New dynamic suture material for tendon transfer surgeries in the upper extremity - a biomechanical comparative analysis

BACKGROUND

Early mobilization after tendon surgery is crucial to avoid commonly observed postoperative soft tissue adhesions. Recently, a new suture was introduced (DYNACORD; DC) with a salt-infused silicone core designed to minimize laxity and preserve consistent tissue approximation in order to avoid gap formation and allow early mobilization.

AIMS

To compare the biomechanical competence of DC against a conventional high strength suture (FiberWire; FW) in a human cadaveric tendon transfer model with an early rehabilitation protocol.

METHODS

Sixteen tendon transfers (flexor digitorum superficialis (FDS) IV to flexor pollicis longus (FPL)) were performed in 8 pairs human cadaveric forearms using either DC or FW. Markings were set 0.8 cm proximally and 0.7 cm distally to the level of the interweaving zone of the transfer. All specimens underwent repetitive thumb flexion against resistance in 9 intermittent series of 300 cycles each, simulating an aggressive postoperative rehabilitation protocol. After each series, the distance of the proximal marker to the interweaving zone (proximal), the length of the interweaving zone (intermediate) and the distance of the distal marker to the interweaving zone (distal) were measured.

RESULTS

Pooled data over all nine series, normalized to the immediate postoperative status, demonstrated no significant differences between FW and DC (p ≥ 0.355) for the proximal and distal markers. However, at the intermediate zone, DC was associated with significant length shortening (p < 0.001) compared to FW without significant length changes (p = 0.351). Load to catastrophic failure demonstrated significant higher forces in FW (p = 0.011). Nevertheless, due to failure mainly proximal or distal of the transfer zone, these loads are not informative.

CONCLUSION

From a biomechanical perspective, DC preserved tissue approximation and might be considered as a valid alternative to conventional high-strength sutures in tendon transfer surgery. DC might allow for a shorter interweaving zone and a more aggressive early postoperative rehabilitation program, possibly avoiding commonly observed postoperative soft tissue adhesions and stiffness.

Digitally enhanced hands-on surgical training (DEHST) enhances the performance during freehand nail distal interlocking

PURPOSE

Freehand distal interlocking of intramedullary nails remains a challenging task. Recently, a new training device for digitally enhanced hands-on surgical training (DEHST) was introduced, potentially improving surgical skills needed for distal interlocking.

AIM

To evaluate whether training with DEHST enhances the performance of novices (first-year residents without surgical experience in freehand distal nail interlocking).

METHODS

Twenty novices were randomly assigned to two groups and performed distal interlocking of a tibia nail in mock operation under operation-room-like conditions. Participants in Group 1 were trained with DEHST (five distal interlocking attempts, 1 h of training), while those in Group 2 did not receive training. Time, number of X-rays shots, hole roundness in the X-rays projection and hit rates were compared between the groups.

RESULTS

Time to complete the task [414.7 s (range 290-615)] and X-rays exposure [17.8 µGcm2 (range 9.8-26.4)] were significantly lower in Group 1 compared to Group 2 [623.4 s (range 339-1215), p = 0.041 and 32.6 µGcm2 (range 16.1-55.3), p = 0.003]. Hole projections were significantly rounder in Group 1 [95.0% (range 91.1-98.0) vs. 80.8% (range 70.1-88.9), p < 0.001]. In Group 1, 90% of the participants achieved successful completion of the task in contrast to a 60% success rate in Group 2. This difference was not statistically significant (p = 0.121).

CONCLUSIONS

In a mock-operational setting, training with DEHST significantly enhanced the performance of novices without surgical experience in distal interlocking of intramedullary nails and hence carries potential to improve safety and efficacy of this important and demanding surgical task to steepen the learning curve without endangering patients.

LEVEL OF EVIDENCE

II.

Mid-term Clinical Outcome of Microvascular Gracilis Muscle Flaps for Defects of the Hand

PURPOSE

Gracilis muscle flaps are useful to cover defects of the hand. However, there are currently no studies describing outcome measurements after covering soft tissue defects using free flaps in the hand.

AIM

To analyze mid-term results of gracilis muscle flap coverage for defects on the hand, with regard to functional and esthetic integrity.

METHODS

16 patients aged 44.3 (range 20-70) years were re-examined after a mean follow-up of 23.6 (range 2-77) months. Mean defect size was 124 (range 52-300) cm2 located palmar (n = 9), dorsal (n = 6), or radial (n = 1). All flaps were performed as microvascular muscle flaps, covered by split thickness skin graft.

RESULTS

Flaps survived in 15 patients. 6 patients required reoperations. Reasons for revisions were venous anastomosis failure with total flap loss (n = 1) requiring a second gracilis muscle flap; necrosis at the tip of the flap (n = 1) with renewed split thickness skin cover. A surplus of the flap (n = 2) required flap thinning and scar corrections were performed in 2 patients. Mean grip strength was 25% (range 33.3-96.4%) compared to the contralateral side and mean patient-reported satisfaction 1.4 (range 1-3) (1 = excellent; 4 = poor).

CONCLUSIONS

Gracilis muscle flaps showed a survival rate of 94%. Patients showed good clinical outcomes with acceptable wrist movements and grip strength as well as high reported satisfaction rates. Compared to fasciocutaneous free flaps, pliability and thinness especially on the palmar aspect of the hand are advantageous. Hence, covering large defects of the hand with a gracilis muscle flap can be a very satisfactory procedure.

LEVEL OF EVIDENCE

IV observational.

New generation of superior single plating vs. low-profile dual minifragment plating in diaphyseal clavicle fractures: a biomechanical comparative study

BACKGROUND

Recently, a new generation of superior clavicle plates was developed featuring the variable-angle locking technology for enhanced screw positioning and a less prominent and optimized plate-to-bone fit design. On the other hand, minifragment plates in dual plating mode have demonstrated promising clinical results. The aim of the current study was to compare the biomechanical competence of single superior plating using the new-generation plate vs. dual plating using low-profile minifragment plates.

METHODS

Sixteen paired human cadaveric clavicles were pairwise assigned to 2 groups for instrumentation with either a superior 2.7-mm variable-angle locking compression plate (group 1), or with one 2.5-mm anterior combined with one 2.0-mm superior matrix mandible plate (group 2). An unstable clavicle shaft fracture (AO/OTA 15.2C) was simulated by means of a 5-mm osteotomy gap. Specimens were cyclically tested to failure under craniocaudal cantilever bending, superimposed with bidirectional torsion around the shaft axis, and monitored via motion tracking.

RESULTS

Initial construct stiffness was significantly higher in group 2 (9.28 ± 4.40 N/mm) compared to group 1 (3.68 ± 1.08 N/mm), P = .003. The amplitudes of interfragmentary motions in terms of axial and shear displacement, fracture gap opening and torsion, over the course of 12,500 cycles were significantly higher in group 1 compared to group 2, P ≤ .038. Cycles to 2 mm shear displacement were significantly lower in group 1 (22,792 ± 4346) compared to group 2 (27,437 ± 1877), P = .047.

CONCLUSION

From a biomechanical perspective, low-profile 2.5/2.0-mm dual plates could be considered as a useful alternative for diaphyseal clavicle fracture fixation, especially in less common unstable fracture configurations.

Substitutional semi-rigid osteosynthesis technique for treatment of unstable pubic symphysis injuries: a biomechanical study

BACKGROUND/PURPOSE

The surgical fixation of a symphyseal diastasis in partially or fully unstable pelvic ring injuries is an important element when stabilizing the anterior pelvic ring. Currently, open reduction and internal fixation (ORIF) by means of plating represents the gold standard treatment. Advances in percutaneous fixation techniques have shown improvements in blood loss, surgery time, and scar length. Therefore, this approach should also be adopted for treatment of symphyseal injuries. The technique could be important since failure rates, following ORIF at the symphysis, remain unacceptably high. The aim of this biomechanical study was to assess a semi-rigid fixation technique for treatment of such anterior pelvic ring injuries versus current gold standards of plate osteosynthesis.

METHODS

An anterior pelvic ring injury type III APC according to the Young and Burgess classification was simulated in eighteen composite pelvises, assigned to three groups (n = 6) for fixation with either a single plate, two orthogonally positioned plates, or the semi-rigid technique using an endobutton suture implant. Biomechanical testing was performed in a simulated upright standing position under progressively increasing cyclic loading at 2 Hz until failure or over 150,000 cycles. Relative movements between the bone segments were captured by motion tracking.

RESULTS

Initial quasi-static and dynamic stiffness, as well as dynamic stiffness after 100,000 cycles, was not significantly different among the fixation techniques (p ≥ 0.054).). The outcome measures for total displacement after 20,000, 40,000, 60,000, 80,000, and 100,000 cycles were associated with significantly higher values for the suture technique versus double plating (p = 0.025), without further significant differences among the techniques (p ≥ 0.349). Number of cycles to failure and load at failure were highest for double plating (150,000 ± 0/100.0 ± 0.0 N), followed by single plating (132,282 ± 20,465/91.1 ± 10.2 N), and the suture technique (116,088 ± 12,169/83.0 ± 6.1 N), with significantly lower values in the latter compared to the former (p = 0.002) and no further significant differences among the techniques (p ≥ 0.329).

CONCLUSION

From a biomechanical perspective, the semi-rigid technique for fixation of unstable pubic symphysis injuries demonstrated promising results with moderate to inferior behaviour compared to standard plating techniques regarding stiffness, cycles to failure and load at failure. This knowledge could lay the foundation for realization of further studies with larger sample sizes, focusing on the stabilization of the anterior pelvic ring.

Helical Plating Compared with Straight Plating and Nailing for Treatment of Proximal Third Humeral Shaft Fractures-A Biomechanical Study

Background and Objectives: The surgical treatment of proximal humeral shaft fractures usually considers application of either long straight plates or intramedullary nails. By being able to spare the rotator cuff and avoid the radial nerve distally, the implementation of helical plates might overcome the downsides of common fixation methods. The aims of the current study were (1) to explore the biomechanical competence of different plate designs and (2) to compare their performance versus the alternative treatment option of using intramedullary nails. Materials and Methods: Twenty-four artificial humeri were assigned to the following four groups for simulation of an unstable proximal humeral shaft fracture and instrumentation: Group 1 (Straight-PHILOS), Group 2 (MULTILOC-Nail), Group 3 (45°-Helical-PHILOS), and Group 4 (90°-Helical-PHILOS). All specimens underwent non-destructive, quasi-static biomechanical testing under loading in axial compression, torsion in internal/external rotation, and pure bending in four directions, accompanied by motion tracking. Results: Axial stiffness/displacement in Group 2 was significantly higher/smaller than in all other groups (p ≤ 0.010). Torsional displacement in Group 2 was significantly bigger than in all other groups (p ≤ 0.017). Significantly smaller coronal plane displacement was identified in Group 2 versus all other groups (p < 0.001) and in Group 4 versus Group 1 (p = 0.022). Significantly bigger sagittal plane displacement was detected in Group 4 versus all other groups (p ≤ 0.024) and in Group 1 versus Group 2 (p < 0.001). Conclusions: Intramedullary nails demonstrated higher axial stiffness and smaller axial interfragmentary movements compared with all investigated plate designs. However, they were associated with bigger torsional movements at the fracture site. Although 90°-helical plates revealed bigger interfragmentary movements in the sagittal plane, they demonstrated improved resistance against displacements in the coronal plane when compared with straight lateral plates. In addition, 45°-helical plates manifested similar biomechanical competence to straight plates and may be considered a valid alternative to the latter from a biomechanical standpoint.

Anterior column acetabulum fracture fixation with a screw-augmented acetabular cup-a biomechanical feasibility study

BACKROUND

The beneficial effects of unrestricted postoperative full weight bearing for elderly patients suffering hip fractures have been demonstrated. However, there is still existing disagreement regarding acetabular fractures.The aim of this biomechanical study was to evaluate the initial load bearing capabilities of different fixation constructs of anterior column fractures (ACFs) in osteoporotic bone.

METHODS

Artificial pelvises with ACFs were assigned to three groups (n = 8) and fixed with either a 7.3 mm partially threaded antegrade cannulated screw (group AASS), an anteriorly placed 3.5 mm plate (group AAPF), or a press-fit acetabular cup with screw augmentation (group AACF). All specimens underwent ramped loading from 20 N preload to 200 N at a rate of 18 N/s, followed by progressively increasing cyclic testing at 2 Hz until failure performed at a rate of 0.05 N/cycle. Relative displacements of the bone fragments were monitored by motion tracking.

FINDINGS

Initial stiffness (N/mm) was 118.5 ± 34.3 in group AASS, 100.4 ± 57.5 in group AAPF, and 92.9 ± 44.0 in group AACF, with no significant differences between the groups, p = 0.544. Cycles to failure were significantly higher in groups AACF (8364 ± 2243) and AAPF (7827 ± 2881) compared to group AASS (4440 ± 2063), p ≤ 0.041.

INTERPRETATION

From a biomechanical perspective, the minimally invasive cup fixation with screw augmentation demonstrated comparable stability to plate osteosynthesis of ACFs in osteoporotic bone. The results of the present study do not allow to conclusively answer whether immediate full weight bearing following cup fixation shall be allowed. Given its similar performance to plate osteosynthesis, this remains rather an utopic wish and a more conservative approach deems more reasonable.

Quality of Life and Working Conditions of Hand Surgeons-A National Survey

Background and Objectives: Providing high-quality care for patients in hand surgery is an everyday endeavor. However, the quality of life (QoL) and working conditions of hand surgeons ensuring these high-quality services need to be investigated. The aim of this study was to evaluate the QoL and working conditions of Swiss hand surgeons. Materials and Methods: A national survey with Swiss hand surgeons was conducted. Standardized questionnaires were completed anonymously online. Core topics included working conditions, QoL, satisfaction with the profession, and aspects of private life. Results: A total of 250 hand surgeons were invited to participate, of which 110 (44.0%) completed the questionnaire. Among all participants, 43.6% stated that they are on call 4-7 days per month, versus 8.2% never being on call. Overall, 84.0% of the residents, 50.0% of the senior physicians, 27.6% of the physicians in leading positions, and 40.6% of the senior consultants/practice owners, as well as 55.1% of the female and 44.3% of the male respondents, felt stressed by their job, even during holidays and leisure time. Out of all participants, 85.4% felt that work affects private relationships negatively. Despite the reported stress, 89.1% would choose hand surgery as a profession again. Less on-call duty (29.1%) and better pay (26.4%) are the most prioritized factors for attractiveness of a position at a hospital. Conclusions: The QoL of Swiss hand surgeons is negatively affected by their workload and working hours. Residents, senior physicians and female surgeons suffer significantly more often from depression, burnout or chronic fatigue in comparison to leading positions, senior consultants/practice owners and male surgeons. Better pay or less on-call duty would make the work more attractive in acute care hospitals.

Antegrade Posterior Column Acetabulum Fracture Screw Fixation via Posterior Approach: A Biomechanical Comparative Study

Background and Objectives: Minimally invasive surgeries for acetabulum fracture fixation are gaining popularity due to their known advantages versus open reduction and internal fixation. Antegrade or retrograde screw fixation along the long axis of the posterior column of the acetabulum is increasingly applied in surgical practice. While there is sufficient justification in the literature for the application of the anterior approach, there is a deficit of reports related to the posterior approach. The aim of this study was to evaluate the biomechanical competence of posterior column acetabulum fracture fixation through antegrade screw placement using either a standard cannulated screw or a cannulated compression headless screw (CCHS) via posterior approach. Materials and Methods: Eight composite pelvises were used, and a posterior column acetabulum fracture according to the Letournel Classification was simulated on both their left and right sides via an osteotomy. The sixteen hemi-pelvic specimens were assigned to two groups (n = 8) for either posterior column standard screw (group PCSS) or posterior column CCHS (group PCCH) fixation. Biomechanical testing was performed by applying steadily increased cyclic load until failure. Interfragmentary movements were investigated by means of motion tracking. Results: Initial stiffness demonstrated significantly higher values in PCCH (163.1 ± 14.9 N/mm) versus PCSS (133.1 ± 27.5 N/mm), p = 0.024. Similarly, cycles and load at failure were significantly higher in PCCH (7176.7 ± 2057.0 and 917.7 ± 205.7 N) versus PCSS (3661.8 ± 1664.5 and 566.2 ± 166.5 N), p = 0.002. Conclusion: From a biomechanical perspective, CCHS fixation demonstrates superior stability and could be a valuable alternative option to the standard cannulated screw fixation of posterior column acetabulum fractures, thus increasing the confidence in postoperative full weight bearing for both the patient and treating surgeon. Whether uneventful immediate postoperative full weight bearing can be achieved with CCHS fixation should primarily be investigated in further human cadaveric studies with a larger sample size.

Biomechanical performance of a novel light-curable bone fixation technique

Traumatic bone fractures are often debilitating injuries that may require surgical fixation to ensure sufficient healing. Currently, the most frequently used osteosynthesis materials are metal-based; however, in certain cases, such as complex comminuted osteoporotic fractures, they may not provide the best solution due to their rigid and non-customizable nature. In phalanx fractures in particular, metal plates have been shown to induce joint stiffness and soft tissue adhesions. A new osteosynthesis method using a light curable polymer composite has been developed. This method has demonstrated itself to be a versatile solution that can be shaped by surgeons in situ and has been shown to induce no soft tissue adhesions. In this study, the biomechanical performance of AdhFix was compared to conventional metal plates. The osteosyntheses were tested in seven different groups with varying loading modality (bending and torsion), osteotomy gap size, and fixation type and size in a sheep phalanx model. AdhFix demonstrated statistically higher stiffnesses in torsion (64.64 ± 9.27 and 114.08 ± 20.98 Nmm/° vs. 33.88 ± 3.10 Nmm/°) and in reduced fractures in bending (13.70 ± 2.75 Nm/mm vs. 8.69 ± 1.16 Nmm/°), while the metal plates were stiffer in unreduced fractures (7.44 ± 1.75 Nm/mm vs. 2.70 ± 0.72 Nmm/°). The metal plates withstood equivalent or significantly higher torques in torsion (534.28 ± 25.74 Nmm vs. 614.10 ± 118.44 and 414.82 ± 70.98 Nmm) and significantly higher bending moments (19.51 ± 2.24 and 22.72 ± 2.68 Nm vs. 5.38 ± 0.73 and 1.22 ± 0.30 Nm). This study illustrated that the AdhFix platform is a viable, customizable solution that is comparable to the mechanical properties of traditional metal plates within the range of physiological loading values reported in literature.

Evaluation of cannulated compression headless screws as an alternative implant for superior pubic ramus fracture fixation: a biomechanical study

BACKGROUND/PURPOSE

Pubic ramus fractures account for the most common types of pelvic fractures. The standard surgical approach for superior pubic ramus fractures (SPRF) is a minimally invasive percutaneous screw fixation. However, percutaneous closed reduction and internal fixation of anterior pelvic ring injuries have high failure rates of up to 15%. The aim of this biomechanical study was to evaluate the stability of SPRF following stabilization with retrograde placed cannulated compression headless screw (CCHS) versus conventional fully and partially threaded screws in an artificial pelvic bone model.

METHODS

SPRF type II as described by Nakatani et al. was created by means of osteotomies in eighteen anatomical composite hemi-pelvises. Specimens were stratified into three groups of six specimens each (n = 6) for fixation with either a 7.3 mm partially threaded cannulated screw (group RST), a 7.3 mm fully threaded cannulated screw (group RSV), or a 7.5 mm partially threaded cannulated CCHS (group CCS). Each hemi-pelvic specimen was tested in an inverted upright standing position under progressively increasing cyclic axial loading. The peak load, starting at 200 N, was monotonically increased at a rate of 0.1 N/cycle until 10 mm actuator displacement.

RESULTS

Total and torsional displacement were associated with higher values for RST versus CCS and RSV, with significant differences between RST and CCS for both these parameters (p ≤ 0.033). The differences between RST and RSV were significant for total displacement (p = 0.020), and a trend toward significance for torsional displacement (p = 0.061) was observed. For both failure criteria 2 mm total displacement and 5° torsional displacement, CCS was associated with significantly higher number of cycles compared to RST (p ≤ 0.040).

CONCLUSION

CCHS fixation presented predominantly superior stability to the standard surgical treatment and could therefore be a possible alternative implant for retrograde SPRF screw fixation, whereas partially threaded screws in group RST were associated with inferior biomechanical stability.

The osteocutaneous SCIP flap: A detailed description of the surgical technique and retrospective cohort study of consecutive cases in a tertiary European centre

INTRODUCTION

In the era of increasing popularity of the superficial circumflex iliac perforator (SCIP) flap, osteocutaneous variants of the flap have been described as well. Despite their benefits such as customizability and low donor site morbidity, these flaps have not yet gained broad acceptance. By reviewing our case series, we aim to promote the safe application of this promising new tool in osteoplastic reconstructions.

PATIENTS AND METHODS

We performed a single-centre, retrospective chart review of all cases in which osteocutaneous SCIP-flaps were used. We describe our surgical technique and present the surgical, functional and aesthetic outcomes of the patients in our cohort.

RESULTS

Since September 2019, we have used osteocutaneous SCIP flaps in six patients, five in the extremities and one for the head and neck region. The vascularised bone segment was measured on average 4.9 cm (range 4-7 cm) x 3 cm (range 1.5-4 cm) and was combined with a skin paddle of a mean length of 14.3 cm (range 8-20 cm) and width of 6.3 cm (range 5-8 cm). One flap underwent emergency revision due to venous congestion. All flaps survived and healed uneventfully. Long-term follow-up shows adequate bony integration and stable soft tissue coverage with good functional restoration and minimal donor site morbidity.

CONCLUSION

The osteocutaneous SCIP flap provides a large and thin skin island and a "moderately sized" vascularised bone segment with minimal donor site morbidity and can be successfully used in selected cases of osteoplastic reconstruction.

A Life Dedicated to Climbing and Its Sequelae in the Fingers-A Review of the Literature

Fingers of sport climbers are exposed to high mechanical loads. This work focuses on the fingers of a 52-year-old active elite climber who was the first in mankind to master 8B (V13), 8B+ (V14) and 8C (V15) graded boulders, bringing lifelong high-intensity loads to his hands. It is therefore hypothesized that he belongs to a small group of people with the highest accumulative loads to their fingers in the climbing scene. Fingers were analyzed by means of ultrasonography, X-rays and physical examination. Soft tissue and bone adaptations, as well as the onset of osteoarthritis and finger stiffness, were found, especially in digit III, the longest and therefore most loaded digit. Finally, this article aims to provide an overview of the current literature in this field. In conclusion, elite sport climbing results in soft tissue and bone adaptations in the fingers, and the literature provides evidence that these adaptations increase over one's career. However, at later stages, radiographic and clinical signs of osteoarthritis, especially in the middle finger, seem to occur, although they may not be symptomatic.

Cortical Bone Thickness, Base Osteophyte Occurrence and Radiological Signs of Osteoarthritis in the Fingers of Male Elite Sport Climbers: A Cross-Sectional 10-Year Follow-Up Study

Background: Sport climbing places high mechanical loads on fingers. In 2012, our research group demonstrated adaptations of climbers’ cortical bones with the presence of osteophytes compared to non-climbing controls.

Objectives: 1) To investigate 10-year changes in cortical bone thickness, base osteophyte occurrence and radiological signs of osteoarthritis in the fingers of elite male sport climbers with more than 25 years of climbing history and 2) to compare cortical bone thickness, base osteophyte occurrence and radiological signs of osteoarthritis between male sport climbers and age-matched controls at the 10-year follow-up.

Methods: All 31 elite sport climbers who participated in both the baseline and 10-year follow-up assessments (follow-up rate 100%) were examined by means of X-rays. Cortical bone thickness, presence of osteophytes and signs of osteoarthritis according to Kellgren-Lawrence were obtained and compared to the baseline values 10 years earlier and to age-matched controls at the follow-up (n = 15).

Results: Significantly increased cortical bone thickness over the past 10 years was observed in climbers (mean absolute difference with 95% CI:0.98 mm (0.77 mm, 1.19 mm); p <0.001). Moreover, compared to age-matched controls, climbers had significantly thicker cortical bone at the 10-year follow-up (mean absolute difference with 95% CI:0.86 mm (0.61 mm, 1.12 mm); p <0.001). In climbers, osteophytes and clear signs of osteoarthritis were mainly seen in DIP joints. Signs of osteoarthritis according to Kellgren-Lawrence were more prevalent than 10 years before in most joints. In lateral radiographs, base osteophytes were not significantly more prevalent than 10 years before in most of the joints. The percentage of climbers who had osteophytes in any DIP (PIP) joint increased from 93.5% (67.7%) at baseline to 100% (74.2%) at the 10-year follow-up. The percentage of climbers who had clear signs of osteoarthritis according to Kellgren-Lawrence in any DIP (PIP) joint increased from 12.9% (9.7%) at baseline to 74.2% (64.5%) at 10-year follow-up. Only a few such degenerative changes were found in age-matched controls.

Conclusion: An accumulation of repetitive climbing-related stress to the fingers of elite sport climbers over the career may induce lifelong mechano-adaptation of the cortical bone thickness of all phalanges. At the 10-year follow-up, a further significant increase in radiographic signs of osteoarthritic changes was observed.

Anatomical analysis of different helical plate designs for proximal humeral shaft fracture fixation

Objective

Helical plates are preferably used for proximal humeral shaft fracture fixation with metaphyseal extension into the humeral head and potentially avoid radial nerve irritation as compared to straight plates. The aims of this study were: (1) to investigate the safety of applying different long plate designs (straight, 45°-, 90°-helical and ALPS) in MIPO-technique to the humerus and (2) to assess and compare their distances to adjacent anatomical structures at risk.

Methods

MIPO was performed in 16 human cadaveric humeri using either a straight plate (group1), a 45°-helical (group2), a 90°-helical (group3) or an ALPS (group4). Using CT-angiography, distances between brachial arteries and plates were evaluated. Following, all specimens were dissected, and distances to the axillary, radial and musculocutaneous nerve were evaluated.

Results

None of the specimens demonstrated injuries of the anatomical structures at risk after MIPO with all investigated plate designs. Closest overall distance (mm(range)) between each plate and the radial nerve was 1(1–3) in group1, 7(2–11) in group2, 14(7–25) in group3 and 6(3–8) in group4. It was significantly longer in group3 and significantly shorter in group1 as compared to all other groups, p&lt;0.001. Closest overall distance (mm(range)) between each plate and the musculocutaneous nerve was 16(8–28) in group1, 11(7–18) in group2, 3(2–4) in group3 and 6(3–8) in group4. It was significantly longer in group1 and significantly shorter in group3 as compared to all other groups, p&lt;0.001. Closest overall distance (mm(range)) between each plate and the brachial artery was 21(18–23) in group1, 7(6–7) in group2, 4(3–5) in group3 and 7(6–7) in group4. It was significantly longer in group1 and significantly shorter in group3 as compared to all other groups, p&lt;0.021.

Conclusion

MIPO with 45°- and 90°-helical plates as well as ALPS is safely feasible and showed a significant greater distance to the radial nerve compared to straight plates. However, distances remain low, and attention must be paid to the musculocutaneous nerve and the brachial artery when MIPO is used with ALPS, 45°- and 90°-helical implants. Moreover, the anterior part of the deltoid insertion will be detached when using 90°-helical and ALPS implants in MIPO-technique.

Anatomical analysis of different helical plate designs for distal femoral fracture fixation

Objective

Helical plates potentially avoid the medial neurovascular structures of the thigh. Recently, two plate designs (90°- and 180°-helix) proved similar biomechanically behavior compared to straight plates. The aims of this study were: (1) feasibility of applying 90°- and 180°-helical plates in MIPO-technique to the femur, (2) Assess the distances to adjacent anatomical structures which are at risk, (3) Compare these distances with medial straight plates, and (4) Correlate measurements performed during anatomical dissection with CT-angiography.

Methods

MIPO was performed in ten cadaveric femoral pairs using either a 90°-helical 14-hole-LCP (group1) or a 180°-helical 15-hole-LCP-DF (group2). Using CT-angiography, distances between femoral arteries and plates as well as distances between plates and perforators were evaluated. Following, specimens were dissected, and distances determined again. All plates were removed, and all measurements were repeated with straight medial plates (group3).

Results

Closest overall distances between plates and femoral arteries were 15 mm(11–19 mm) in group1, 22 mm(15–24 mm) in group2 and 6 mm(1–8 mm) in group3 with a significant difference between group1 and group3(p&lt;0.001). Distances to the nearest perforators were 24 mm(15–32 mm) in group1 and 2 mm(1–4 mm) in group2. Measurement techniques (visual after surgery and CT-angiography) showed a strong correlation of 0.972(p&lt;0.01).

Conclusion

MIPO with 90°- and 180°-helical plates is feasible and safe. Attention must be paid to the medial neurovascular structures with 90°-helical implants and to the proximal perforators with 180°-helical implants. Helical implants can avoid medial neurovascular structures compared to straight plates although care must be taken during their distally insertion. Measurements during anatomical dissection correlate with CT-angiography.

Low-profile dual mini-fragment plating of diaphyseal clavicle fractures. A biomechanical comparative analysis

Objective

Implant removal rates after clavicle plating are high. Recently, low-profile dual mini-fragment plate constructs have proven safe for the fixation of diaphyseal clavicle fractures. Therefore, the aims of this study was to investigate: (1) the biomechanical competence of different dual plate designs in terms of stiffness and cycles to failure, and (2) to compare them against 3.5 mm single superoanterior plating.

Methods

12 artificial clavicles were assigned to 2 groups and instrumented with titanium matrix mandible plates as follows: group 1 (2.5 mm anterior+2.0 mm superior) and group 2 (2.0 mm anterior+2.0 mm superior). An unstable clavicle shaft fracture (AO/OTA15.2C) was simulated. Specimens were cyclically tested to failure under craniocaudal cantilever bending, superimposed with torsion around the shaft axis and compared to previous published data of 6 locked superoanterior plates tested under the same conditions (group 3)

Results

Displacement (mm) after 5000 cycles was highest in group 3 (10.7±0.8) followed by group 2 (8.5±1.0) and group 1 (7.5±1.0), respectively. Both outcomes were significantly higher in group 3 as compared to both groups 1 and 2 (p≤0.027). Cycles to failure were highest in group 3 (19536±3586) followed by group 1 (15834±3492) and group 2 (11104±3177), being significantly higher in group 3 as compared to group 2 (p=0.004).

Conclusion

Low-profile 2.0/2.0 dual plates demonstrated similar initial stiffness compared to 3.5 mm single plates, however, they revealed significantly lower endurance to failure. Moreover, low-profile 2.5/2.0 dual plates showed significant higher initial stiffness and similar resistance to failure compared to 3.5 mm single locked plates and can therefore be considered as a useful alternative for diaphyseal clavicle fracture fixation. These results complement the promising results of several clinical studies.

Posttraumatic Carpal Instability Nondissociative

Background  Posttraumatic midcarpal instability nondissociative (CIND) is an exceptional rare condition, therefore the outcome after different treatment options remains unknown. Questions  The purpose of this study was to investigate the different treatment options for posttraumatic CIND. We also describe the different radiological and magnetic resonance imaging (MRI) findings in this patient cohort. Patients and Methods  We present outcomes of 10 patients who developed CIND following acute wrist trauma between 2007 and 2018, 3 with dorsal intercalated segment instability pattern (CIND-DISI) and 7 with volar intercalated segment instability (CIND-VISI) radiographically. Results  Three patients with CIND-VISI had satisfactory outcomes with conservative treatment. Two patients with irreducible CIND-DISI and one with CIND-VISI underwent proximal row carpectomy (PRC), two with reducible CIND-VISI had radiolunate fusion, and two with secondary osteoarthritis had total wrist fusion. All patients with CIND-DISI needed surgery, whereas only four of the seven patients with CIND-VISI needed surgery. On MRI, all three patients with CIND-DISI had rupture of the radiolunate ligament. Conclusions  The data collected in this study may provide the first step toward better understanding of the pathology for this exceptionally rare finding. In CIND-VISI, we have not seen any ligament injury in four patients. Therefore, conservative therapy is more likely to be the first step. In CIND-DISI, we recommend an operative procedure: if detected early, with ligament suture, otherwise by radiolunate fusion, PRC, or total wrist fusion. Level of Evidence  This is a Level IV study.

Long-term evolution of cartilage abnormalities and osteophytes in the fingers of elite sport climbers: A cross-sectional 10-year follow-up study

The sequelae of high mechanical stress to the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints of the fingers in elite sport climbers and its contribution to the development of osteoarthritis are still relatively unknown. The purpose of this study was to investigate the evolution of cartilage abnormalities of the PIP and DIP joints, as well as the progress of osteophytes, in the fingers of elite sport climbers with a minimum of 25 years of climbing history over the time period of the last 10 years. Moreover, their actual cartilage abnormalities and osteophyte occurrence were compared to non-climbing age-matched controls. Thirty-one elite male sport climbers and 15 male non-climbers underwent a sonographic examination of the PIP and DIP joint cartilage and osteophyte thickness in the frontal and sagittal plane of digits II-V of both hands. The same cohort had already been measured with an identical protocol 10 years earlier (follow-up rate of 100%). Compared to the baseline assessment 10 years earlier, the cartilage thickness of sport climbers has significantly decreased; however, it was still greater than in age-matched controls. Moreover, sport climbers showed significantly higher relative frequencies of osteophyte occurrence than non-climbers (all fingers and joints). Nevertheless, despite a substantial (and compared to baseline a further increased) occurrence of osteophytes in elite sport climbers, there was no association between the radiological signs of osteoarthritis and pain within the last six months prior the follow-up investigation.Highlights Long-term elite climbers show thicker cartilage and occurrence of Osteophytes in their fingers (especially Digit III) compared to controls already early in their career.Later occurrence of osteophytes increases (especially Digit II and IV) and cartilage decreases but is still thicker compared to controls. No association between those findings and pain was found.

Microcirculation After Trochanteric Femur Fractures: A Prospective Cohort Study Using Non-invasive Laser-Doppler Spectrophotometry

Proximal femur fractures represent a major healthcare problem in the aging society. High rates of post-operative infections are linked to risk factors that seem to affect local microcirculation. Patterns and time courses of alterations in microcirculation have, however, not been previously investigated. The aim of this prospective cohort study was to evaluate perioperative changes in microcirculation after trochanteric femur fractures using non-invasive laser-Doppler spectrophotometry to analyze how oxygen saturation (SO₂), hemoglobin content (Hb) and blood flow changed before and after surgery, and how these parameters were altered by implant type, gender, smoking, diabetes and age. Measurements were separately recorded for nine locations around the greater trochanter in 2, 8, and 15 mm depths, before surgery and 8, 24, 48 h, 4, 7, and 12 days after surgery in 48 patients. Three implants were compared: Dynamic Hip Screw, Gamma3 Nail, and Percutaneous Compression Plate. Surgery resulted in significant differences between the healthy and injured leg in SO₂, Hb and flow. Each parameter showed comparable values for both legs prior to surgery. Significantly higher values in SO₂ and flow were registered in women compared to men before and after surgery. Smoking caused significant increases in SO₂, Hb, and flow only in the superficial layer of the skin after surgery. Diabetes decreased blood flow at 2 and 8 mm depth and increased SO₂ at 8 and 15 mm depth after surgery. Age revealed a significant negative correlation with flow. The ability to increase the flow rate after surgery decreased with age. Comparison of implants indicated the minimally invasive implant PCCP altered microcirculation less than the DHS or the Gamma3 nail. Overall, the proximal femur fracture alone did not alter local skin microcirculation significantly in a way comparable to the effect caused by surgery. In conclusion, microcirculation after proximal femur fractures is highly affected by surgery, gender, smoking, diabetes, age and implant in ways specified in this study.

Demographic histories and genetic diversity across pinnipeds are shaped by human exploitation, ecology and life-history

A central paradigm in conservation biology is that population bottlenecks reduce genetic diversity and population viability. In an era of biodiversity loss and climate change, understanding the determinants and consequences of bottlenecks is therefore an important challenge. However, as most studies focus on single species, the multitude of potential drivers and the consequences of bottlenecks remain elusive. Here, we combined genetic data from over 11,000 individuals of 30 pinniped species with demographic, ecological and life history data to evaluate the consequences of commercial exploitation by 18th and 19th century sealers. We show that around one third of these species exhibit strong signatures of recent population declines. Bottleneck strength is associated with breeding habitat and mating system variation, and together with global abundance explains much of the variation in genetic diversity across species. Overall, bottleneck intensity is unrelated to IUCN status, although the three most heavily bottlenecked species are endangered. Our study reveals an unforeseen interplay between human exploitation, animal biology, demographic declines and genetic diversity.

Historical hunting has caused documented declines in pinnipeds, but the extent to which hunting caused genetic bottlenecks among species was unknown. Here, the authors show evidence of severe bottlenecks in several pinniped species, particularly those that breed on land.

Mutations in LZTR1 drive human disease by dysregulating RAS ubiquitination

The leucine zipper-like transcriptional regulator 1 (LZTR1) protein, an adaptor for cullin 3 (CUL3) ubiquitin ligase complex, is implicated in human disease, yet its mechanism of action remains unknown. We found that Lztr1 haploinsufficiency in mice recapitulates Noonan syndrome phenotypes, whereas LZTR1 loss in Schwann cells drives dedifferentiation and proliferation. By trapping LZTR1 complexes from intact mammalian cells, we identified the guanosine triphosphatase RAS as a substrate for the LZTR1-CUL3 complex. Ubiquitome analysis showed that loss of Lztr1 abrogated Ras ubiquitination at lysine-170. LZTR1-mediated ubiquitination inhibited RAS signaling by attenuating its association with the membrane. Disease-associated LZTR1 mutations disrupted either LZTR1-CUL3 complex formation or its interaction with RAS proteins. RAS regulation by LZTR1-mediated ubiquitination provides an explanation for the role of LZTR1 in human disease.

[Biodegradable catheters and urinary stents. When?]

One of the main wishes in the field of urinary catheters and stents is to arm them with biodegradable characteristics because we consider a failure of these devices the need for retrieval, the forgotten catheter syndrome as well as the adverse effects permanent devices cause after fulfilling their aim. The efforts focused in new designs, coatings and biomaterials aim to increase the biocompatibility of theses internal devices. Lately, there have been correct advances to answer the main challenges regarding biodegradable ureteral devices. Thus, modulation of the rate of degradation has been achieved thanks to new biomaterials and the use of copolymers that enable to choose the time of permanence as it is programmed with conventional double J catheters. Biocompatibility has improved with the use of new polymers that adapt better to the urine. Finally, one of the main problems is elimination of degraded fragments and experimentally it has be demonstrated that new designs elicit controlled degradation, from distal to proximal; using stranding and combination of copolymers degradation may be caused by dilution, reducing fragmentation to the last stages of life of the prosthesis. Moreover, it has been demonstrated that biodegradable catheters potentially may cause less urinary tract infection, less encrustation and predictably they will diminish catheter morbidity, since their degradation process reduces adverse effects. Regarding the development of biodegradable urethral stents, it is necessary to find biomaterials that enable maintaining their biomechanical properties in the long term, keeping open the urethral lumen both in patients with BPH and urethral stenosis. Modulation of the time of degradation of the prosthesis has been achieved, but the appearance of urothelial hyperplasia is still a constant in the initial phases after implantation. The development of drug eluting stents, anti-proliferative or anti-inflammatory, as well as biodegradable stents biocoated is a field from which it is expected the arrival of the solution of theses adverse effects. Therefore, many features need to be improved to obtain biodegradable stents, but over the last years some turning points have been accomplished thanks to the advances in Bioengineering, allowing to foresee safe and effective solutions in the nearest future.

Displaced intra-articular calcaneal fractures: is there a consensus on treatment in Germany?

INTRODUCTION

Open reduction in displaced intra-articular calcaneal fractures entails a high rate of wound healing deficits and infections as well as an uncertain outcome, which leads to remaining ambiguity in treatment preferences.

METHODS

Between January and July 2011, we emailed 575 German chairpersons of trauma and/or orthopaedic departments, asking them to complete a 31-question web-based survey regarding three broad domains: fracture classification, surgical treatment algorithms and risk factors for wound healing deficits.

RESULTS

The response rate was 47 %. With an incidence of 77 %, open reduction via an extended lateral approach and plate fixation was the main treatment option for displaced intra-articular fractures of the joint-depression-type (Sanders II or III). Percutaneous techniques were only preferred in individual cases, with mainly precarious wound situations (59 %) as well as in patients with a reduced general health condition (ASA 3 and 4; 41 %). The re-operation rate due to infections and wound healing deficits after an extended lateral approach was reported with a percentage of 0-5 % by 88 % of the respondents. Participants stated that especially a poor microcirculation of the foot, disregard of soft tissue conserving techniques, overall condition of the patient, smoking, long time-to-surgery and operation time are the main reasons for wound healing deficits.

CONCLUSION

Given the extended lateral approach as the preferred treatment option, we found minimally invasive techniques and primary arthrodesis of the lower ankle joint play a minor role in treating intra-articular calcaneal fractures in Germany. Ninety percent of our respondents stated less than 5 % of patients required re-operations due to infections and wound healing deficits. Level of Evidence Level V, expert opinion.

Low Genetic Variability in the Highly Endangered Mediterranean Monk Seal

Genetic variability is an important component in the ability of populations to adapt in the face of environmental change. Here we report the first description of nuclear genetic variability in the only remaining sizable colony of the Mediterranean monk seal (Monachus monachus), located at Cap Blanc (Western Sahara, Mauritania), whose estimated size during the study period (1994-May 1997) was about 320 individuals. We tested 42 microsatellite loci isolated from five pinniped species in a sample of 52 pups. Three loci failed to give any product, and of the remaining 39, only 15 were polymorphic, with a maximum of 3 alleles detected. Three loci appeared to be X-linked. No departures from Hardy-Weinberg equilibrium were detected and no genetic structure was found between the two nursing caves currently occupied by the seals. Several analytical methods show that, as a consequence of a severe bottleneck, the population has suffered a decrease in genetic variability over the last few centuries.

Levels of organochlorine compounds in spotted dolphins from the Coiba archipelago, Panama

Blubber and skin samples from 63 spotted dolphins (Stenella attenuata) (18 males, 40 females and 5 of unknown sex) were collected by biopsy techniques in the waters of the Coiba archipelago. Blubber was analyzed for organochlorine compounds and skin for gender determination. Mean levels of HCB (hexachlorobenzene), tPCB (polychlorinated biphenyls) and tDDT (dichlorodiphenyltrichloroethane) were 0.064, 2.30 and 6.4 mgkg(-1), respectively. These levels are low and are not considered to represent a threat to the S. attenuata population. No significant differences either in concentrations of HCB, tPCB and tDDT or in PCB profiles were observed between males and females. The ratio tDDT/tPCB was 2.69, indicating predominantly agrarian versus industrial activities in the area. The ratio ppDDE/tDDT was 0.83, a high figure that suggests both a local reduction of DDT inputs and a high rate of DDT degradation. Significant quantitative and qualitative differences were observed between two schools, suggesting intra-population heterogeneity in organochlorine exposure possibly due to demographic segregation.

Organochlorine compounds in common dolphins (Delphinus delphis) from the Atlantic and Mediterranean waters of Spain

Blubber of free-ranging common dolphins (Delphinus delphis) from the northwestern coast of Spain (Atlantic), sampled in 1984 and 1996, and of common dolphins entangled in fishing nets in the southwestern Mediterranean, sampled during 1992 1994, was analysed for organochlorine pollutants. In the Atlantic, concentration of all pollutants was significantly higher in males than in females. The overall tPCB/tDDT ratio in this area was 3.35, which indicates a predominance of industrial inputs over those associated with agriculture. Individuals sampled in 1996 showed significantly lower DDT concentrations but a higher ppDDE/tDDT ratio than those sampled in 1984, which reflects the aging of the environmental load. In the same period, tPCB concentration remained constant and, as a consequence, the tPCB/tDDT ratio more than doubled. In the Mediterranean, the reduced sample size of adult individuals precluded proper statistical investigation of sex-related variation. The overall tPCB/tDDT ratio was 1.12, suggesting a higher contribution of pollutants of agricultural origin. Individuals had significantly higher levels of all DDT forms and a higher ppDDE/tDDT ratio than their counterparts from the Atlantic, but similar PCB concentrations. However, the relative frequency of the different congeners in relation to the total PCB load was different in the two areas. This indicates that the two populations do not mix, at least in the short- or medium-term. Organochlorine levels in both areas are at the mid to low end of the range of concentrations detected in other common dolphin populations and in that of other Delphinidae species from the same region. Although the impact of the organochlorine concentrations on the common dolphin populations surveyed cannot be assessed, it is considered unlikely that they have played a significant role in the decline that the species has suffered in recent decades in the western Mediterranean.

Biological factors affecting variability of persistent pollutant levels in cetaceans

The main biological factors responsible for the variability of pollutant concentrations in cetaceans are reviewed. Diet is significant because many pollutants are concentrated through food webs. This explains most interspecific differences in pollutant levels and it may also contribute to variation among populations of the same species or even among different components of the same population when diet is subject to age-related or sex-related variations. The effect of body size is complex. Excretion rate and activity of detoxifying enzymes decrease as body weight increases, processes which would lead to higher pollutant concentrations in large animals. In contrast, a high metabolic rate, which is inversely correlated to body size, is associated with high pollutant concentrations. These opposing effects usually result in higher residue levels in smaller individuals. Body composition affects the contribution of each body compartment to the overall pollutant load. Therefore, the body load of lipophilic pollutants will strongly depend on the relative mass of blubber, a variable that shows a threefold variation among cetacean species or, in seasonal feeders, among individuals. Nutritive condition also affects the dynamics of lipophilic pollutants. Lipid mobilisation results in an increase in residue levels, but this variation is not as large as a purely concentrative model would suggest because of enhancement of detoxification processes following a rise in tissue pollutant concentrations. Disease affects pollutant levels in different ways: impoverishing nutritive condition; altering normal physiological functions; and depressing reproduction therefore reducing reproductive transfer in females. The combined result of these processes is usually an increase in pollutant levels in diseased individuals. The concentration of lipophilic pollutants normally increases with age in males because input exceeds the ability of the organism to excrete pollutants. Variable proportions of the pollutant load are transferred to offspring during gestation and lactation, for which reason tissue concentrations in females decrease or stabilise, thus producing lower residue levels than in males. However, because not all compounds are transferred at the same rate, their relative abundance varies with age and sex.Intensity of reproductive transfer is also associated with the reproductive traits of the species, particularly the length of lactation. With the exception of zinc, concentrations of heavy metals increase with age in both sexes but, by contrast with lipophilic pollutants, concentrations in females are similar or higher than in males. The significance of these factors of variation should be taken into account when designing sampling methodology, comparing sample groups, or evaluating toxicological impact.

Heme and the endothelium. Effects of nitric oxide on catalytic iron and heme degradation by heme oxygenase

We studied the effects of nitric oxide (NO) on the control of excess cellular heme and release of catalytically active iron. Endothelial cells (ECs) exposed to hemin followed by a NO donor have a ferritin content that is 16% that of cells exposed to hemin alone. Hemin-treated ECs experience a 3.5-fold rise in non-heme, catalytic iron 2 h later, but a hemin rechallenge 20 h later results in only a 24% increase. The addition of a NO donor after the first hemin exposure prevents this adaptive response, presumably due to effects on ferritin synthesis. NO donors were found to reduce iron release from hemin, while hemin accumulated in cells. A NO donor, in a dose-dependent fashion, inhibited heme oxygenase activity, measured by bilirubin production. Using low temperature EPR spectroscopy, heme oxygenase inhibition correlated with nitrosylation of free heme in microsomes. Nitrosylation of cellular heme prevented iron release, for while there was heme oxygenase-dependent release of iron in cells incubated with hemin for 24 h, the addition of a NO donor blocked iron release. This indicates that NO readily nitrosylates intracellular free heme and prevents its degradation by heme oxygenase. Nitrosylation of heme was found to reduce sensitization of cells to oxidative injury.