Risk of axillary nerve injury during percutaneous proximal humerus locking plate insertion using an external aiming guide

Objectives

The purpose of this study was to determine which screws could be safely inserted percutaneously into a proximal humerus locking plate using a new external aiming guide without injuring the axillary nerve. We also sought to evaluate that all the screws could be accurately inserted in a locked position with the external guide.

Methods

Eight cadaveric specimens were implanted with a proximal humerus locking plate using a minimally invasive direct-lateral deltoid splitting approach using an attached external aiming guide for screw insertion. The anatomic proximity of the axillary nerve to the guidewires and screws was measured following soft tissue dissection and inspection of the nerve.

Results

The two superior holes (C1 and C2) were proximal to the axillary nerve with an average distance of 15.1 mm. Screw F was on average 6.6 mm distal to the axillary nerve but within 2 mm of the nerve in two specimens. In all specimens, the locking screws were appropriately seated in a locked position using the external aiming guide.

Conclusions

This study suggests that percutaneous fixation of a proximal humerus locking plate with an external aiming guide can be safely used for proximal humerus fractures. The limited number of screws that can be inserted into the proximal fragment using the current external guide arm may compromise fixation of more unstable fractures. Therefore, the indications for percutaneous locking plate fixation of the proximal humerus using an external aiming guide should be limited to stable fracture patterns that can be anatomically reduced.     

Screw fixation of radial head fractures: Compression screw versus lag screw—A biomechanical comparison

Introduction

Secondary loss of reduction and pseudarthrosis due to unstable fixation methods remain challenging problems of surgical stabilisation of radial head fractures. The purpose of our study was to determine whether the 3.0 mm Headless Compression Screw (HCS) provides superior stability to the standard 2.0 mm cortical screw (COS).

Materials and methods

Eight pairs of fresh frozen human cadaveric proximal radii were used for this paired comparison. A standardised Mason II-Fracture was created with a fragment size of 1/3 of the radial head's articular surface that was then stabilised either with two 3.0 mm HCS (Synthes) or two 2.0 mm COS (Synthes) according to a randomisation protocol. The specimens were then loaded axially and transversely with 100 N each for 4 cycles. Cyclic loading with 1000 cycles as well as failure load tests were performed. The Wilcoxon test was used to assess statistically significant differences between the two groups.

Results

No statistical differences could be detected between the two fixation methods. Under axial loads the COS showed a displacement of 0.32 mm vs. 0.49 mm for the HCS. Under transverse loads the displacement was 0.25 mm for the COS vs. 0.58 mm for the HCS group. After 1000 cycles of axial loading there were still no significant differences. The failure load for the COS group was 291 N and 282 N for the HCS group.

Conclusion

No significant differences concerning the stability achieved by 3.0 mm HCS and the 2.0 mm COS could be detected in the experimental setup presented.     

Routine use of locking shaft screws is not necessary in volar plate fixation of distal radius fractures

Hypothesis

Volar locking plate fixation is a common treatment method for distal radius fractures. Recently, implants have been designed with an option to use locking screws in the shaft portion of the plate. While there is a high incidence of low bone mineral density in patients who sustain fragility fractures of the distal radius, the need for locking shaft screws is not well defined. Our hypothesis is that the routine use of locking screws in the shaft portion of volar plates is not required to maintain reduction or to prevent hardware failure.

Methods

A retrospective review was performed in all patients over age 50 years who underwent volar plate fixation using an implant with non-locking shaft screws for a distal radius fracture during a 2-year period. Patients were permitted to perform early range of motion exercises. Radiographs were examined and measurements were obtained to assess maintenance of reduction and incidence of hardware failure. Patients were followed at least until fracture healing. Patients were excluded from analysis if locking shaft screws were utilized or if follow-up was inadequate.

Results

Forty-one patients met the inclusion criteria. The average age was 62 years (range 50–79). There were 12 men and 29 women. The implant used incorporated 3.5-mm shaft screws in 26 patients and 2.4-mm shaft screws in 15 patients. All patients healed within acceptable radiographic parameters (mean volar tilt = 4.9°, mean radial inclination = 21.7°, mean radial height = 11.6 mm). There were not any instances of hardware failure.

Discussion

Distal radius fractures frequently occur in patients with low bone mineral density. Non-locking, bicortically placed shaft screws provide adequate stability to allow for early range of motion without loss of reduction or hardware failure. The routine use of locking screws in the shaft portion of volar plates does not appear justified.     

Correcting rotational deformity following femoral nailing

Introduction

The incidence of rotational malalignment after femoral nailing has been reported to be at least 20%. If the deformity is recognised early, it can be corrected by changing the distal locking screw and rotating the bone prior to fracture union. It is common practice to use the same distal locking screw of the nail if this surgery is performed, however, there is a risk of the new drill hole “cutting out” into the old screw hole. The degree of rotational deformity that needs to be corrected to use the same distal locking hole without cut out of the screw has not been defined.

Method

Ten femora, five from cadavera and five synthetic (“Synbone”), were stabilised in a vice and then fitted with one distal transverse screw. The screw was then removed and a second distal transverse screw was inserted at the same level after variable amounts of rotation. The bone bridge between the drill holes was then measured and any cut out was noted.

Results

Both of the femora cut out when rotated 10°, and one when rotated 15°. The size of the bone bridge between drill holes in femora rotated by 20° was 3 mm. This bone bridge was increased to 4 mm when the femora were rotated by 25°, and 8 and 9 mm when rotated by 30°.

Conclusion

The amount of rotational deformity that needs to be corrected in order to use the same distal locking hole in a femoral nail is significant. In our study, this equates to a correction of at least 25°, but this is not a definitive value in practice. Particular attention must be paid to the location and size of the distal locking screw when correcting malrotation after femoral nailing, to ensure an adequate bone bridge between the two holes.     

Influence of plate–bone contact on cyclically loaded conically coupled locking plate failure

Introduction

The maintenance of friction between locking plates and bone is not essential, so that they can be applied with a gap between the plate and underlying bone. We hypothesised that the presence of a gap under a locking plate with a conical coupling mechanism would reduce fixation stability or allow uncoupling of the locking screws from the plate.

Materials and methods

Locking plates with two conically coupled locking screws were applied to 6 pairs of adult canine femora. One of each pair had plate to bone contact and the contralateral construct had a 2 mm plate to bone gap. Constructs were cyclically loaded in cantilever bending with 10 percent incremental increases every 1000 cycles at 2 Hz, starting at 250 N. The constructs were fatigued to failure. To evaluate fatigue life of the conical coupling, testing was repeated with aluminium tubing replacing the bone, to eliminate screw–bone cutout failure.

Results

The mean sustained loads and cycles to failure in the contact group (420.80, standard error [SE] 14.97 N; 7612.00, SE 574.70 cycles) were significantly greater than in the gap group (337.50, SE 14.97 N; 4252.00, SE 574.70 cycles), (p < 0.001). Failure mode of all bone constructs was via screw cutout from the bone. Aluminium tubing constructs failed via screw or plate fatigue and breaking, with one construct having elevation of the plate over the screw head.

Discussion and conclusions

Elevation of locking plates with a conical coupling system by 2 mm from the bone reduced construct fatigue life but did not result in screw head uncoupling from the plate.     

Clinical and radiologic outcomes associated with the use of dynamic locking screws (DLS) in distal tibia fractures

Background

The locked screw plate construct is often cited as being too rigid and prolonging healing in patients with metaphyseal fractures. The newly introduced dynamic locking screws (DLS) allow 0.2 mm of axial motion, which should optimize healing near the near cortex. The purpose of this study was to analyze the clinical results of dynamic locking screws in distal tibia fractures.

Methods

Data were acquired retrospectively. Only distal meta-diaphyseal tibia fractures treated with minimally invasive plate osteosynthesis and DLS were evaluated. Cortical and locking head screws were used for distal plate fixation to minimize soft tissue irritation over the medial malleolus, and DLS were used in the proximal plate fixation. Clinical and radiographic data were evaluated after 6 weeks, 3 months, 6 months and 1 year until fracture union.

Results

Twenty-two patients were treated with minimally invasive plate osteosynthesis and DLS. Six patients could not be evaluated because they returned to a foreign residence after the procedure. Fourteen fractures healed after a mean of 3.1 months. Two fractures with insufficient reduction showed delayed union and healed after 9 and 9.5 months, respectively. The callus index peaked at 6 months.

Conclusions

Dynamic fracture fixation might be a promising concept to reduce the frequency of metaphyseal non-unions in distal tibia fractures. But nevertheless, the dynamic construct cannot compensate for insufficient reduction.

     

Case Report: A Technique to Remove a Jammed Locking Screw from a Locking Plate

Background  

Locking titanium plates revolutionized the treatment of osteoporotic and metaphyseal fractures of long bones. However as with any innovation, with time new complications are identified. One of the problems with titanium locking plates is removal of screws, often attributable to cold welding of screw heads into the locking screw holes. Several techniques have been described to overcome this problem. We describe a new easy technique to remove a jammed locking screw in a locking plate that is easily reproducible and suggest an algorithm to determine the method to remove screws from locking plates.     

Surgery improves quality of life in patients with “mild” hyperparathyroidism

Background

Surgical treatment of patients with “classic” hyperparathyroidism improves quality of life, but these benefits to patients with “mild” disease remain unclear.

Methods

The SF-36 Health Survey was administered to 174 patients 1 week before, 1 week after, and 1 year after undergoing parathyroidectomy.

Results

One hundred fifty-one patients completed at least 2 surveys. There were 18 and 133 cases of “mild” and “classic” hyperparathyroidism, respectively. Preoperatively, the groups did not differ significantly in the 10 scales. One year after surgery, patients with “classic” and “mild” disease improved significantly in 9/10 and 10/10 scales, respectively (P < 0.05). Those with “mild” disease had a statistically larger improvement than those with “classic” disease in 4 scales.

Conclusions

Quality of life significantly improved in surgically treated patients with both “mild” and “classic” hyperparathyroidism, supporting surgical treatment of “mild” hyperparathyroidism. Moreover, quality of life may improve more in patients with “mild” rather than “classic” disease.     

The significance of contrast blush on computed tomography in children with splenic injuries

Purpose

Most children and adults with blunt splenic injuries are treated nonoperatively by well-established management protocols. The “blush sign” is an active pooling of contrast material within or around the spleen seen during intravenous enhanced computed tomography (CT) scan. Adult treatment algorithms often include the “blush sign” as an indication for embolization or surgical intervention. This study was designed to evaluate the implications of the “blush sign” in children with blunt splenic injuries.

Methods

A review was performed of all children with blunt splenic injuries treated between January 1996 and December 2001 at a level I pediatric trauma center using an established solid organ injury protocol. The demographic, CT imaging, and outcome data were recorded. Treatment was categorized as operative or nonoperative. A single pediatric radiologist retrospectively reviewed all available CT scans to confirm injury grade and the presence or absence of a “blush sign.”

Results

There were 133 eligible children admitted with blunt splenic trauma, with a mean age of 9.1 years (range, 1 to 15), including 86 children with an abdominal CT available for review. A “blush sign” on initial CT scan was noted in 6 children, all with grade 3 or above splenic injuries, 5 of who were treated nonoperatively. In this series, the single child with a “blush sign” who did not respond to nonoperative treatment had a severe polytrauma requiring urgent splenectomy and left nephrectomy. None of the children died of their splenic injury.

Conclusions

Although associated with higher grades of injury, the blush sign did not mandate embolization or surgical intervention in children with blunt splenic trauma in this series. Severe splenic injuries with a blush sign on the initial CT scan may be successfully treated nonoperatively when using an established treatment protocol. Management should be based primarily on physiological response to injury rather than the radiologic features of the injury.     

Different stabilisation techniques for typical acetabular fractures in the elderly—A biomechanical assessment

Objectives

The tremendous increase of acetabular fractures in the elderly provides new challenges for their surgical treatment. The aim of this study was to evaluate the biomechanical properties of conventional and newly developed implants for the stabilisation of an anterior column combined with posterior hemitransverse fracture (ACPHTF), which represents the typical acetabular fracture in the elderly.

Methods

Using a single-leg stance model we analysed four different implant systems for the stabilisation of ACPHTFs in synthetic and cadaveric pelvises. Applying an increasing axial load, fracture dislocation was analysed with a new multidirectional ultrasonic measuring system. Results of the different implant systems were compared by Scheffé post hoc test and one-way ANOVA.

Results

In synthetic pelvises, the standard reconstruction plate fixed by 3 periarticular long screws and a new titanium fixator with multidirectional interlocking screws were associated with significantly less dislocation of the fractured quadrilateral plate of the acetabulum when compared to a standard reconstruction plate fixed by only one periarticular long screw and a locking reconstruction plate. No significant differences between the different osteosynthesis techniques could be observed in cadaver pelvises, probably due to a heterogeneous bone quality.

Conclusions

We conclude that the plate fixation by positioning of periarticular long screws as well as the multidirectional positioning of interlocking screws account for the most sufficient fracture stabilisation of ACPHTFs under experimental conditions.     

Carotid endarterectomy in high-risk patients: a challenge for endovascular procedure protocols

Background

Many studies have sought to identify certain patient population subsets that may be more appropriate for carotid angioplasty and stenting (CAS). Current CAS protocols include “high-risk” patients. The goal of this study was to compare the perioperative outcome of carotid endarterectomy (CEA) between high-risk and non-high-risk patients.

Methods

During a 54-month period, 392 consecutive CEAs were performed in 363 patients (29 bilateral) by a single surgeon and entered prospectively into a registry. A high-risk patient subset (126, 35%) was defined by the presence of a severe medical comorbidity (ie, cardiac dysfunction, pulmonary dysfunction, renal insufficiency) or particular anatomic features (ie, contralateral carotid occlusion, ipsilateral carotid restenosis after CEA, and “high” carotid bifurcation). Of the 126 CEAs, 96 (76%) were performed for symptomatic lesions. Endpoints of the study were perioperative stroke, cardiac complication, or death.

Results

Overall, there were three ischemic strokes (1%) and four cardiac complications (1%). None of the patients died. The stroke and cardiac complication rates for the high-risk and non-high-risk groups were similar (1/126, 1% versus 2/237, 1% and 3/126, 2% versus 1/237, 1%, respectively), but the cardiac morbidity rate was statistically higher in patients with severe medical comorbidity (P = .03), especially in the subset with cardiac dysfunction (P = .005).

Conclusions

CEA can be performed in high-risk patients with perioperative neurologic and cardiac complication rates comparable with those recorded in other patients. The definition of a “high-risk” patient should not be considered per se a reason to abandon CEA in favor of CAS.     

Upper cervical spine injuries: indications and limits of the conservative management in Halo vest. A systematic review of efficacy and safety

Introduction

The integrity of the upper cervical spine is essential for survival and function, because of the neurovascular structures contained within its bony elements. Fractures of the upper cervical spine (C1-C2) are frequent. This systematic review assesses the efficacy and safety of the conservative management in Halo vest for patients with upper cervical spine fractures.

Materials and methods

Two reviewers independently identified studies in English, by a systematic search of CINAHL, Embase, Medline, HealthSTAR, and the Cochrane Central Registry of Controlled Trials, from inception of each database to 28 January 2010, using various combinations of the keywords terms “odontoid fractures”, hangman's fractures”, “axis fractures”, “axis”, “atlas”, “Jefferson fractures”, “C1 arch fractures”, “C1 fractures”, “C2 fractures”, “cervical spine”, “injuries”, “fracture”, “trauma”, “neck injury”, “surgery”.

Results

A total of 43 citations were obtained. An additional 4 papers were obtained from the reference list of the studies included. The 47 studies that were included described a total of 1078 patients with C1-C2 fractures managed by halo fixator.

Conclusions

The halo fixator has a well defined place in the management of fractures of the cervical spine. Clearly, studies of higher level of evidence, for instance large randomised trials, should be conducted, even though the available evidences suggest that management of upper cervical spine facture with halo fixator is safe and effective.     

Can we safely place the distal volar locking plate screws into the subchondral zone of a distal radius fracture using a 45° supination oblique view under fluoroscopic guidance?

IntroductionCareful distal locking screw insertion into the subchondral zone is necessary to obtain proper mechanical strength of unstable distal radius fractures using volar locking plating. However, subchondral zone screw insertion increases the risk of intra-articular screw penetration, which may remain unrecognized during surgery due to complex distal radial anatomy. The purpose of this study was to evaluate the role of fluoroscopic guidance with a 45° supination oblique view technique for placing distal screws into the subchondral zone during volar locking plating for unstable distal radius fractures and to explore the factors associated with poor screw placement.MethodsWe retrospectively analyzed 171 wrists of 169 patients treated with variable-angle volar locking plates for unstable radius fractures. The subchondral zone was defined as the metaphyseal area within 4 mm of the articular margin of the distal radius. The location of the distal locking screws and radiographic parameters, including the teardrop angle, were measured using computed tomography scans and X-rays. Clinical and radiographic factors were examined to determine their possible associations with screw placement failure.ResultsOf 581 distal screws inserted, 559 screws (96.2%) were inserted into the subchondral zone and 17 screws into the metaphyseal zone (2.9%). Five screws (0.7%) in three wrists showed intra-articular placement: four screws were placed into the lunate fossa and one into the scaphoid fossa. These three wrists also exhibited significantly reduced teardrop angles. The distal screws were significantly closer to the joint line in the lunate fossa than the scaphoid fossa (1.9 ± 0.9 mm vs. 2.8 ± 1 mm, P < 0.000).ConclusionThe 45° supination oblique view technique is a useful fluoroscopic guiding technique for accurate and safe distal screw placement in the subchondral zone in volar locking plate fixation for distal radial fractures. However, a decreased teardrop angle or extended lunate fossa should be corrected before distal screw insertion to avoid intra-articular screw placement.     

Delayed bone healing following high tibial osteotomy related to increased implant stiffness in locked plating

Introduction

Asymmetrical callus formation and incomplete bone formation underneath stiff locking plates have been reported recently in clinical and experimental fracture healing studies. After similar effects were observed in the outcome of high tibial osteotomy (HTO) patients, a retrospective study was performed to quantify the frequency and level of such incomplete healing cases.

Material and methods

Twenty-three patients treated with medial open wedge HTO and locking plate (Tomofix™) for posttraumatic or congenital genu varum were investigated. No bone grafts were applied to fill the osteotomy gap. The median correction angle was 8° (5–18°). Elective hardware removal was performed after a median of 19.5 months (12–58 months) following an uneventful clinical course. The most recent postoperative X-ray available (median 21 months; 13–56 months) was evaluated for consolidation of the osteotomy. We performed an in vitro biomechanical experiment using the same HTO on a loaded cadaver knee joint to compare interfragmentary movements (IFMs) when using regular locking screws with the Tomofix™ plate and screws that enabled dynamic stabilisation of this plate.

Results

Fifteen patients (65%) displayed incomplete consolidation of the osteotomy underneath the locking plate (10.9% of the osteotomy length) and cortical deficiency. The time to implant removal for these patients of 27 months was longer than the 21 months for the patients with a complete osteotomy gap healing. The biomechanical experiment demonstrated that very low IFMs and corresponding interfragmentary strain occur underneath the plate when using regular locking screws. Replacement with dynamic screws resulted in an increased IFM.

Discussion and conclusions

These results support the hypothesis that low bone formation underneath locking plates is induced by increased stiffness. This high stiffness situation could be altered by replacing the standard screws with dynamic screws which allow for a movement of 0.35 mm perpendicular to the screw axis. This resulted in an approximately threefold increase in the IFM and may be a potential concept to avoid incomplete bone healing under stiff plate fixations.     

Obsessive-compulsive psychological symptoms of patients on the liver transplant waiting list

Introduction

Patients on the liver transplant waiting list have increased emotional and clinical symptoms. The presence of psychopathologic symptoms associated with obsession-compulsion as a reflection of alterations due to anxiety disorders is common in these patients.

Objective

To evaluate obsessive-compulsive psychopathological symptoms in patients on the liver transplant waiting list.

Materials and methods

The study included 50 patients on the liver transplant waiting list. The instrument was the SA-45 questionnaire (Derogatis, 75), whose Spanish version was adapted by González Rivera and De las Cuevas (1988). This dimension was evaluated using five statements.

Results

Among of the patients on the liver transplant waiting list, 46% had no relevant obsessive-compulsive symptoms. Of these, 28% had no symptoms and 18% had some symptoms, but the overall evaluation in these patients was no greater than the cutoff point. The remaining 54% had relevant obsessive-compulsive clinical symptoms, most commonly (1) “Having difficulty making decisions” (P < 3.45 · 10⁻⁹); (2) “Having difficulty concentrating” (P < 1.70 · 10⁻⁸); (3) “One's mind goes blank” (P < 3.04 · 10⁻⁴); (4) “Having to repeatedly check everything being done” (P < 1.37 · 10⁻¹); and (5) “Having to do things slowly to make sure they are done properly” (P < 5.02 · 10⁻¹).

Conclusions

Many patients on the liver transplant waiting list have obsessive-compulsive psychopathologic symptoms. Their detection and application of adequate psychological treatment are important to minimize the effects of emotional changes onward from the pretransplant phase.     

Less rigid stable fracture fixation in osteoporotic bone using locked plates with near cortical slots

Introduction

Locked plating leads to improved fixation in osteoporotic bone. In addition, experimental data suggest that overall construct stiffness is increased. Ideal stiffness may be significantly less than that achieved with these locked constructs, and overly stiff constructs may lead to impaired fracture healing and stress concentration at the ends of the plate. In osteoporotic bone, this stiffness mismatch can be even more pronounced. We hypothesized that substituting slots for holes in the near cortex under a locked plate would lead to predictably lower stiffness without diminishing implant stability.

Methods

Osteoporotic bone substitute segments were used. Locking screws and plates were applied to each specimen using either standard holes or near cortical slots. The slots were designed to allow axial displacement of the screw in the near cortex only, while continuing to provide some torsional stability. Mechanical testing was performed using a progressive dynamic displacement load protocol to determine failure and stiffness. Next, cyclic axial loading was performed with a physiologic load for 10,000 cycles to determine change in stiffness with cycling. Outcomes were compared between groups using Mann-Whitney U tests.

Results

In the dynamic displacement tests, the slotted specimens reached both maximum load and failure load at a significantly greater displacement than the non-slot group (p = 0.008), indicating later failure. The magnitude of the maximum load achieved was no different between groups. In the cyclic loading tests, the axial stiffness in the slotted group was significantly lower (1199 N/mm) than the non-slotted group (3538 N/mm; p < 0.05 at all cycles). Stiffness did not change significantly in either group over the course of cycling.

Discussion

The ability to predictably adjust the axial stiffness of locked plating constructs is critical, particularly in osteoporotic bone. The use of near cortical slots decreases axial stiffness of locking plates, while maintaining fixation stability. This may allow the surgeon to more closely tailor the construct stiffness to the clinical situation to minimize stiffness mismatches and complications.     

Minimally Invasive Anterior Plate Osteosynthesis in Humeral Shaft Fractures

Abstract   Twelve patients with shaft fractures of the humerus were treated with percutaneous anterior plate osteosynthesis using a deltoid-pectoral respectively brachialis splitting approach without exposure of the radial nerve. The implants used were PHILOS plates, locking compression plates 3.5 and 4.5, and a tibial metaphyseal plate (all by Synthes). There were no intraoperative complications, no infections and no iatrogenic injuries of the radial or axillary nerve. Nine fractures healed entirely. There was one pseudarthrosis caused by a plate that was too short; another fracture probably healed but the distal screws broke; and one patient was lost to follow-up. Minimally invasive anterior plate osteosynthesis in humeral shaft fractures is an operative alternative which may be indicated not only in delayed healing or complex shaft fractures.     

Is dopexamine superior to dopamine in the treatment of multiple trauma patients—A prospective, double-blind, randomised study

Background

The goal of this prospective, randomised, double-blind clinical trial study was to assess the effects of dopexamine hydrochloride on organ failure, inflammatory mediators and splanchnic oxygenation in blunt multiple trauma patients at high risk of multiple organ dysfunction syndrome (MODS).

Methods

We performed a prospective randomised controlled trial on 30 consecutive blunt multiple trauma patients with ISS ≥ 16, age 18-60 years and initial blood pressure ≥120 mmHg initially admitted to our level I trauma centre. Patients were randomised to treatment with dopamine (n = 15) or dopexamine (n = 15) for 48 h after admission. Outcome in terms of mortality, MODS, splanchnic perfusion, complications, duration of stay was statistically analysed.

Results

Dopexamine treatment was associated with impaired organ function and an increased duration of ventilation and ICU stay compared with patients who received dopamine treatment. The acute inflammatory response was increased in the Dopexamine group while a decreased pHi and MEGX formation and increased serum lactate levels were measured.

Conclusions

The indication to use dopexamine hydrochloride appears questionable. In the absence of an antiinflammatory effect, dopexamine demonstrated a disadvantageous ICU course in regards to the organ function and the duration of treatment. In addition, a decreased pHi and MEGX formation suggested a deterioration of splanchnic oxygenation.     

Plating of metacarpal fractures with locked or nonlocked screws,a biomechanical study: how many cortices are really necessary?

Background

Dorsal plate and screw fixation is a popular choice for metacarpal stabilization. The balance between construct stability and soft tissue dissection remains a surgical dilemma. Historically, six cortices of bone fixation on either side of a fracture were deemed necessary. This study aims to elucidate whether four cortices of locked fixation on either side of the fracture is equivalent to the current gold standard of six cortices of nonlocked fixation on either side of the fracture. If so, less dissection to insert shorter plates with fewer screws could be used to stably fix these fractures.

Methods

With biomechanical testing-grade composite Sawbones, a comminuted metacarpal fracture model was used to test two fixation constructs consisting of a standard dorsal plate and either six bicortical nonlocking screws (three screws per segment) or four bicortical locking screws (two screws per segment). Thirty specimens were tested to failure in cantilever bending and torsion.

Results

There was statistical equivalence between the locking and nonlocking constructs in cantilever bending stiffness, torsional stiffness, maximum bending load, and maximum torque.

Conclusion

The tested metacarpal fracture model had equivalent biomechanical properties when fixed with a standard dorsal plate and either six bicortical nonlocking screws or four bicortical locking screws. By utilizing fewer cortices of fixation, there will be less dissection and less soft tissue stripping during fixation of metacarpal fractures. This will also be of benefit in very proximal or distal fractures as multiple cortices of fixation are often difficult to obtain during stabilization of these challenging fractures.