Comparative study of mechanical performance of various fixation constructs in multifragmentary distal humeral shaft fracture: a finite element analysis

BACKGROUND

There has been no scientific mechanical assessment demonstrating the optimal fixation technique in multifragmentary fractures of the distal humeral shaft. The purpose of the present study was to compare the biomechanical performance of 5 fixation constructs as used in minimally invasive plating osteosynthesis (MIPO) for distal humeral shaft fractures.

METHODS

Three-dimensional (3D) humerus model with 20 mm distal humeral shaft fracture gap simulating multifragmentary fracture was created from computed tomography data and virtually fixed by 5 fixation techniques as MIPO, i.e., anterior narrow dynamic compression plate (DCP), anterior narrow locking compression plate (LCP), anterior reversed proximal humeral internal locking system (R-PHILOS), extra-articular distal humerus locking compression plate (LCP-EADH), and anteromedial LCP. All constructs were biomechanically tested under 6 loading conditions by means of finite element analysis, i.e., 250-N axial compression, 7.5-N m internal rotation, 7.5-N m external rotation, 10-N m posterior bending, 10-N m valgus rotation, and 10-N m varus rotation. In addition, A 3D model of each construct was fabricated as 3D printed models. Fixations were applied to the 3D printing model which were later mechanically tested to validate the FE results.

RESULTS

EQV stress exhibited on anterior narrow LCP and anterior R-PHILOS were comparable which were lower than other constructs under axial compression and valgus-varus bending. Anterior R-PHILOS produced lower EQV stress than other constructs under internal-external rotation and posterior bending. On the whole, R-PHILOS demonstrated a comparable fracture displacement to those LCP with anterior or anteromedial approaches, that achieved the lowest displacement values. In addition, the experimental mechanical test values shared a correlation with the FE model results.

CONCLUSION

Overall, the anterior R-PHILOS was considered as a potential candidate for multifragmentary distal humeral shaft fractures. It demonstrated efficacious biomechanical performance in terms of implant stress and distal fragment displacement.

The application of inverted lateral clavicle locking compression plate for medial clavicle fractures: biomechanical study and clinical implementation

BACKGROUND

There has been no absolute consensus on the optimal implant for fixation of medial clavicle fracture. The purpose of the present study was to test the biomechanical efficacy of inverted lateral clavicle locking compression plate (LCP-LC) in fixation of this specific fracture location by finite element analysis.

METHODS

Transverse and comminuted medial clavicle fracture simulated models stabilized by three different devices including inverted LCP-LC, superior clavicle LCP (LCP-SC), and dual reconstruction (LCP-RP) with LCP-SC were investigated biomechanical performance under three loading conditions, i.e., axial compression, inferior bending, and axial torsion.

RESULTS

EQV stress exhibited on implant and elastic strain at fracture site under inferior bending was greater than other loading cases. LCP-SC construct represented the greatest EQV stress and elastic strain. The inverted LCP-LC construct demonstrated lower EQV stress than the LCP-SC construct and was comparable to dual plating. Under axial compression and axial torsion, elastic strain produced from the inverted LCP-LC construct was comparable to dual plating, but greater than dual plating when subjected to inferior bending.

CONCLUSION

By the results of FE analysis, inverted LCP-LC could be a potential application for fixation of clavicle fracture with short medial fragment.

Nonvascularized fibular graft with locking screw fixation for metaphyseal bone loss of distal femur: biomechanical assessment validated by a clinical case series

BACKGROUND

The optimal modality to surgically treat significant bone loss of distal femur remains inconclusive. The objectives of the present study were to assess the mechanical performance of nonvascularized fibular graft (NVFG) with locking screw fixation in distal femur fixation construct by finite element analysis and to retrospectively describe the outcomes of the present technique in clinical cases.

METHODS

Four constructs which the fractured femur was stabilized by LCP-DF alone, dual plating, LCP-DF combined with NVFG, and LCP-DF combined with NVFG (LCP-DF-NVFG-S) with locking screw were assessed the biomechanical performance under physiological loads. For the clinical case series, 12 patients with open intercondylar fracture with metaphyseal bone loss of distal femur were operated by LCP-DF-NVFG-S. The collected data included fracture consolidation, length of NVFG, perioperative complications and objective clinical results.

RESULTS

LCP-DF-NVFG-S demonstrated lower implant equivalent von Mises stress (EQV) stress and better fracture stability than other constructs. A locking screw presented its essence in maintaining the NVFG in the required position and subsequently enhancing the fracture stability. In regard to the clinical series, all fractures were consolidated with an average duration of 27.8 weeks (range 20-32). An average NVFG length was 7.8 cm (range 6-12). No perioperative complication was demonstrated. By the Knee Society score, 1 was considered to be excellent, 9 to be good and 2 to be poor.

CONCLUSION

Based on the results of mechanical assessment and case series, LCP-DF-NVFG-S can be an effective technique in the management of metaphyseal bone loss of distal femur.

Simultaneous internal fixation and latissimus dorsi pedicle flap coverage: A reliable regimen for open fractures with accompanying sizable soft tissue loss of the upper extremities

BACKGROUND

The optimal treatment protocol for open fractures with accompanying sizable soft tissue defect of the upper extremities has not been specifically delineated. The authors described the concurrent use of internal fixation and latissimus dorsi (LD) pedicle flap coverage in managing such complex fractures.

METHODS

Twenty patients with open fractures accompanied by large soft tissue defect of the upper extremities (8 clavicle fractures and 12 humeral fractures) were treated by fix & LD pedicle flap. The dimension of the defect, time to fix & flap, post-operative complications, time to union and clinical measurements were recorded.

RESULTS

The mean size of the defect was 132.45 cm2 (range 6-12 x 2-20 cm2). The average time to fix & flap was 9.9 days (range 7-14). Fractures union was achieved in all patients with an average duration of 18.5 weeks (range 14-28). Regarding post-operative complications, distal flap necrosis occurred in 3 patients, retained seroma in 3 and heterotopic ossification in 1. By the Mayo Elbow Performance (MEP) score, 3 cases were considered to be excellent, 6 were good, 7 were fair and 4 were poor. By the University of California-Los Angeles (UCLA) shoulder score, 2 cases were considered to be excellent, 7 were good, 7 were fair and 4 were poor. The average Disabilities of Arm, Shoulder and Hand (DASH) score was 31.29 (range 12.5-58.3).

CONCLUSION

Fix & LD pedicle flap is a reliable regimen for open fractures with sizable soft tissue defect of the clavicle and humerus.

Dual plating for fixation failure of the distal femur: Finite element analysis and a clinical series

BACKGROUND

The optimal technique for managing distal femur fixation failure remains inconclusive. The author studied the efficacy of a combined proximal humerus locking compression plate (LCP-PH) and 3.5 mm reconstruction plate (LCP-RP) by finite element (FE) analysis and retrospectively described the clinical outcomes of the present technique in such difficult circumstances.

METHODS

Biomechanical study setting included FE models of the distal femur with remaining holes from previous distal femur LCP (LCP-DF) fixation stabilized with three different constructs i.e., LCP-DF alone, LCP-DF-and-LCP-RP, as well as LCP-PH-and-LCP-RP. All settings were analyzed by using FE under physiological loads. Regarding the clinical series, the outcomes of 8 LCP-DF fixation failures operated on by the present technique were retrospectively reviewed.

RESULTS

High Implant stress of 911.2 MPa and elastic strain at fracture site of 200.8 µɛ were found when stabilized with LCP-DF. The constructs of LCP-DF-and-LCP-RP, and LCP-PH-and-LCP-RP presented lower implant stress compared to LCP-DF, 511.5, and 617.5 MPa, respectively. The elastic strain of both dual plating constructs was also 4-5 times lower than LCP-DF and differed from each other by approximately 10 µɛ. Regarding the clinical series, bony consolidation was achieved in all cases with a mean duration of 28.5 weeks (range 24-36). An average ROM of the affected knee was 115° (range 105-140). Regarding the KSS, 1 was determined to be excellent and 7 to be good.

CONCLUSION

By the biomechanical analysis and the clinical results, the construct of LCP-PH-and-LCP-RP could be an effective technique for revision surgery of LCP-DF fixation failure.

Modified pin and plate fixation for low intercondylar fractures of the humerus: biomechanical study corroborated with a case series

BACKGROUND

Establishing fracture union of low and comminuted intercondylar fractures of the humerus is inherently challenging. The purposes of the present study were to investigate the biomechanical effectiveness of pin & plate (PP) fixation compared to other dual-plating techniques by finite element analysis, and to present a technical description as well as retrospectively review the outcomes of PP fixation in such difficult fractures.

METHODS

Low-level intercondylar fracture 3D models of the humerus were virtually stabilized with three fixations on lateral side including PP, lateral pre-contoured locking compression plate (L-LCP), and variable angle lateral pre-contoured locking plate (VA-L-LCP) whereas medial pre-contoured locking compression plate (M-LCP) on medial side. Loading conditions under consideration were axial compression, internal rotation, posterior bending, and valgus rotation. Regarding the clinical series, eight patients with intra-articular and comminuted fractures of the distal humerus (6 intercondylar fractures, 1 fracture-subluxation, and 1 isolated lateral condylar fracture) were operated by isolated PP fixation or combinations of PP and the other standard implants. Data were collected on fracture union, perioperative complications, and objective clinical outcomes.

RESULTS

Biomechanical results revealed the most instability of the fracture occurring under posterior bending. PP fixation presented comparable fracture stability and fragment displacement compared to other dual-plating fixations, except stress on the Kirschner wire under internal rotation which was higher than other fixations. Regarding the clinical series, fracture union was achieved in all cases with an average union time of 17 weeks (range 12-20). All except one patient had good-to-excellent MEPS results with an average Disabilities of the Arm, Shoulder, and Hand (DASH) score of 14.6 (range 0-45) and an average arc of elbow motion of 107.5 degrees (range 60-140).

CONCLUSION

By the biomechanical performance, PP fixation is a reliable technique for fixation of low intercondylar fractures of the humerus. Supported by the clinical outcomes, the present technique could be an alternative for this particular fracture especially when severe comminution prevents the use of the standard dual plating technique.

Minimally invasive plate osteosynthesis via posterior approach for type B and C fractures of distal humeral shaft: surgical tactics and a clinical series

The optimal technique and implant for fixation of multifragmentary fractures of the distal humeral shaft remain inconclusive. We describe the use of minimally invasive plate osteosynthesis (MIPO) via posterior approach and extra-articular distal humerus locking compression plate (LCP-EADH) fixation for 18 such fractures. All fractures were united with a mean union time of 17.6 weeks (range 12-20). Transient radial nerve palsy was demonstrated in 2 patients. Six patients had 5° varus angulation and 1 had 5° valgus angulation. Triceps power was Grade 5 in all patients. The mean arc of elbow motion was 127.5 degrees (range 115-140). Six patients had an excellent MEP score and 12 had a good MEP score. As the results, posterior MIPO and LCP-EADH fixation could be an alternative for multifragmentary fractures of the distal humeral shaft, particularly for fractures with a very short distal fragment.

Minimally invasive plate osteosynthesis without floating segment fixation for segmental fracture of femur

Segmental fractures of the femur are technically difficult to manage by intramedullary nailing, the gold standard treatment. We specifically describe minimally invasive plate osteosynthesis (MIPO) without floating segment fixation for this particular fracture pattern. Twenty patients with segmental fractures of the femur were operated on by the MIPO technique. Data were collected on operative time, postoperative complications, union times, and clinical outcomes. The mean operative time was 63.5 minutes (range 50-90). There were no peri-operative complications. All fractures were united with a mean union time of 16.1 weeks (range 12-20). Regarding postoperative malalignment, limb shortening was demonstrated in 4 patients, valgus angulation in 2 and varus angulation in 3. One patient had a bent plate with 7°varus angulation. According to the Thoresen score, 13 were determined to be excellent values, 6 to be good and 1 to be fair. MIPO without floating segment fixation is a safe and effective alternative for segmental fractures of the femur especially in circumstances that are unsuitable or unfeasible for intramedullary nailing.

The utility of reverse distal femur locking compression plate in minimally invasive osteosynthesis for type C subtrochanteric fractures of the femur: technical description and a clinical series of 50 cases

BACKGROUND

Establishing fracture consolidation and avoiding postoperative complications of comminuted subtrochanteric fractures of the femur are technically challenging. The authors delineated a technical description of minimally invasive plate osteosynthesis (MIPO) by using a reverse distal femur locking compression plate (LCP-DF) and retrospectively reviewed the outcomes of these particular fractures.

METHODS

Fifty patients with 51 type C subtrochanteric fractures of the femur were operated on by MIPO and reverse LCP-DF fixation. The collected data included postoperative complications, union times, and clinical outcomes.

RESULTS

All fractures were united with a mean union time of 19.4 weeks (range 16-22). Regarding postoperative complications, asymptomatic valgus angulation occurred in five patients and trochanteric pain in six. According to Harris hip score, nine patients were determined to be excellent, 36 to be good and five to be fair.

CONCLUSION

MIPO by reverse LCP-DF is reliable and effective for type C subtrochanteric fractures of the femur particularly in situations where intramedullary nailing is not feasible.

Utilizing the various forms of the gastrocnemius muscle in fix & flap protocol: a reliable remedy for open proximal tibial fractures with accompanying soft tissue defect

BACKGROUND

Open proximal tibial fractures accompanied by soft tissue loss are substantially challenging to accomplish both bony consolidation and wound healing. The authors retrospectively delineated the utility of the various forms of the gastrocnemius muscle in fix & flap regimen for management of such complicated injuries.

METHODS

Thirty-one patients with open fracture accompanied by soft tissue loss of proximal tibia were managed by the protocol of fix & gastrocnemius flap. The collected data included implant for fixation, form of the gastrocnemius flap, postoperative complications, union time, and clinical assessment.

RESULTS

According to fixation devices, lateral anatomical locking compression plates were selected in 28 cases, dual plates in 1, and interlocking nails in 2. According to the forms of the gastrocnemius flap, medial gastrocnemius flap was utilized in 22 cases, medial hemigastrocnemius flap in 2, medial myocutaneous gastrocnemius flap in 2, lateral gastrocnemius flap in 3, and combined medial and lateral gastrocnemius flaps in 2. All flaps completely survived without any flap-related complications. Fracture consolidation was established in all patients with an average period of 19.9 weeks (range 16-26). Surgical site infection occurred in 3 cases, and delayed union in 1. By functional score of Puno, 3 cases were determined to be excellent, 27 to be good, and 1 to be fair.

CONCLUSION

Concurrent use of internal fixation and gastrocnemius flap reconstruction is a reliable and efficient protocol in managing open fractures with accompanying soft tissue defect of proximal tibia.

Danger zone for screw placement in minimally invasive plate osteosynthesis (MIPO) of diaphyseal fractures of forearm: a cadaveric study

PURPOSES

To identify the anatomical relationship between neurovascular structures and screws and to evaluate the danger zone of screw placement during minimally invasive plate osteosynthesis (MIPO) technique following the volar approach for the radius and the subcutaneous approach for the ulna in diaphyseal forearm fractures.

METHODS

Sixteen cadaveric forearms were fixed with a 3.5-mm, 14-hole, locking compression plate (LCP) using the MIPO technique with a volar approach of the radius. Two locking screws were fixed at each end via two separated incisions, and the remaining ten  screws were inserted percutaneously. The same MIPO technique was performed at the ulna with the subcutaneous approach. The forearms were then dissected to identify any damage to or direct contact between the screws and the radial artery (RA), the superficial branch of the radial nerve (SBRN), the posterior interosseous nerve (PIN), and the dorsal cutaneous branch of the ulnar nerve (DCBUN). The distances from the screws to the structures at risk, as well as the radial and ulnar length, were measured.

RESULTS

The average lengths of the radius and ulna were 24.74 cm and 25.93 cm, respectively. On the volar aspect of the radius, the danger zones of RA and SRN were between 15.26 and 81.24% of the length of the radius from the radial styloid. The zone of PIN injury at the posterior aspect of the radius was between 41.45 and 81.24% of the length of the radius from the radial styloid. Meanwhile, the danger zone of DCBUN was between 12.21 and 27.23% of the ulnar length from the ulnar styloid.

CONCLUSION

Based on our study, the percutaneous screw fixation in MIPO for the treatment of diaphyseal fractures of the forearm is a dangerous procedure, especially for the volar approach of the entire radius and the subcutaneous approach of the distal ulna.

Single lag screw and reverse distal femur locking compression plate for concurrent cervicotrochanteric and shaft fractures of the femur: biomechanical study validated with a clinical series

BACKGROUND

The optimal surgical management of concurrent cervicotrochanteric and shaft fractures of the femur has not been consensual. The authors investigated the reliability of combined single lag screw and reverse distal femur locking compression plate (LCP-DF) by finite element (FE) study and retrospectively described the present technique for these dual fractures.

METHOD

Intact femurs were derived from CT data, and the implant models were created by using CAD software. The fractured femur and implant models were virtually aligned based on the surgical techniques before converting to the FE model. In the FE model, applied boundary conditions included body weight, muscle forces, and constraint of the joints. Regarding clinical series, three patients with these dual fractures of the femur and 2 with cervicotrochanteric fractures with subtrochanteric extension were operated on by the proposed technique. The collected data include operative time, postoperative complications, union times, and clinical outcomes.

RESULTS

Equivalent von Mises stress exhibited on dynamic hip screws with an anti-rotational screw was higher than the other techniques, close to the yield stress of the material. Multiple screw fixation produced better stability for transcervical fractures whereas the proposed technique of combined single lag screw and reverse LCP-DF provided better stability for intertrochanteric fractures. No significant difference in cortical bone stress was found between multiple screw construct and the proposed technique. The proposed technique presented a lower risk of secondary fractures, as the strain energy density (SED) in cancellous bone was lower than multiple screw construct. Regarding clinical series, all fractures were united with a mean union time of-16.1 weeks (range 12-20). There were no any postoperative complications. Regarding the Harris score, 1 was determined to be excellent value, and 4 to be good.

CONCLUSION

By the FE results, a combination of a single lag screw and reverse LCP-DF is an effective technique for fixation of cervicotrochanteric fractures. Empowered by the clinical results, this proposed technique could be an alternative for concurrent cervicotrochanteric and shaft fractures of the femur especially when either single-system or dual-system devices seem not to be suitable.

Concurrent internal fixation and soft tissue reconstruction by distally based sural flap: a practicable scheme for complex distal tibial fractures

BACKGROUND

It is difficult to establish both fracture union and wound healing of open fractures complicated with soft tissue defects of the distal tibia. We describe the simultaneous use of internal fixation and soft tissue coverage by a distally based sural flap (DBSF) for these complex injuries.

METHODS

Seventeen patients with Gustilo IIIB open fractures of the distal tibia were operated on by internal fixation and DBSF coverage. Data were collected on the size of the defect, time to fixation and soft tissue coverage or 'fix & flap', types of implant, time to union, postoperative complications and objective clinical measurement.

RESULTS

The average size of the soft tissue defect after debridement was 6.4 × 8.4 cm² (range 4.0-9.0 × 6.0-12.0). The mean time to fix & flap was 8.1 days (range 7-10). A medial precontoured plate was used in 8 patients and an anterolateral precontoured plate in 9. All fractures were united in a mean duration of 22.6 weeks (range 20-28). One patient had partial flap necrosis. Using the Puno functional score, 2 patients had excellent functional outcomes and 15 patients had good functional outcomes.

CONCLUSION

Concurrent Internal fixation and soft tissue reconstruction by DBSF is effective and reproducible for Gustilo type III open fractures of the distal tibia even in cases of more than 50 cm² soft tissue defects.

Outcomes Following Temporary Kapandji Pinning Technique and Distal Radial LCP Fixation for Intra-Articular Fractures of the Displaced Distal Radius

In partially or completely displaced intra-articular fracture of the distal radius , achieving satisfactory reduction and maintenance of good reduction before applying the plate may be difficult. Especially to accomplish the anatomic volar tilt remains a problem. Typically, the Kapandji technique has been described to reduce and stabilize a large displaced and extra-articular fracture of the distal radius. We present the results of a prospective series using the temporary Kapandji technique for K-wire intrafocal fixation followed by rigid fixation with distal radial locking compression plate. The mean follow-up period totaled 12 months. A total of 57 patients were evaluated by radiographic and clinical review. The modified Mayo wrist score was used for postoperative patient evaluation. The clinical results on follow-up were good to excellent. Minimal joint stiffness and functional outcomes of the wrist and elbow were satisfactory. Statically significant differences were found between the preoperative and postoperative radiologic parameters. No skin infection due to K-wire insertion was noted, and the fracture healed completely in every case. This paper reports the results of 57 cases of intra-articular fractures of the distal radius treated by Kapandji wires as a reduction tool and definitive fixation by the application of a locked volar plate. It could be performed easily and reliably. K-wires were used to temporarily maintain reduction throughout the rigid fixation without further displacement in the follow-up clinic. The results proved appropriate, and the technique has merit, as it obviates the need for dorsal exposure in most cases.

Closed flexor pulley rupture of the thumb: case report and review of literature

Closed flexor pulley rupture of the thumb is extremely rare. We report a case with this condition. The anatomic and biomechanical studies, clinical and operative finding as well as the management of the closed flexor pulley rupture of the thumb are discussed.

Recovery of brachial plexus injury after shoulder dislocation

Brachial plexus injury is an underestimated complication from anterior dislocation of the shoulder. To our knowledge, there is limited information available about the factors that influence neurological recovery of this injury. We reviewed 15 upper extremities in 14 patients with brachial plexus injuries caused by anterior shoulder dislocation. Two-thirds of the cases had total brachial plexus palsy. With the conservative treatment, the motor recoveries of all cases are full or nearly full within 20 months except intrinsic muscle of the hand. Intrinsic muscle recovery may be better in a younger age group (less than 50 years). Nerve exploration is usually unnecessary. However, reconstructive surgery for the residual neurological deficit can provide improvement of hand function.

Nerve transfer to deltoid muscle using the intercostal nerves through the posterior approach: an anatomic study and two case reports

PURPOSE

To evaluate the feasibility of restoring the deltoid function in patients with C5 through C7 root avulsion injuries by transferring 2 intercostal nerves to the anterior branch of the axillary nerve through a posterior approach. The preliminary results of the clinical application of this procedure also are reported.

METHODS

The study was performed on 10 fresh cadavers. The lengths of the third, fourth, and fifth intercostal nerves from the costochondral junction to the midaxillary line were recorded. The distance from the pivot point at the midaxillary line to the anterior branch of the axillary nerve was recorded as the tunnel length. All histomorphometric measurements of the axon number were recorded. Based on the anatomic study, the fourth and fifth intercostal nerves were transferred directly to the anterior branch of the axillary nerve in 2 patients.

RESULTS

The average distances from the costochondral junction of the third, fourth, and fifth intercostal nerves to the pivot points were 12, 15, and 16 cm, respectively. The average tunnel distances of the third, fourth, and fifth intercostal nerves were 11, 13, and 15 cm, respectively. The average numbers of myelinated nerve fibers of the third, fourth, and fifth intercostal nerves were 742, 830, and 1,353, respectively. At the 2-year follow-up evaluation the preliminary clinical results showed that the deltoid recovered against resistance (M4). The range of motion for shoulder abduction and external rotation were both 95 degrees in the first case and 105 degrees and 95 degrees , respectively, in the second case. Useful functional recovery was achieved and classified as a good result in both patients.

CONCLUSIONS

This anatomic study with 2 case reports supports the idea that transfer of 2 intercostal nerves to the anterior branch of the axillary nerve through the posterior approach could be an alternative method for reconstruction of the deltoid muscle in C5 through C7 root avulsion injuries.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.