection with direct visualization.

Sequence of the Essex-Lopresti lesion--a high-speed video documentation and kinematic analysis.

BACKGROUND AND PURPOSE: The pathomechanics of the Essex-Lopresti lesion are not fully understood. We used human cadavers and documented the genesis of the injury with high-speed cameras. METHODS: 4 formalin-fixed cadaveric specimens of human upper extremities were tested in a prototype, custom-made, drop-weight test bench. An axial high-energy impulse was applied and the development of the lesion was documented with 3 high-speed cameras. RESULTS: The high-speed images showed a transversal movement of the radius and ulna, which moved away from each other in the transversal plane during the impact. This resulted into a transversal rupture of the interosseous membrane, starting in its central portion, and only then did the radius migrate proximally and fracture. The lesion proceeded to the dislocation of the distal radio-ulnar joint and then to a full-blown Essex-Lopresti lesion. INTERPRETATION: Our findings indicate that fracture of the radial head may be preceded by at least partial lesions of the interosseous membrane in the course of high-energy axial trauma.

Tension band wiring in olecranon fractures: the myth of technical simplicity and osteosynthetical perfection.

PURPOSE: The tension band wiring (TBW) technique is a common treatment for the fixation of olecranon fractures with up to three fragments. The literature and surgeons describe TBW as an uncomplicated, always available and convenient operation producing excellent results. The purpose of this study was to determine whether TBW is more ambitious than believed or the procedure provides an increased level of tolerance concerning the surgical technique. METHODS: This study reviewed 239 TBW cases in patients with olecranon fractures or osteotomies. We reviewed a total of 2,252 X-rays for ten operative imperfections: (1) nonparallel K-wires, (2) long K-wires, (3) K-wires extending radially outwards, (4) insufficient fixation of the proximal ends of the K-wires, (5) intramedullary K-wires, (6) perforation of the joint surface, (7) single wire knot, (8) jutting wire knot(s), (9) loose figure-of-eight configuration, and (10) incorrect repositioning. RESULTS: On average, there were 4.24 imperfections per intervention in the cases reviewed. A total of 1,014 of 2,390 possible imperfections were detected. The most frequent imperfections were insufficient fixation of the proximal ends of the K-wires (91% of all cases), the use of a single wire knot (78%) and nonparallel K-wires (72%). Mayo IIa (n = 188) was the most common fracture type. CONCLUSIONS: Our results and the number of complications described by the literature together support the conclusion that TBW is not as easy as surgeons and the literature suggest. Although bone healing and the functional results of TBW are excellent in most cases, the challenges associated with this operation are underestimated. LEVEL OF EVIDENCE: IV, treatment study.

The treatment of proximal humeral fracture in adults.

BACKGROUND: The incidence of proximal humeral fractures lies between 105 and 342 per 100 000 persons per year. Around the world, this type of fracture remains a major challenge for treating surgeons. While non-displaced fractures can be managed conservatively, displaced ones are often treated surgically. METHODS: Selective literature review. RESULTS: There are still no evidence-based schemes or guidelines for the treatment of proximal humeral fractures, and very few prospective randomized trials are available. The few that have been published recently show a trend in favor of conservative treatment, but they were carried out on small groups of patients and their findings are not directly generalizable. For younger patients, the goal of treatment is generally anatomical repositioning and osteosynthetic stabilization; for older patients, primary treatment with a prosthesis is a further option. Depending on the mode of treatment, complications can arise such as shoulder stiffness, necrosis of the humeral head, pain, infection, loss of reposition, and "cutting out." CONCLUSION: Current evidence supports the individualized treatment of proximal humeral fractures. Treatment decisions must always be made jointly with the patient in consideration of his or her individual needs and characteristics. Particularly for elderly patients, the possibility of conservative treatment should be carefully considered. If conservative treatment is not possible, then the type of operation performed should also be a function of the surgeon's individual skills and experience with particular types of implant.

Locking-plate osteosynthesis versus intramedullary nailing for fixation of olecranon fractures: a biomechanical study.

PURPOSE: Intramedullary nailing and locked plating for fixation of olecranon fractures has recently gained popularity. However, these two new technologies have not been compared for their biomechanical efficacy. The aim of this study was to evaluate the biomechanical stability of two newly designed fracture fixation devices for treating olecranon fractures during dynamic continuous loading: the ION intramedullary locking nail and the LCP precontoured locking compression plate. METHODS: Simulated oblique olecranon fractures were created in eight pairs of fresh-frozen cadaver ulnae and stabilised using either the LCP or ION. Specimens were then subjected to continuous dynamic loading (from 25 to 200 N), with a continuous angle alteration between 0° and 90° of flexion, to perform a matched-pairs comparison. Significant differences in the distance between markers surrounding the fracture gap was determined using the Wilcoxon test after four and 300 loading cycles. RESULTS: The ION resulted in significantly less displacement in the fracture gap at 0° extension (P = 0.036), 45° flexion (P = 0.035) and 90° flexion (P = 0.017) after 300 cycles of continuous loading. The measured displacements were small and were probably not of clinical significance. No mechanical failure or hardware migration was seen with either fixation technique. CONCLUSION: This study shows significantly less micromotion for the ION than for the LCP in treating oblique olecranon fractures after 300 cycles of dynamic loading. Both implant types could be appropriate surgical techniques for fixation of selected olecranon fractures and osteotomies.

Jamming of fingers: an experimental study to determine force and deflection in participants and human cadaver specimens for development of a new bionic test device for validation of power-operated motor vehicle side door windows.

The deformability of human fingers is central to addressing the real-life hazard of finger jamming between the window and seal entry of a power-operated motor vehicle side door window. The index and little fingers of the left hand of 109 participants and of 20 cadaver specimens were placed in a measurement setup. Participants progressively jammed their fingers at five different dorsal-palmar jam positions up to the maximum tolerable pain threshold, whereas the cadaver specimens were jammed up to the maximum possible deflection. Force-deflection curves were calculated corresponding to increasing deflection of the compressed tissue layers of the fingers. The average maximum force applied by the participants was 42 N to the index finger and 35 N to the little finger. In the cadaver fingers, the average of the maximum force applied was 1886 N for the index finger and 1833 N for the little finger. In 200 jam positions, 25 fractures were observed on radiographs; fractures occurred at an average force of 1485 N. These data assisted the development of a prototype of a bionic test device for more realistic validation of power-operated motor vehicle windows.

The anatomy of the proximal radius: implications on fracture implant design.

BACKGROUND: The proximal radius features a complex anatomy. Several studies have been published on the anatomy using different technical approaches; however, most of these studies were conducted with a special focus on parameters relevant to radial prosthetic design. The purpose of our study was to explore the complex geometry of the proximal radius with regard to fracture implant design. METHODS: Our computed tomography-based measurements of 78 multiplanar reformatted radii allow for exact assessment of its geometry and offer a scientific rationale towards the design of fracture implants. We conducted measurements on the radial head, the radial neck, the radial tuberosity, the radial head-to-neck angle, and the safe zone. RESULTS: A wide range of normal anatomy has been demonstrated for all parameters. Sex differences are statistically significant in all registered parameters, except the radial head-to-neck angle. Although measurements of maximum vs minimum radial head, neck, and tuberosity diameters show close correlation, diameter-to-length correlations, such as radial head diameter vs radial head height and radial neck diameter vs radial neck length, are low. CONCLUSIONS: Besides the wide range in size, intraindividual parameter variations have to be taken into account in the design of anatomically precontoured plates. The results of this study indicate that these plates will still need to offer the ability of "bend to match."