Biomechanical evaluation of two innovative locking implants for comminuted olecranon fractures under high-cycle loading conditions

"Mother and baby plate": a strategy to improve stability in proximal fractures of the ulna

INTRODUCTION

Proximal ulna fractures with a large zone of comminution, such as in the context of Monteggia injuries, require mechanically strong osteosyntheses as they occur in regions with high physiological joint load. Consequently, implant failure and pseudarthrosis are critical and devastating complications, especially with the background of mainly young patients being affected. An effective solution could be provided by adding a small second plate 90° angulated to the standard dorsal plate in the area of non-union. Thus, this study investigates whether, from a biomechanical point of view, the use of such a mini or baby plate is worthwhile.

MATERIALS AND METHODS

Comminuted fractures distal to the coronoid process, equivalent to Jupiter type IIb fractures, are generated on artificial Sawbones® of the ulna and stabilized using two different plate osteosyntheses: in the first group, a dorsal locking compression olecranon plate is used (LCP group). In the second group, a small, ulnar 5-hole olecranon plate is added as a baby plate in addition to the mother plate at the level of the fracture zone (MBP group). Dynamic biomechanical loading in degrees of flexion from 0° to 90° is carried out to determine yield load, stiffness, displacement, and changes in fracture gap width as well as bending of the dorsal plate.

RESULTS

The "mother-baby-plate" osteosynthesis had a significantly higher yield load (p < 0.01) and stiffness (p = 0.01) than the LCP group. This correlates with the increased movement of the proximal fracture element during cyclic testing for the LCP group compared to the MBP group as measured by an optical metrology system.

CONCLUSIONS

Here, we show evidence that the addition of a small plate to the standard plate is highly effective in increasing the biomechanical stability in severe fractures equivalent to Jupiter type IIb. As it hopefully minimizes complications like pseudarthrosis and implant failure and as the additional preparatory effort leading to compromised blood supply is regarded to be negligible, this justifies and highly advises the use of a mother-baby-plate system.

Biomechanics of plate fixation following traditional olecranon osteotomy versus novel proximal ulna osteotomy for visualizing a distal humerus injury

After a distal humeral injury, olecranon osteotomy (OO) is a traditional way to visualize the distal humerus for performing fracture fixation. In contrast, the current authors previously showed that novel proximal ulna osteotomy (PUO) allows better access to the distal humerus without ligamentous compromise. Therefore, this study biomechanically compared plating repair following OO versus PUO. The left or right ulna from eight matched pairs of human cadaveric elbows were randomly assigned to receive OO or PUO and repaired using pre-contoured titanium plates. Destructive and non-destructive mechanical tests were performed to assess stability. Mechanical tests on OO versus PUO groups yielded average results for ulna cantilever bending stiffness at a 90° elbow angle (29.6 vs 30.5 N/mm, p = 0.742), triceps tendon pull stiffness at a 90° elbow angle (28.2 vs 24.4 N/mm, p = 0.051), triceps tendon pull stiffness at a 110° elbow angle (61.9 vs 59.5 N/mm, p = 0.640), and triceps tendon pull failure load at a 110° elbow angle (1070.1 vs 1359.7 N, p = 0.078). OO and PUO elbows had similar failure mechanisms, namely, tendon tear or avulsion from the ulna with or without some fracture of the proximal bone fragment, or complete avulsion of the proximal bone fragment from the plate. The similar biomechanical stability (i.e., no statistical difference for 4 of 4 mechanical measurements) and failure mechanisms of OO and PUO plated elbows support the clinical use of PUO as a possible alternative to OO for visualizing the distal humerus.

Olecranon Fractures: A Critical Analysis Review

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Olecranon fractures account for 10% of all elbow fractures and are more likely to result from a low-energy injury. A displaced fracture with a stable ulnohumeral joint (Mayo type 2) is the most common type of injury.

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The management of an isolated olecranon fracture is based on patient factors (age, functional demand, and if medically fit to undergo surgery) and fracture characteristics including displacement, fragmentation, and elbow stability.

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Nonoperative management can be successfully used in undisplaced fractures (Mayo type 1) and in displaced fractures (Mayo type 2) in frail patients with lower functional demands.

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Patients with displaced olecranon fractures with a stable ulnohumeral joint without significant articular surface fragmentation (Mayo type 2A) can be managed with tension band wiring, plate osteosynthesis (PO), intramedullary fixation, or suture repair.

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PO is advocated for multifragmentary fractures and fractures that are associated with ulnohumeral instability. It is essential to consider the variable anatomy of the proximal ulna during surgery.

Efficacy and safety of tension band wire versus plate for Mayo II olecranon fractures: a systematic review and meta-analysis

Purpose

For olecranon fractures, the choice of tension band wire (TBW) or plate fixation has long been controversial. Therefore, this study aimed to evaluate the efficacy and safety of TBW and plate in the treatment of patients with Mayo II olecranon fractures by Meta-analysis.

Methods

PubMed, Embase, Cochrane, the Web of Science, China National Knowledge Infrastructure, Wanfang, and China Biomedical Database were searched for randomized controlled trials (RCTs) and cohort studies (CSs) where TBW was compared with plate for Mayo II olecranon fractures (OF). Subsequently, the data were extracted by two reviewers independently and were analysed via RevMan5.4.1. Besides, mean difference (MD), risk ratio (RR), and 95% confidence intervals (CIs) were calculated. Furthermore, Cochrane Risk of Bias Tool 2.0 and Newcastle–Ottawa Scale were adopted for assessing the risk of bias.

Results

A total of 1RCT and 10 CSs were included, when 449 cases were treated with TBW and 378 with plate. The plate has favourable postoperative long-term (≥ 1 year) functional score in MEPS (MD: − 3.06; 95% CI − 5.50 to 0.62; P = 0.01; I² = 41%) and Dash score (MD: 2.32; 95% CI 1.91, 2.73; P < 0.00001; I² = 0%), also carrying fewer complications (RR: 2.13; 95% CI 1.48, 3.08; P < 0.0001; I² = 58%). Besides, there exists no significant difference in postoperative long-term (≥ 1 year) elbow flexion (MD: − 1.82°; 95% CI − 8.54, 4.90; P = 0.60; I² = 71%) and extension deficits (MD: 1.52°; 95% CI − 0.38, 3.42; P = 0.12; I² = 92%). Moreover, TBW is featured with a shorter operation time (MD = − 5.87 min; 95% CI − 7.93, − 3.82; P < 0.00001; I² = 0) and less intraoperative bleeding (MD: − 5.33 ml; 95% CI − 8.15, − 2.52; P = 0.0002; I² = 0). In terms of fracture healing time, it is still controversial. Furthermore, the subgroup analysis has revealed that for Mayo IIA OF, the plate has a better outcome in the long-term (≥ 1 year) postoperative MEPS, the Dash score, and the incidence of postoperative complications than TBW, while there is no significant difference in the long-term (≥ 1 year) postoperative elbow motion between two groups.

Conclusions

Plate has better efficacy and safety for Mayo II OF. Considering that few studies are included in the meta-analysis, more high-quality RCTs are still required to confirm these findings.

PROSPERO registration number: CRD42022313855.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03262-7.

Lag screw osteosynthesis of simple olecranon fractures: A biomechanical comparative study

Olecranon fractures are most frequently stabilized by tension band wiring (TBW), which unfortunately leads to relevant implant removal rates due to K-wire migration and soft tissue irritation. As lag screw osteosynthesis (LSO) might be a gentle and effective alternative in simple fracture patterns, the goal of the present study was to biomechanically compare LSO with TBW in simple olecranon fractures at a cadaver model. A simple olecranon fracture (Mayo type IIA) was created in eight pairs of human cadaver elbows, which were pairwise fixed by either TBW or two transcortical 4.0 mm lag screws. Biomechanical testing was conducted as a pulling force, applied to the triceps tendon in a 90° position. First, cyclic loading between 10 and 300 N was performed for 50,000 cycles. Afterward, maximum load was raised by 0.02 N/cycle until construct failure, what was defined as displacement >2 mm. Besides fracture displacement, failure cycle and failure load, the modes of failure were analyzed. Within the first five cycles, there was no significant difference in displacement (median TBW: 0.2 mm; LSO: 0.5 mm; p = 0.091). Both after 2000 (median TBW: 0.2 mm; LSO: 0.6 mm; p = 0.042) and after 20,000 cycles (median TBW: 0.4 mm; LSO: 0.9 mm; p = 0.027), the difference was significant. Failure cycle (median TBW: 72,639 cycles; LSO: 43,429 cycles; p = 0.017) and failure load (median TBW: 702 N; LSO: 303 N; p = 0.025) differed significantly as well. TBW mostly (6/8) failed at the lock of the cerclage wire, whereas most LSO constructs (5/8) failed as a pullout of the proximal fragment. In conclusion, to our biomechanical findings at human cadaver specimens, simple olecranon fractures treated by LSO show higher dislocation rates and lower failure loads compared to conventional TBW and mostly fail by pullout of the proximal fragment.

Biomechanical comparisons of hook plate and screw fixations in split-type greater tuberosity fractures of the humerus

BACKGROUND

Screws and plate are commonly utilized for the fixation of split-type humeral greater tuberosity (GT) fractures. However, the mechanical properties of these 2 types of fixation methods have not been compared directly. The aim of the present study was to evaluate the classic 2 screws fixation with hook locking plate from a mechanical perspective.

METHODS

Sixteen synthetic humerii (Sawbones Pacific Research Laboratories, Vashon, WA, USA) were divided into 2 groups. An osteotomy was performed to simulate a split-type GT fracture. Group A (n = 8) was fixed with 2 standard parallel screws. Group B (n = 8) was fixed with a hook plate. Each specimen was tested with traction force at 45° shoulder abduction. Following the 20-N preload, a 500-cycle loading test was applied with a force ranging from 20 to 200 N (valley/peak), and the interfragmental displacement was measured periodically at intervals of 100 cycles. Finally, all the specimens were pulled with destructive force at a rate of 5 mm/min until catastrophic failure.

RESULTS

The hook plate exhibited greater construct stiffness than the screw fixation (63.2 ± 6.1 N/mm vs. 40.9 ± 3.4 N/mm, P < .001). All of the specimens completed the entire cyclic loading test without catastrophic failure, and the fragment displacement after 500 cycles was 0.4 ± 0.2 mm for the hook plate and 2.1 ± 0.3 mm for screw fixation, which was statistically lower in the plate group (P < .001). In terms of failure load, the hook plate group exhibited a significantly greater value than the screw group (770.6 ± 94.6 vs. 427.5 ± 45.1 N/mm, P < .001). The failure modes of both fixation methods were distinct.

CONCLUSION

In humeral GT fracture fixation, hook plate fixation appears to offer greater construct stiffness and failure load while maintaining fragment stability to resist a physiological traction force. The current study provides support from a mechanical perspective for the clinical application of the hook plate.

Open Reduction and Stable Internal Fixation Using a 3.5-mm Locking Hook Plate for Isolated Fractures of the Greater Tuberosity of the Humerus: A 2-Year Follow-up Study Using an Innovative Fixation Method

Backgroud

The best treatment for isolated greater tuberosity (GT) fractures is still controversial. Although previous studies have suggested surgical options, they are either unable to provide firm fixation or present with a variety of complications.

Methods

We retrospectively studied the records of patients with isolated GT fractures who underwent open reduction and internal fixation using a 3.5-mm locking hook plate between January 2016 and January 2018. The surgical indication was an at least 5-mm displacement of the GT as observed in either simple radiography or three-dimensional computed tomography. Clinical outcomes were assessed using the following five parameters shortly before implant removal and at the final follow-up: visual analog scale (VAS) pain score, American Shoulder and Elbow Surgeons (ASES) score, Shoulder Rating Scale of the University of California, Los Angeles (UCLA), Constant-Murley score, and range of motion.

Results

Twenty-one patients with a mean age of 64 years were included. Bone union was achieved within 12–20 weeks of the first surgery in all patients. Implant removal was performed between 13 and 22 weeks after surgery. At the final follow-up, the mean VAS pain score, forward flexion, abduction, external rotation, internal rotation, ASES score, UCLA score, and Constant-Murley score were significantly better when compared to outcomes shortly before implant removal (p < 0.001, p < 0.001, p < 0.001, p = 0.008, p = 0.003, p < 0.001, p < 0.001, and p < 0.001, respectively).

Conclusions

The 3.5-mm locking hook plate provided sufficient stability and led to satisfactory clinical and radiological outcomes for isolated GT fractures. However, the hook plate may irritate the rotator cuff, and postoperative stiffness may be inevitable. Therefore, second surgery for implant removal is necessary after bone union is achieved.

Low-profile double plating of unstable osteoporotic olecranon fractures: a biomechanical comparative study

BACKGROUND

In the treatment of unstable olecranon fractures, anatomically preshaped locking plates exhibit superior biomechanical results compared with tension band wiring. However, posterior plating (PP) still is accompanied by high rates of plate removal because of soft-tissue irritation and discomfort. Meanwhile, low-profile plates precontoured for collateral double plating (DP) are available and enable muscular soft-tissue coverage combined with angular-stable fixation. The goal of this study was to biomechanically compare PP with collateral DP for osteosynthesis of unstable osteoporotic fractures.

METHODS

A comminuted displaced Mayo type IIB fracture was created in 8 osteoporotic pairs of fresh-frozen human cadaveric elbows. Pair-wise angular stable fixation was performed by either collateral DP or PP. Biomechanical testing was conducted as a pulling force to the triceps tendon in 90° of elbow flexion. Cyclical load changes between 10 and 300 N were applied at 4 Hz for 50,000 cycles. Afterward, the maximum load was raised by 0.02 N/cycle until construct failure, which was defined as displacement > 2 mm. Besides failure cycles and failure loads, modes of failure were analyzed.

RESULTS

Following DP, a median endurance of 65,370 cycles (range, 2-83,121 cycles) was recorded, which showed no significant difference compared with PP, with 69,311 cycles (range, 150-81,938 cycles) (P = .263). Failure load showed comparable results as well, with 601 N (range, 300-949 N) after DP and 663 N (range, 300-933 N) after PP (P = .237). All PP constructs and 3 of 8 DP constructs failed by proximal fragment cutout, whereas 5 of 8 DP constructs failed by bony triceps avulsion.

CONCLUSION

Angular-stable DP showed comparable biomechanical stability to PP in unstable osteoporotic olecranon fractures under high-cycle loading conditions. Failure due to bony triceps avulsion following DP requires further clinical and biomechanical investigation, for example, on suture augmentation or different screw configurations.

Outcome after polyaxial locking plate osteosynthesis in proximal tibia fractures: a prospective clinical trial

Background

The aim of this study was to evaluate the clinical and/or radiologic outcome using different polyaxial locking plates for the treatment of proximal tibia fractures, the Non-Contact-Briding plate (NCB-PT®) by Zimmer or the Variable Angle Locking Compression Plate (VA-LCP®) by Synthes.

Methods

This study enrolled 28 patients with proximal tibia fractures (AO/ OTA 41 B-C) and indication for locking plate osteosynthesis. All patients were treated with a polyaxial locking plate system. Depending on the fracture morphology, patients were either treated with a NCB-PT® or VA-LCP®. The implant was chosen according to the surgeon’s experience and preference, in case of a higher degree of comminution the tendency was observed to use the NCB-PT® plate. After a time interval of 12 months postoperative we conducted clinical (e.g. range of motion, the Rasmussen score) and radiological (e.g. primary/secondary loss of reduction) follow-ups.

Results

Patients provided with the NCB-PT® (9 patients) showed longer operation time, use of longer implants, longer interval from injury to surgery and lower clinical scores after the 12 months follow-up compared with the VA-LCP® group (19 patients). Interestingly, the results showed no significant differences regarding the clinical and radiologic outcome.

Conclusions

The small number of patients as well as the heterogeneity of fractures constitute a limitation of this study. Nevertheless, the differentiated use of implants is associated with comparable clinical and radiological outcomes. This trial emphasizes the need for further prospective randomised trials with higher patient numbers.

Trial registration

Retrospectively registered 21.12.2020. Registration number NCT04680247.

Low-profile double plating versus dorsal LCP in stabilization of the olecranon fractures

INTRODUCTION

Proximal ulna fractures are common in orthopaedic surgery. Comminuted fractures require a high primary stability by the osteosynthesis, to allow an early functional rehabilitation as fast as possible, to reduce long-term limitations of range of motion. Classical dorsal plating is related to wound healing problems due to the prominence of the implant. New low-profile double plates are available addressing the soft tissue problems by positioning the plates at the medial and lateral side. This study analysed whether, under high loading conditions, these new double plates provide an equivalent stability as compared to the rigid olecranon locking compression plate (LCP).

MATERIALS AND METHODS

In Sawbones, Mayo Type IIB fractures were simulated and stabilized by plate osteosyntheses: In group one, two low-profile plates were placed. In group two, a single dorsal plate (LCP) was used. The bones was than cyclically loaded simulating flexion grades of 0°, 30°, 60° and 90° of the elbow joint with increasing tension forces (150 , 150 , 300  and 500 N). The displacement and fracture gap movement were recorded. In the end, in load-to-failure tests, load at failure and mode of failure were determined.

RESULTS

No significant differences were found for the displacement and fracture gap widening during cyclic loading. Under maximum loading, the double plates revealed a comparable load at failure like the single dorsal plate (LCP). The double plates failed with a proximal screw pull-out of the plate, whereas in the LCP group, in 10 out of 12 specimens the mode of failure was a diaphyseal shaft fracture at the distal plate peak.

CONCLUSION

Biomechanically, the double plates are a good alternative to the dorsal LCP providing a high stability under high loading conditions and, at the same, time reducing the soft tissue irritation by a lateral plate position.

Surgical treatment of posterior cruciate ligament tibial avulsion fractures using a locking compression hook plate: A case series

OBJECTIVE

This study aimed to evaluate the results of surgical treatment of tibial avulsion injuries of the posterior cruciate ligament (PCL) with a 3.5-mm locking compression hook plate (LCHP).

METHODS

From June 2012 to June 2015, 16 consecutive patients (10 males and 6 females, mean age: 38 (range: 19-57) years) presented with isolated tibial avulsion injuries of the PCL. We used a 3.5-mm LCHP and lag screws for open reduction and internal fixation (ORIF) through the posterior medial approach. The operation time, quantity of bleeding, visual analog scale (VAS) scores, stability of posterior drawer test (PDT) results, and fracture healing time were studied to assess clinical efficacy. At the 12-month follow-up, a functional evaluation using knee range of motion (ROM) and the Lysholm knee scoring system (LKSS) was performed.

RESULTS

The data from a mean follow-up of 24.1 (range: 14-33) months from 16 patients were recorded. No neurovascular complications, incision infections, or delayed union or nonunion were observed. The mean operation time was 61.4 (range: 45-80) min. The mean quantity of bleeding was 41.6 (range: 25-66) mL. The mean bone healing time was 11.8 (range: 45-80) weeks. The mean VAS score was 1.63 (range: 0-3) after surgery. The average LKSS and ROM of the knee were 51.75±7.67 and 50.94°±10.19° before surgery and 92.75±5.46 and 127.75°±6.13° at 1 year, respectively. The outcomes were judged to be excellent for 11 patients, good for 4, and fair for 1 (excellent and good rates: 93.8% for 15/16). At the final follow-up (≥1 year), the PDT scores returned to normal.

CONCLUSION

The results showed that 3.5-mm LCHP provided reliable fixation following ORIF of isolated PCL tibial avulsion fractures and was a safe, simple, and effective procedure. This procedure may reduce complications and improve functional recovery relative to those of other procedures.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR-1900022920. Registered on 3 May 2019.

LEVEL OF EVIDENCE

Level IV, Therapeutic study.

Nailing vs. plating in comminuted proximal ulna fractures - a biomechanical analysis

Background

Comminuted proximal ulna fractures are severe injuries with a high degree of instability. These injuries require surgical treatment, usually angular stable plating or double plating is performed. Nailing of proximal ulna fracture is described but not performed regularly. The aim of this study was to compare a newly developed, locked proximal ulna nail with an angular stable plate in an unstable fracture of the proximal ulna. We hypothesize, that locked nailing of the proximal ulna will provide non-inferior stability compared to locked plating.

Methods

A defect fracture distal to the coronoid was simulated in 20 sawbones. After nailing or plate osteosynthesis the constructs were tested in a servo-pneumatic testing machine under physiological joint motion (0°-90°) and cyclic loading (30 N – 300 N). Intercyclic osteotomy gap motion and plastic deformation of the constructs were analyzed using micromotion video-analysis.

Results

The locked nail showed lower osteotomy gap motion (0.50 ± 0.15 mm) compared to the angular stable plate (1.57 ± 0.37 mm, p < 0.001). At the anterior cortex the plastic deformation of the constructs was significantly lower for the locked nail (0.09 ± 0.17 mm vs. 0.39 ± 0.27 mm, p = 0.003). No statistically significant differences were observed at the posterior cortex for both parameters.

Conclusions

Nail osteosynthesis in comminuted proximal ulna fractures shows lower osteotomy gap motion and lower amount of plastic deformation compared to locking plate osteosynthesis under laboratory conditions.

Biomechanical comparison of biodegradable magnesium screws and titanium screws for operative stabilization of displaced capitellar fractures

BACKGROUND

Displaced fractures of the humeral capitellum are commonly treated operatively and fixed by titanium screws (TSs) either directly or indirectly. In the case of direct transcartilaginous fixation, biodegradable screws with the ability to be countersunk can be favorable regarding implant impingement and cartilage destruction. Hence, the goal of this study was to biomechanically compare headless compression screws made from titanium with a biodegradable equivalent made from a magnesium alloy.

METHODS

This biomechanical in vitro study was conducted on 13 pairs of fresh-frozen human cadaveric humeri, in which a standardized Bryan-Morrey type I fracture was fixed using 2 magnesium screws (MSs) or 2 TSs. First, construct stiffness was measured during 10 cycles of static loading between 10 and 50 N. Second, continuous loading was applied at 4 Hz between 10 and 50 N, increasing the maximum load every 10,000 cycles by 25 N until construct failure occurred. This was defined by fragment displacement >3 mm.

RESULTS

Comparison of the 2 screw types showed no differences related to construct stiffness (0.50 ± 0.25 kN/mm in MS group and 0.47 ± 0.13 kN/mm in TS group, P = .701), failure cycle (43,944 ± 21,625 and 41,202 ± 16,457, respectively; P = .701), and load to failure (152 ± 53 N and 150 ± 42 N, respectively; P = .915).

CONCLUSION

Biomechanical comparison showed that simple capitellar fractures are equally stabilized by headless compression screws made from titanium or a biodegradable magnesium alloy. Therefore, in view of the advantages of biodegradable implants for transcartilaginous fracture stabilization, their clinical application should be considered and evaluated.

Biomechanical comparison of a 3.5 mm anterior locking plate to cannulated screws with anterior tension band wiring in comminuted patellar fractures

PURPOSE

To date, surgically treated multifragmentary patellar fractures are still associated with high rates of complications, such as i.e. secondary fracture displacement. Osteosynthesis is most frequently performed with screws and cerclages. To increase primary stability, locking plates have been introduced. However, there is still a lack of biomechanical data supporting the superiority of plate fixation compared to screw fixation with cerclages in these cases. The goal of the present study was to conduct biomechanical comparison of these two techniques under dynamic loading conditions.

METHODS

A standardized 34-C3 fracture was created in eight pairs of human cadaveric knee joints. Following a randomization protocol, they were fixed with a 3.5 mm anterior locking plate (LP) or cannulated screws with anterior tension band wiring (hybrid osteosynthesis, HO).Subsequently, all constructs were tested for 100 cycles from 90° of knee-flexion to full extension by applying a pulling force to the quadriceps tendon. Outcome parameters were fracture displacement after one cycle, after 100 cycles and implant loosening. Failure was defined as fracture displacement > 2 mm.

RESULTS

Biomechanical testing showed significantly less fracture displacement following LP compared to HO both after the first (p = 0.042) and after 100 cycles (p = 0.025). The difference in loosening was significant as well (p = 0.017). Following HO, 5/8 constructs failed during cyclic loading. There was no failure in the LP group. In the HO group, loosening correlated with bone mineral density (R = - 0.857) which was not observed in the LP group (R = - 0.429).

CONCLUSION

Anterior locking plate osteosynthesis of comminuted patellar fractures biomechanically provides better primary stability compared to cannulated screws with anterior tension band wiring.

Nailing of proximal ulna fractures: biomechanical comparison of a new locked nail with angular stable plating

PURPOSE

Proximal ulna fractures are common injuries and frequently treated with angular stable plating. This surgical option shows good functional results. Relevant drawbacks such as large soft tissue exposure, compromised blood supply of fracture fragments and disturbing osteosynthetic material are described. The aim of this study was to compare a new locked proximal ulna nail with angular stable plating in a biomechanical testing setup for extraarticular proximal ulna fractures.

METHODS

Ten pairs of sawbones with a Jupiter type IIB proximal ulna fracture (OTA 2U1A3.1) were tested after osteosynthesis with the mentioned implants in a servo-pneumatic testing machine. The testing setup simulates physiological joint motion (0°-90°) under cyclic loading (30-300 N). Primary stability and loosening of both constructs were quantified using micromotion video-analysis after 608 test cycles.

RESULTS

The micromotion analysis showed significantly higher primary stability of the locked nail (0.29 ± 0.13 mm) compared to the angular stable plate (0.97 ± 0.30 mm, p < 0.001). Both implants showed a low amount of loosening after completion of the test cycles. The construct with the locked nail (0.08 ± 0.06 mm) showed significantly lower dislocation of the fragments measured at the anterior cortex (plate 0.24 ± 0.13 mm, p < 0.001).

CONCLUSION

Nailing of proximal ulna fractures shows significantly higher primary stability and lower loosening compared to angular stable plating in our testing setup.

Plate fixation and tension band wiring after isolated olecranon fracture comparison of outcome and complications

Objective

Olecranon fractures are common injuries in patients of any age. The vast majority are treated with two operation techniques: a plate fixation (PF) or tension band wiring (TBW). The objective of this study is to compare the outcomes of surgically treated olecranon fractures with plate fixation or tension band wiring. We hypothesise that PF patients would show significantly inferior outcomes due to more complex injuries.

Patients and methods

Between 2010 and 2017, a total of 108 patients were treated with plate fixation and or tension band wiring. Clinical data of 40 surgically treated olecranon fractures were collected and analysed. Clinical and functional evaluations were performed using Mayo-Score, DASH-Score, Weseley -Score and subject elbow value (SEV). Furthermore, complication rates, time to return to work and operation duration were documented.

Results

The mean follow-up was 70.5 ± 45.6 months. Time of return to work was 6.5 ± 2.2 weeks in the TBW group and 10.9 ± 6,6 in the PF group (p = 0.372). The mean duration of surgery was 95.2 ± 47.0 min in the TBW group and 192.5 ± 113.0 min in the PF group (p = 0.001). In the TBW group, the mean hospitalisation period was 7.9 ± 10.1 days and 11.2 ± 9.8 days in the PF group. Revisions were required in 0.3 ± 0.6 of cases (0.2 ± 0.5 in TBE and 0.4 ± 0.7 in PF). The median DASH Score was 7.0 (3.6-13.7) in the TBW group and 12.1 (5.5-24.8) in the PF group (p = 0.948).

Conclusion

Tension band wiring and plate fixation are both practical treatment options with mostly positive outcomes, even though high complication rates can occur. There were no significant differences in either group concerning functional outcome or time back to work. The duration of surgery was significantly higher in the PF group, whereas the incidence of metalwork-associated complications was higher in the TBW group.

Biomechanical Evaluation of Standard Versus Extended Proximal Fixation Olecranon Plates for Fixation of Olecranon Fractures

Background: Small olecranon fractures present a significant challenge for fixation, which has resulted in development of plates with proximal extension. Olecranon-specific plates with proximal extensions are widely thought to offer superior fixation of small proximal fragments but have distinct disadvantages: larger dissection, increased hardware prominence, and the increased possibility of impingement. Previous biomechanical studies of olecranon fracture fixation have compared methods of fracture fixation, but to date there have been no studies defining olecranon plate fixation strength for standard versus extended olecranon plates. The purpose of this study is to evaluate the biomechanical utility of the extended plate for treatment of olecranon fractures. Methods: Sixteen matched pairs of fresh-frozen human cadaveric elbows were used. Of the 16, 8 matched pairs received a transverse osteotomy including 25% and 8 including 50% of the articular surface on the proximal fragment. One elbow from each pair was randomly assigned to a standard-length plate, and the other elbow in the pair received the extended-length plate, for fixation of the fracture. The ulnae were cyclically loaded and subsequently loaded to failure, with ultimate load, number of cycles, and gap formation recorded. Results: There was no statistically significant difference between the standard and extended fixation plates in simple transverse fractures at either 25% or 50% from the proximal most portion of the articular surface of the olecranon. Conclusion: Standard fixation plates are sufficient for the fixation of small transverse fractures, but caution should be utilized particularly with comminution and nontransverse fracture patterns.

Use of an Additional Nonlocking Screw in Olecranon Fracture Osteosynthesis Changes Failure Mechanism

Hardware-related complications can occur when plate fixation is used to stabilize osteoporotic fractures involving the olecranon. The use of an additional nonlocking screw, placed retrograde into the proximal fracture segment, may improve stability under load. The purpose of this study was to conduct a biomechanical comparison of olecranon repair constructs with and without this additional retrograde screw. Nine matched pairs of elderly fresh-frozen cadaveric upper extremities were used. Two-part olecranon fractures were modeled, and fracture stabilization was performed. Olecranon plates were implanted either with the standard surgical technique (CTRL) or with an additional retrograde screw (EXPT). Dynamic extensions of increasingly loaded forearms were performed, and comparisons of sustained cycles, maximum load, and total work were made. Relative motion of bone segments was tracked, and modes of failure were assessed. Seventy-eight percent of specimens from the CTRL group failed due to relative fragment displacement exceeding 3 mm, while 78% of EXPT specimens failed due to instantaneous catastrophic failure. There were no significant differences in terms of number of survived cycles, maximum load, or work performed between the groups. The addition of a retrograde screw in this plating technique changes the failure mode from fracture displacement to catastrophic failure. The use of a 3.5-mm retrograde screw in the relatively small proximal ulnar fragment should be avoided, but screws with a smaller diameter may still have potential to improve fixation. Further biomechanical and clinical research is necessary to improve strategies for plate fixation of olecranon fractures in the elderly population. [Orthopedics. 2019; 42(1):e74-e80.].

Excellent results and low complication rate for anatomic polyaxial locking plates in comminuted proximal ulna fractures

BACKGROUND

Comminuted fractures of the proximal ulna remain a great challenge in orthopedic surgery. The purpose of this study was to report the outcomes of comminuted proximal ulna fractures treated with a new construct type-anatomically preformed polyaxial locking compression plates.

METHODS

Between 2013 and 2016, 46 patients with isolated comminuted fractures were treated with a 2.7-/3.5-mm VA-LCP Olecranon Plate (Synthes, Umkirch, Germany). Of these, 44 were available for an assessment after a mean follow-up period of 2.5 years (range, 12-50 months). We evaluated range of motion, time to recovery, revision rate, and indications, as well as functional scores. Radiographs were analyzed.

RESULTS

The study included 8 Mayo IB, 29 Mayo IIB, and 7 Mayo IIIB fractures. All fractures showed bony union, and only 2 revision surgical procedures were performed because of a new trauma. No other complications occurred. Mean range of motion was 139° (range, 105°-150°), and the mean pain level was less than 1 on a visual analog scale. Regarding elbow function, we found a mean Mayo Elbow Performance Score of 98; a mean Oxford Elbow Score of 44; and a mean Disabilities of the Arm, Shoulder and Hand score of 6. Of the plates, 41% were removed after an average time of 16 months, whereby a significant improvement in extension deficit was detected (P < .01). Ninety-five percent of all patients returned to their pretrauma sports level.

CONCLUSION

The 2.7-/3.5-mm VA-LCP Olecranon Plate represents an effective option with excellent fracture reduction, sufficient stability for early postoperative functional rehabilitation, and a minimum of complications.

Modulation of cartilage's response to injury: Can chondrocyte apoptosis be reversed?

Osteoarthritis is characterized by a chronic, progressive and irreversible degradation of the articular cartilage associated with joint inflammation and a reparative bone response. More than 100 million people are affected by this condition worldwide with significant health and welfare costs. Our available treatment options in osteoarthritis are extremely limited. Chondral or osteochondral grafts have shown some promising results but joint replacement surgery is by far the most common therapeutic approach. The difficulty lies on the limited regeneration capacity of the articular cartilage, poor blood supply and the paucity of resident progenitor stem cells. In addition, our poor understanding of the molecular signalling pathways involved in the senescence and apoptosis of chondrocytes is a major factor restricting further progress in the area. This review focuses on molecules and approaches that can be implemented to delay or even rescue chondrocyte apoptosis. Ways of modulating the physiologic response to trauma preventing chondrocyte death are proposed. The use of several cytokines, growth factors and advances made in altering several of the degenerative genetic pathways involved in chondrocyte apoptosis and degradation are also presented. The suggested approaches can help clinicians to improve cartilage tissue regeneration.

Floating elbow in a polytrauma patient: timing and surgical strategy

A 22-year-old man was admitted to our hospital because of polytrauma following a car accident. The instrumental investigations detected parenchymatous and bone lesions, including a floating elbow (articular distal humerus fracture associated with ipsilateral forearm fracture). After initial temporary stabilization with external fixator and restoration of hemodynamics, we proceeded to the fixation of the upper limb. To reduce local and general risks of complications, a two-stage reconstruction technique has been applied.