Acromioclavicular joint reconstruction by coracoid process transfer augmented with hook plate

Background

Various techniques have been reported for the treatment of chronic acromioclavicular (AC) joint separation. The purpose of this study was to evaluate the results of surgical construction of coracoclavicular ligament using coracoid process transfer augmented with a hook plate fixation.

Materials and methods

Twenty-one patients treated with coracoid process transfer augmented with a hook plate fixation for chronic type III and V AC injuries were retrospectively analysed in 2003–2009. The age of the patients ranged from 23 to 58 years with an average age of 41.6 years. The patients were followed up clinically and radiographically, with an average of 33.0 months. Functional status and the ability to return to work were recorded during follow-up. Constant score and visual analogue scale (VAS) for pain were measured.

Results

The mean Constant score has increased from 70.9 points preoperatively to 90.7 points at follow-up. The mean VAS score has decreased from 4.7 preoperatively to 1.2 at follow-up. The average abduction was 172°, forward flexion was 170° and external rotation was 56°. There were 10 excellent results, 10 good results and one fair result. All patients had resumed their job or returned to original sport activity at mean 3.7 months postoperatively. No reduction loss was observed after plate removal and the final follow-up.

Conclusions

Despite retrospective nature of the study, the outcomes of surgical construction with process transfer augmented with hook plate fixation are promising for chronic type III and V AC injuries.

Level of evidence

Therapeutic level IV. Retrospective case series, treatment study.     

Minimalinvasive Akromioklavikulargelenkrekonstruktion (MINAR)

Objective

Reduction and retention of an acromioclavicular (AC) joint dislocation with a button/suture augmentation cerclage (Flip tack, Karl Storz, Tuttlingen, Germany).

Indications

Dislocation of the AC joint (Rockwood III and V). Chronic instabilities in combination with autogenous replacement of the coracoclavicular ligaments. Lateral clavicular fracture with rupture of the coracoclavicular ligaments.

Contraindications

Patients in poor general condition. Local soft-tissue infection. Low-degree dislocation of AC joint (Rockwood I und II). Fracture of the clavicular shaft. Chronic instabilities without ligament replacement.

Surgical Technique

The coracoid process is exposed by a 3 cm long skin incision. A hole is drilled through the coracoid process with the help of a specific aiming device. The suture cerclage is connected to two buttons. One of the buttons is then pushed through the coracoid process. The button is flipped and the suture thereby fixed to the coracoid process. The other anchor is pulled through a hole in the clavicle and the cerclage is secured with a surgical knot after reduction of the AC joint.

Postoperative Management

Application of an abduction splint for 4 weeks (15°).

Results

23 patients with an acute luxation of the AC joint were operated with a minimally invasive coracoclavicular cerclage (five patients with Rockwood type III and 18 patients with Rockwood type V). Mean operative time was 28.6 min. Perior postoperative complications such as nerve and vascular injuries, thoracic injuries, infection, thrombosis, and embolism did not occur. The mean Constant Score was 94.1 points (73–100 points) after a mean of 23.3 months (18–28 months). In two cases, a slight loss of reposition of less than half of the clavicle width in comparison with the contralateral side was observed.     

Biomechanical Comparison of an Intramedullary and Extramedullary Free-Tissue Graft Reconstruction of the Acromioclavicular Joint Complex

Background

Several different surgical techniques have been described to address the coracoclavicular (CC) ligaments in acromioclavicular (AC) joint injuries. However, very few techniques focus on reconstructing the AC ligaments, despite its importance in providing stability. The purpose of our study was to compare the biomechanical properties of two free-tissue graft techniques that reconstruct both the AC and CC ligaments in cadaveric shoulders, one with an extramedullary AC reconstruction and the other with an intramedullary AC reconstruction. We hypothesized intramedullary AC reconstruction will provide greater anteroposterior translational stability and improved load to failure characteristics than an extramedullary technique.

Methods

Six matched cadaveric shoulders underwent translational testing at 10 N and 15 N in the anteroposterior and superoinferior directions, under AC joint compression loads of 10 N, 20 N, and 30 N. After the AC and CC ligaments were transected, one of the specimens was randomly assigned the intramedullary free-tissue graft reconstruction while its matched pair received the extramedullary graft reconstruction. Both reconstructed specimens then underwent repeat translational testing, followed by load to failure testing, via superior clavicle distraction, at a rate of 50 mm/min.

Results

Intramedullary reconstruction provided significantly greater translational stability in the anteroposterior direction than the extramedullary technique for four of six loading conditions (p < 0.05). There were no significant differences in translational stability in the superoinferior direction for any loading condition. The intramedullary reconstructed specimens demonstrated improved load to failure characteristics with the intramedullary reconstruction having a lower deformation at yield and a higher ultimate load than the extramedullary reconstruction (p < 0.05).

Conclusions

Intramedullary reconstruction of the AC joint provides greater stability in the anteroposterior direction and improved load to failure characteristics than an extramedullary technique. Reconstruction of the injured AC joint with an intramedullary free tissue graft may provide greater strength and stability than other currently used techniques, allowing patients to have improved clinical outcomes.     

Assessment of the role of fibular fixation in distal-third tibia–fibula fractures and its significance in decreasing malrotation and malalignment

Background

In the treatment of distal-third tibia/fibula fractures treated by interlocking nailing, the role of fibular fixation is not clearly defined. This study aimed to assess the benefits of fibular fixation in such fractures.

Methods

Sixty patients with fractures of the lower third of the leg were enrolled into the study and divided into two groups based on whether the fibula was fixed (group A) or not (group B). Fracture tibia was treated with interlocked intramedullary nailing and fibular fixation was done using a 3.5-mm Limited Contact Dynamic Compression Plate (LC-DCP). The two groups were compared for differences in rotation at ankle, angulation at the fracture site, time of union and complications. Clinical and functional outcomes were assessed regularly. Merchant–Dietz criteria were used to assess ankle function.

Results

The demographics of the two groups were similar. Average valgus angulation was significantly less in group A (average 5°) versus group B (average 9°). The degree of rotational malalignment at the ankle in group A was average 7° versus average 15° in group B. The outcome of two groups for clinical ankle score, time of union and complications showed no significant differences.

Conclusion

Fixation of the fibula along with interlocking nailing of the tibia decreases the malalignment of the tibia and malrotation of the ankle in distal-third fractures of the tibia and fibula as compared with only interlocking nailing.     

Arthroscopically guided navigation for repair of acromioclavicular joint dislocations: a safe technique with reduced intraoperative radiation exposure

Background

Accuracy evaluation of navigated image free placement of double cortical fixation buttons for coracoclavicular tunnel position in comparison to conventional drill guide based placement.

Methods

Twenty-six patients with acute acromioclavicular joint instability were included in this non-randomized cohort study. All patients were treated with a Double- TightRope technique. In 13 cases the conventional drill guide based placement was used (group 1). In 13 patients surgery was performed as a navigated procedure with a fluoro-free optoelectronic system (group 2). The number of coracoclavicular drillings per patient (First pass accuracy; FPA (%)) was documented, the subcoracoidal position of the fixation buttons has been evaluated and graded as “intended position achieved (IPA)” or “intended position not achieved (IPnA)”.

Results

In group 1 drilling had to be repeated in four patients (30.8 %) to achieve proper placement of the subcoracoidal fixation buttons. 100 % first pass accuracy was observed in group 2 (p?=?0.03). In group 1, the intended position of the subcoracoid buttons was not achieved (IPnA) in six patients (46.2 %). In group 2 all intended positions were achieved (p?=?0.005).

Conclusion

Arthroscopic controlled fluoro-free navigated coracoclavicular drilling for the repair of acromioclavicular joint dislocation has higher first pass accuracy in comparison to conventional drill guide based placement. Therefore the navigation enables a precise position of the drill holes, may reduce the risk of an iatrogenic coracoid fracture and migration of fixation devices.

Trial registration

Local institutional review board No. 061-14-10032014

     

Anatomie der akromiokorakoklavikulären Region

Background

The acromioclavicular (AC) joint connects the acromion with the lateral end of the clavicle and constitutes an important load-transmitting element between the upper extremity and the skeleton of the trunk.

Aim

This review discusses functional aspects that relate the AC and the coracoclavicular (CC) ligaments to AC joint instability and lateral clavicle fracture.

Results

In terms of stability the AC and CC ligaments play a pivotal role for this region. Under normal conditions the restraint system is balanced and becomes unbalanced in cases of injury such as AC joint instability or lateral clavicular fractures. Skeletal injuries frequently affect the ligaments with their usually sharp-angled insertion sites, which alters the function of the restraint system. As a consequence these injuries lead to multidirectional dislocating forces acting on the scapula in relationship to the lateral end of the clavicle. Previously, special attention was given to the vertical dislocation of the lateral clavicle, whereas less attention was paid to other factors which could lead to dislocation in other directions. Therefore, in this review emphasis is placed on the anatomical principles of multidirectional dislocation of the AC joint the fractured lateral clavicle.

Conclusion

Current clinical classification schemes fail to sufficiently include these multidirectional dislocating forces; however, they have to be considered when choosing the appropriate treatment modality. Thus, understanding the anatomical and functional context of the AC/CC region is essential for a sound management of AC joint injuries and fractures of the distal clavicle.

     

A new risk classification rule for curve progression in adolescent idiopathic scoliosis

Background context

Prognostic factors for curve progression of adolescent idiopathic scoliosis (AIS) have been reported previously. There is only one existing rule that classifies AIS patients into two groups by a curvature of 25°.

Purpose

This study aimed to develop a more refined risk classification rule for AIS.

Study design

This was a retrospective cohort study.

Patient sample

We examined 2,308 untreated AIS patients, aged 10 years and older, who had a Risser sign of 2 and lesser and a curvature less than 30° at presentation.

Outcome measures

Outcome was taken as the time to progression to 30°.

Methods

Patients' clinical parameters were analyzed by Classification and Regression Tree analysis.

Results

The new classification rule identified four risk groups of curve progression. Patients with a curvature of 26° and more and less than 18° constituted the highest and lowest risk groups, respectively. The two intermediate groups were identified by the age (11.3 years), menarcheal status, and body height (154 cm).

Conclusions

The risk classification rule only uses information at the first presentation and can aid physicians in deriving an efficient management.     

Management of acute unstable distal clavicle fracture with a modified coracoclavicular stabilization technique using a bidirectional coracoclavicular loop system

Background

Fracture of the distal clavicle is not uncommon. Despite the vast literature available for the management of this fracture, there is no consensus regarding the gold standard treatment for this fracture.

Purpose

To assess the clinical and radiographic outcomes and complications of acute unstable distal clavicle fracture when treated by a modified coracoclavicular stabilization technique using a bidirectional coracoclavicular loop system.

Methods

Thirty-nine patients (32 males, 7 females) with acute unstable distal clavicle fractures treated by modified coracoclavicular stabilization using the surgical technique of bidirectional coracoclavicular (CC) loops seated behind the coracoacromial (CA) ligament were retrospectively reviewed. Mean follow-up time was 35.7 months (range 24–47 months). The outcomes measured included union rate, union time, CC distances when compared to the patients’ uninjured shoulders, and the Constant and ASES shoulder scores, which were evaluated 6 months after surgery.

Results

All fractures displayed clinical union within 13 weeks postoperatively. The mean union time was 9.2 weeks (range 7–13 weeks). At the time of union, the CC distances on the affected shoulders were on average 0.9 mm (range 0–1.6 mm) longer than the unaffected shoulders. At 6 months after surgery, the Constant and ASES scores were on average 93.4 (72–100) and 91.5 (75–100), respectively. No complications related to the fixation loops, musculocutaneous nerve injuries, or fractures of coracoid or clavicle were recorded. One case of surgical wound dehiscence was observed due to superficial infection. Enlargement of the clavicle drill hole without migration of the buttons was observed in 9 out of 16 cases at a follow-up time of at least 30 months after the original operation.

Conclusions

Modified CC stabilization using bidirectional CC loops seated behind the CA ligament is a simple surgical technique that naturally restores stability to the distal clavicle fracture. It also produces predictable outcomes, a high union rate, good to excellent shoulder function, and a low complication rate. The buttons and suture loops were routinely removed in a second operation in order to prevent late stress fracture of the clavicle.

     

Surgical excision of ununited hook of hamate fractures via the carpal tunnel approach

Introduction

Direct excision of a symptomatic ununited hook of hamate fracture is the gold standard, most frequently via a Guyon space approach. The open carpal tunnel approach is another option, which has not previously been commonly considered and not reported in a peer review journal. Our study aims to highlight the carpal tunnel approach as a successful technique in a consecutive series of ununited hook of hamate fractures.

Patients and methods

Seven patients (all male and mean age 30.7 years) were reviewed with symptomatic ununited fractures following a period of cast immobilization. All the patients operated on underwent excision of the hook of hamate fragment via the open carpal tunnel approach.

Results

All patients successfully returned to their pre-injury level of functioning after 8–12 weeks and there were no complications.

Conclusions

Our study highlights the open carpal tunnel approach as a successful technique for open excision of symptomatic ununited hook of hamate fractures, because of its familiarity, ease of performance, excellent visualization and low morbidity.Level of Evidence IV Case Series.     

Axial plane analysis of Lenke 1A adolescent idiopathic scoliosis as an aid to identify curve characteristics

Background context

Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional (3D) deformity of the spine involving deviations in the frontal plane, modifications of the sagittal profile, and rotations in the transverse plane. Although Lenke classification system is based on 2D radiographs and includes sagittal thoracic and coronal lumbar modifiers, Lenke et al. suggested inclusion of axial thoracic and lumbar modifiers in the analysis.

Purpose

To analyze axial plane of Lenke 1A curves to identify curve characteristics.

Study design

Retrospective study.

Patient sample

Seventy patients (49 women, 21 men) with Lenke Type 1A idiopathic scoliosis were analyzed.

Outcome measures

Coronal, sagittal, and axial parameters were measured from plain radiographs that were obtained at initial medical examination of the patients.

Methods

Coronal and sagittal plane and whole spine segmental vertebra rotations from thoracic 1 to lumbar 5 were evaluated in 70 AIS patients with Lenke 1A curves by using Drerup method. Three different subgroups were identified according to magnitude and direction of lower end vertebra (LEV) rotation.

Results

In Group 1 (Lenke 1A1), the direction of LEV rotation was same with other vertebrae in the main curve and the magnitude of the LEV rotation was less than −0.5°. In Group 2 (Lenke 1A2), the rotation of LEV was between −0.5° and 0.5° and so was accepted as neutral. In Group 3 (Lenke 1A3), the rotation of LEV had opposite direction with vertebrae in the main curve and the magnitude of LEV rotation was more than 0.5°. The mean thoracic Cobb angle of patients with Lenke 1A idiopathic scoliosis was 51.1° (range 37°–80°), whereas the mean lumbar Cobb angle was 16.4° (range 0°–32°). The mean angle of trunk rotation of the patients was 5.7° (range 1°–16°). In terms of maximum thoracic vertebra rotation, the mean rotation angle of Lenke 1A idiopathic curves was −18.9° (range −(9.8°–44.7°)). The mean maximum lumbar vertebra rotation was 4.5° (range −7.2° to 15.1°).

Conclusions

Addition of axial plane analysis to conventional coronal and sagittal evaluations in patients with Lenke 1A curves may reveal inherent structural differences that are not apparent in single planar radiographic assessments and may necessitate a different surgical strategy.     

Clavicular Tunnel Complications after Coracoclavicular Reconstruction in Acute Acromioclavicular Dislocation: Coracoid Loop versus Coracoid Tunnel Fixation

BackgroundThe purpose of this study was to compare clavicular tunnel complications after coracoclavicular (CC) reconstruction between a coracoid loop fixation group and a coracoid tunnel fixation group. We hypothesized that clavicular tunnel complications would be more common in the coracoid loop group.MethodsThis retrospective study evaluated 24 patients who underwent CC reconstruction using coracoid tunnel fixation (n = 14) and coracoid loop fixation (n = 10). Radiographic measurements included the CC distance and clavicular tunnel diameter. Clavicular tunnel complications such as tunnel widening and clavicular tunnel fractures were investigated. Clinical outcomes were assessed using the American Shoulder and Elbow Surgeons Shoulder score and the University of California at Los Angeles Shoulder score.ResultsThe mean follow-up period was 17.5 months (range, 11–38 months). The final clavicular tunnel diameter and the increase in the clavicular tunnel diameter in millimeter and percentage were significantly greater in the coracoid loop group than in the coracoid tunnel group (all p < 0.05). Clavicular tunnel widening more than 100% was found in 5 patients, all belonging to the coracoid loop group. Clavicular tunnel fractures occurred in 3 patients (all in the coracoid loop group). Fracture was associated with severe tunnel widening (more than 100% increase). The mean value of the final clavicular tunnel diameter in patients with fractures was significantly larger than that in patients without (12.7 ± 3.3 mm vs. 8.4 ± 1.5 mm, p = 0.016).ConclusionsClavicular tunnel complications such as significant tunnel widening and fractures after CC reconstructions in acromioclavicular dislocations were common with the coracoid loop fixation technique. A greater clavicular tunnel widening and resultantly enlarged tunnel diameter might increase the risk of fracture through the clavicular tunnel.     

The (f)utility of flexion-extension C-spine films in the setting of trauma

Background

Flexion-extension radiographs are often used to assess for removal of the cervical collar in the setting of trauma. The objective of this study was to evaluate their adequacy. We hypothesized that a significant proportion is inadequate.

Methods

This was a retrospective review of C-spine clearance at a level 1 trauma center. A trauma-trained radiologist interpreted all flexion-extension radiographs for adequacy. Studies performed within 7 days of injury were considered acute.

Results

Three hundred fifty-five flexion-extension radiographs were examined. Ninety-five percent% of these studies were inadequate (51% because of the inability to visualize the top of T1, whereas 44% had less than 30° of angulation from neutral). Two hundred ten studies were performed acutely; of these, 97% were inadequate. When performed 7 days or longer from injury, 91% were inadequate.

Conclusions

Injury to the C-spine may harbor significant consequences; therefore, its proper evaluation is critical. The majority of flexion-extension films are inadequate. As such, they should not be included in the algorithm for removal of the cervical collar. If used, adequacy must be verified and supplemental radiographic studies obtained as indicated.     

The Munich Shoulder Questionnaire (MSQ): development and validation of an effective patient-reported tool for outcome measurement and patient safety in shoulder surgery

Purpose

In this retrospective study we investigated the clinical and radiological outcome after operative treatment of acute Rockwood III-V injuries of the AC-joint using two acromioclavicular (AC) cerclages and one coracoclavicular (CC) cerclage with resorbable sutures.

Methods

Between 2007 and 2009 a total of 39 patients fit the inclusion criteria after operative treatment of acute AC joint dislocation. All patients underwent open reduction and anatomic reconstruction of the AC and CC-ligaments using PDS? sutures (Polydioxane, Ethicon, Norderstedt, Germany). Thirty-three patients could be investigated at a mean follow up of 32±9?months (range 24?C56?months).

Results

The mean Constant score was 94.3±7.1 (range 73?C100) with an age and gender correlated score of 104.2%±6.9 (88-123%). The DASH score (mean 3.46±6.6 points), the ASES score (94.6±9.7points) and the Visual Analogue Scale (mean 0.5±0,6) revealed a good to excellent clinical outcome. The difference in the coracoclavicular distance compared to the contralateral side was <5?mm for 28 patients, between 5-10?mm for 4 patients, and more than 10?mm for another patient. In the axial view, the anterior border of the clavicle was within 1?cm (ventral-dorsal direction) of the anterior rim of the acromion in 28 patients (85%). Re-dislocations occured in three patients (9%).

Conclusion

Open AC joint reconstruction using AC and CC PDS cerclages provides good to excellent clinical results in the majority of cases. However, radiographically, the CC distance increased significantly at final follow up, but neither the amount of re-dislocation nor calcifications of the CC ligaments or osteoarthritis of the AC joint had significant influence on the outcome.

Level of evidence

Case series, Level IV     

Biomechanical analysis of acromioclavicular joint dislocation repair using coracoclavicular suspension devices in two different configurations

BackgroundThe best treatment option for some acromioclavicular (AC) joint dislocations is controversial. For this reason, the aim of this study was to evaluate the vertical biomechanical behavior of two techniques for the anatomic repair of coracoclavicular (CC) ligaments after an AC injury.ResultsGroup I reached a maximum force to failure of 635.59 N (mean 444.0 N). The corresponding force was 939.37 N (mean 495.6 N) for group II and 533.11 N (mean 343.9 N) for group III. A comparison of the three groups did not find any significant difference despite the loss of resistance presented by group III.ConclusionAnatomic repair of coracoclavicular ligaments with a double system (double tunnel in the clavicle and in the coracoid) permits vertical translation that is more like that of the acromioclavicular joint. Acromioclavicular repair in a “V” configuration does not seem to be biomechanically sufficient.     

Lower limb malrotation following MIPO technique of distal femoral and proximal tibial fractures

Objective

To determine the incidence of rotational malalignment in distal femoral and proximal tibial fractures using computed tomography (CT) scanograms following indirect reduction and internal fixation with the minimally invasive percutaneous osteosynthesis (MIPO) technique.

Design

Prospective Cohort.

Setting

Level I Trauma Centre.

Patients/Participants

A total of 27 consecutive subjects, and 14 proximal tibia and distal femur fractures.

Intervention

All patients underwent indirect reduction and internal fixation with a MIPO plating system. A CT scanogram to measure rotational malalignment between the injured and non-injured extremity was then undertaken.

Main outcome measure(s)

Femoral anteversion angles and tibial rotation angles between the injured and non-injured extremities were compared. Malrotation was defined as a side-to-side difference of >10°.

Results

A total of 14 postoperative tibias and 13 femurs underwent CT scanograms. Three females and 11 males with an average age of 38.1 years sustained proximal tibia fractures and six females and seven males with an average age of 55.8 years sustained distal femur fractures. The difference between tibial rotation in the injured and the non-injured limbs ranged from 2.7 to 40.0° with a mean difference of 16.2° (p = 0.656, paired T-test). Fifty percent of the tibias fixed with MIPO plates were malrotated >10° from the uninjured limbs. The difference between femoral anteversion in the injured and non-injured limbs ranged from 2.0 to 31.3° with a mean difference of 11.5° (p = 0.005, paired T-test). A total of 38.5% of the distal femurs fixed with MIPO plates were malrotated >10° from the uninjured limb.

Conclusions

Following fixation of distal femoral and proximal tibial fractures, the incidence of malrotation was 38.5% and 50%, respectively. The difference of the mean measures was significant for femoral malrotation; however, statistical significance could not be demonstrated for tibial malrotation. The incidence of malrotation following MIPO plating in this study is much higher than that quoted in previous studies.     

Innovative use of single-incision internal fixation of distal clavicle fractures augmented with coracoclavicular stabilisation

Introduction

The management of displaced fractures of the distal clavicle remains controversial, particularly in younger patients where there is no consensus as to which surgical intervention is best. Each surgical method has unique surgical complications and rates of persistent pain and post-traumatic arthritis. We report an innovative surgical technique using a plate fixation augmented with minimally invasive tension slide coracoclavicular fixation using a cortical tenodesis button (8.5 mm).

Methods

A single-surgeon series, comprising of eleven cases, underwent retrospective review. A low-profile pre-contoured stainless steel plate that combines locking and non-locking options was used. Secondary fixation to the coracoid, through the plate, was achieved under fluoroscopic guidance eliminating the need for arthroscopy or exposure of the coracoid. An 8.5-mm cortical button loaded with a single FiberTape is inserted with fluoroscopic navigation, flipped under the coracoid and fixed to the plate. Patients followed a standardised rehabilitation protocol and clinical review assessing time to union, complications and Oxford Shoulder Scores.

Results

The mean age of the patients was 40 years, 82% male. The majority were day-case admissions with a mean follow-up of 18 months. Although a single patient requested plate removal due to lateral prominance, there were no revisions for implant failure and no surgical site infections or neurovascular injuries. All patients were reviewed at a minimum of 17 weeks and were progressing to union. Mean Oxford Shoulder Score was 43 (28–48, SD 6.5).

Conclusion

We consider this technique ideal for treating Neer type II distal clavicle fractures or fractures that have poor bone quality laterally, in which it can be difficult to achieve adequate screw fixation. The technique benefits from smaller tunnel diameter (3.7-mm spade-tip drill) and button length (8.5 mm). The procedure has a short learning curve and is both safe and time efficient.

Level of evidence

IV.

     

Facet joint contact pressure is not significantly affected by ProDisc cervical disc arthroplasty in sagittal bending: a single-level cadaveric study

Background context

Total disc arthroplasty is a motion-preserving spinal procedure that has been investigated for its impact on spinal motions and adjacent-level degeneration. However, the effects of disc arthroplasty on facet joint biomechanics remain undefined despite the critical role of these posterior elements on guiding and limiting spinal motion.

Purpose

The goal was to measure the pressure in the facet joint in cadaveric human cervical spines subjected to sagittal bending before and after implantation of the ProDisc-C (Synthes Spine Company, L.P, West Chester, PA, USA).

Study design

A biomechanical study was performed using cadaveric human cervical spines during sagittal bending in the intact and implanted conditions.

Methods

Seven C2–T1 osteoligamentous cadaveric cervical spines were instrumented with a transducer to measure the C5–C6 facet pressure profiles during physiological sagittal bending, before and after implantation of a ProDisc-C at that level. Rotations of the index segment and global cervical spine were also quantified.

Results

The mean C5–C6 range of motion significantly increased (p=.009) from 9.6°±5.1° in the intact condition to 16.2°±3.6° after implantation. However, despite such changes in rotation, there was no significant difference in the facet contact pressure during extension between the intact (64±30 kPa) and implanted (44±55 kPa) conditions. Similarly, there was no difference in facet pressure developed during flexion.

Conclusions

Although implantation of a ProDisc-C arthroplasty device at the C5–C6 level increases angular rotations, it does not significantly alter the local facet pressure at the index level in flexion or extension. Using a technique that preserves the capsular ligament, this study provides the first direct measurement of cervical facet pressure in a disc arthroplasty condition.     

Does catastrophic midline failure of upper thoracic lamina screws violate the spinal canal? A cadaveric biomechanical analysis using two lamina screw techniques

Background context

Lamina screws have been reported to be a biomechanically sound alternative to pedicle screws in the proximal thoracic spine. However, concerns have been raised that midline failure may result in a spinal canal breach.

Purpose

To evaluate the catastrophic failure of proximal thoracic lamina screws using two techniques for lamina screw purchase.

Study design

Biomechanical study with human cadaveric vertebrae.

Patient sample

Not applicable.

Outcome measures

Not applicable.

Methods

Nineteen fresh-frozen T1–T2 vertebrae were Dual energy X-ray absorptiometry scanned for bone mineral density. Caliper measurements of lamina thickness and lateral mass width for bicortical purchase were obtained. Ten specimens had right-to-left 26-mm lamina screws inserted entirely within the length of the lamina (unicortical). Nine specimens had right-to-left 42-mm lamina screws inserted as to extend the length of the lamina and breach the cortex behind the first and second ribs (bicortical). All screws were placed by experienced spine surgeons under fluoroscopic visualization using 4.5-mm cervicothoracic screws. Insertional torque was recorded while placing all implants and reported in “in-lbs.” Tensile loading to failure was performed with the force oriented in the parasagittal plane along the vertebral midline. Pullout loading was applied at a rate of 0.25 mm/s using an MTS 858 MiniBionix II System (MTS Systems, Inc., Minneapolis, MN, USA) with the maximum pullout strength (POS) recorded in Newtons. Video fluoroscopy was performed during midline pullout to evaluate screw failure and ascertain spinal canal breach. After testing, all specimens were visually inspected for spinal canal breach.

Results

Neither the unicortical nor the bicortical lamina screws violated the spinal canal during catastrophic midline failure. The ventral lamina cortex remained intact for both the lamina screw techniques. All of the unicortical lamina screws resulted in dorsal avulsion of the spinous process and lamina. All nine bicortical lamina screws separated the dorsal lamina from the ventral but were able to maintain lateral mass purchase. The peak insertional torque for both lamina screw techniques was not significantly different (p=.20). However, bicortical lamina screw POS (584.8±150.2 N) was significantly greater than unicortical lamina screw POS (455.6±100.2 N) (p=.04). Bone mineral density showed a moderate correlation with unicortical (r=0.67) and bicortical (r=0.47) lamina screw POS.

Conclusion

Our results suggest that catastrophic midline failure of lamina screws does not violate the spinal canal. Of the two techniques tested, bicortical lamina screws have a biomechanical advantage. Lamina screws present a viable option for instrumenting the proximal thoracic spine.     

Correction of malalignment in proximal femoral nailing—Reduction technique of displaced proximal fragment

Introduction

External rotation, abduction, and flexion of the proximal fragment in proximal femoral fracture are one of the main obstacles in nailing. We introduced simple surgical technique using a long hemostatic forceps to achieve fracture reduction and to facilitate preparation of the nail entry site.

Method

Using this reduction method, 16 patients with displaced subtrochanteric or proximal femoral shaft fracture were treated through cephalomedullary or femoral nailing between January 2005 and May 2007.

Results

The difference of the neck-shaft angle in the AP view compared to the normal side was 2.2° (range, 0-5°). Anterior angulation in the lateral view was 1.6° (range, 0-15°). One case of malunion was caused by too anterior nail insertion in the lateral view. Bone union was achieved in all cases with an average consolidation time of 5.1 months (range, 3-9 months).

Conclusion

A simple reduction technique using readily available instruments in the operating room (hemostatic forceps) is quite useful in reducing proximal femoral fragments in cephalomedullary or femoral nailing.     

Comparison of outcomes after triceps split versus sparing surgery for extra-articular distal humerus fractures

Objectives

To compare elbow range of motion (ROM), triceps extension strength, and functional outcome of AO/OTA type A distal humerus fractures treated with a triceps-split or -sparing approach.

Design

Retrospective review.

Setting

Two level one trauma centres.

Patients

Sixty adult distal humerus fractures (AO/OTA 13A2, 13A3) presenting between 2008 and 2012 were reviewed. Exclusion criteria removed 18 total patients from analysis and three patients died before final follow-up.

Intervention

Patients were divided into two surgical approach groups chosen by the treating surgeon: triceps split (16 patients) or triceps sparing (23 patients).

Main outcome measurements

Elbow ROM and triceps extension strength testing were completed in patients after fractures had healed. All patients were also given the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire.

Results

Compared to the triceps-split cohort, the triceps-sparing cohort had greater elbow flexion (sparing 143 ± 7° compared to split 130 ± 12°, p = 0.03) and less extension contracture (sparing 6 ± 8° compared to split 23 ± 4°, p < 0.0001). Triceps strength compared to the uninjured arm also favoured the triceps-sparing cohort (sparing 88.9 ± 28.3% compared to split 49.4 ± 17.0%, p = 0.007). DASH scores were not statistically significant between the two cohorts (sparing 14.5 ± 12.2 compared to split 23.6 ± 22.3, p = 0.333).

Conclusions

A triceps-sparing approach for surgical treatment of extra-articular distal humerus fractures can result in better elbow ROM and triceps strength than a triceps-splitting approach. Both approaches, however, result in reliable union and similar functional outcome.

Level of evidence

Level III.