Does the IOFIX improve compression in ankle fusion?

BACKGROUND: The new IOFIX is an intra-osseous fixation device comprising an "X-post" through which a lag screw passes to apparently improve force distribution across an arthrodesis. We conducted a novel human cadaveric study. Our null hypothesis was no difference in force exists in an ankle arthrodesis model stabilized with the IOFIX or a conventional single lag screw. METHOD: In ten cadaver ankles a pressure transducer was compressed as an IOFIX and standard single lag screws were alternately compared. RESULTS: The median average force created by the IOFIX was 3.95kg and 2.4kg for the single conventional lag screw (p⩽0.01). The IOFIX improved contact area across the arthrodesis with a median average of 3.41cm(2) compared with 2.42cm(2) in the lag screw group (p⩽0.03). CONCLUSION: Our results suggest an IOFIX improves force distribution across an ankle arthrodesis compared with a single conventional lag screw.

The risk of injury to the anterior tibial artery in the posterolateral approach to the tibia plateau: a cadaver study.

BACKGROUND: Posterolateral tibial plateau shear fractures often require buttress plating, which can be performed through a posterolateral approach. The purpose of this study was to provide accurate data about the inferior limit of dissection. METHODS: Forty unpaired cadaver adult lower limbs were used. The anterior tibial artery was identified because it coursed through the interosseous membrane. The perpendicular distance from the lateral joint line and fibula head to this landmark was measured. RESULTS: The anterior tibial artery coursed through the interosseous membrane at 46.3 ± 9.0 mm (range 27-62 mm) distal to the lateral tibial plateau and 35.7 ± 9.0 mm (range 17-50 mm) distal to the fibula head. CONCLUSIONS: Displaced posterolateral tibial plateau fractures require anatomic reduction and stabilization with a buttress plate. This can be achieved by gaining access to the posterolateral tibial cortex. The distal limit of this dissection can be as little as 27 mm distal to the lateral tibial plateau. Dissection in this region should be carried out with caution.

Radiological landmarks for the safe extra-capsular placement of supra-acetabular half pins for external fixation.

PURPOSE: Low anterior external fixators are constructed by placing half pins in the dense bone tunnel of the supra-acetabular region in an anterior to posterior direction. Although the placement of these pins is extra-articular, they may still breach the hip capsule on the anterior inferior iliac spine and thus be intra-capsular. We aim to provide radiological markers for the most superior fibres of the capsule to allow safe extra-capsular pin placement within the supra-acetabular bone tunnel. METHODS: Thirteen cadaveric pelves were used for this study. The supra-acetabular bone tunnel was visualised with an image intensifier. The proximal most fibres of the hip joint capsule were marked with a K-wire so that their relation to the bone tunnel could be clearly seen on the images. Once all images were acquired they were calibrated and analysed to estimate the dimensions of the supra-acetabular bone tunnel and the reflection of the hip capsule. RESULTS: The median height of the bone tunnel was 23.6 mm (18.9-33.2) and maximum width was 11.4 mm (7.6-16.3). The inferior margin of the bone tunnel was 6.7 mm (1.1-14.5) superior to the acetabular dome, and the most proximal fibres of the capsule were 9.3 mm (4.7-6.1) superior to the acetabular dome. The inferior portion of the tunnel was 3.7 mm (0.3-8.9) within the joint. CONCLUSION: Half pins for the construction of a pelvic external fixator should be placed in the upper half of the supra-acetabular bone corridor to minimise the risk of intra-capsular placement.

Drilling, not a benign procedure: laboratory simulation of true drilling depth.

INTRODUCTION: Drilling is an integral part of almost all boney operations. Various anatomical structures coursing close to the bone are at risk if the drill bit projects beyond the far cortex. Aim of this study was to evaluate and quantify the depth to which surgeons over drill beyond the far cortex. MATERIALS AND METHODS: During an AO course 153 (41 females, 112 males) surgeons and physicians were invited to participate in this study. Each participant performed 3 bicortical drillings on generic artificial bone. Polystyrene plates were mounted on the far cortex of the bone to allow for exact measurement of the over penetration of the drill bit. RESULTS: A total of 462 bicortical drilling manoeuvres were analysed. The average projection of the drill bit beyond the far cortex was 6.31 mm. No significant statistical correlation was noted between the specialty or the experience of the participant and depth of over drilling. CONCLUSIONS: It is remarkable that the mean and the range of far cortex over-penetration was quite similar amongst surgeons of differing grades and experience. The results of this study should return to mind to pay attention when drilling particularly in anatomical sites where nerve and vessels coursing close to the far cortex.

Anatomical structures at risk with the proud retrograde femoral nail.

BACKGROUND: Post-operative knee pain is common following retrograde nailing, with its etiology often multifactorial although a well-established cause is nail protrusion from the intercondylar notch. The aim of this study was to assess the structures at risk if the nail is left proud of the femoral articular surface. METHODS: A retrograde femoral nail (Synthes Distal Femoral Nail) was inserted into the distal femur of 15 cadaveric lower limbs using the standard technique. The nail was left 10 mm proud of the articular surface and locked in this position. The knee was then put through a full range of movement while recording the intra-articular structures that came into contact with the distal end of the nail as well as the position of the knee when this occurred. This was repeated with the nail 5 mm proud. RESULTS: With the nail 10 mm proud, it impinged on the anterior horn of the medial meniscus in 14 cases and the anterior horn of the medial meniscus as well as the tibial insertion of the ACL in one case at 15° of flexion. At 70° of flexion the nail came into contact with the distal margin of the patellar articular surface in the midline in all 15 cases. With the nail 5 mm proud, it impinged on the anterior horn of the medial meniscus in seven cases and the tibial insertion of the ACL as well as the anterior horn of the medial meniscus in eight cases as the knee was brought into full extension. In flexion the distal margin of the patellar articular surface in the midline came into contact with the nail at 70° of flexion in all 15 cases. CONCLUSION: Correct positioning of a retrograde femoral nail is of paramount importance to avoid further iatrogenic injury to intra-articular structures.

Is plating of mid-shaft clavicular fractures possible with a conventional straight 3.5 millimeter locking compression plate?

OBJECTIVES: Current literature describes improved clinical outcomes and a minor rate of pseudoarthrosis following operatively treated clavicular fractures. We investigated the feasibility of using a standard 3.5 mm AO locking compression plate (LCP) of adequate length for the stabilisation of mid-shaft fractures of the clavicle. METHODS: The length and acromial and diaphyseal curvature depths were measured in 49 cadaveric clavicles. We then assessed how well the 6, 7, 8 and 9-hole plates fit on the clavicles. RESULTS: The mean clavicular length was 155±12 mm, with a mean acromial curvature of 18.1±3.7 mm and a mean diaphyseal curvature of 12 mm±4 mm. The optimum plate for the clavicle was a 7-hole LCP, providing adequate fixation in 48 of the 49 clavicles. CONCLUSION: The described technique for plate osteosynthesis of the clavicle with AO locking compression plate is feasible and results in a biomechanically strong construct for mid-shaft fractures. With the use of a locking plate, comminuted fractures may be bridged without a reduction in the strength of the construct.

The risk of nerve injury with minimally invasive plate osteosynthesis of distal fibula fractures: an anatomic study.

AIM: The aim of our study was to identify the structures which may be at risk of injury when using a minimally invasive technique for the osteosynthesis of the lateral malleolus and the influence of the size of the implant on the frequency of injury to these structures. METHOD: Forty plates were percutaneously inserted in 20 cadaveric legs. The region around the plate was then dissected to examine the relation of nerves and soft tissues to the plate. RESULTS: The superficial peroneal nerve was in direct contact with the plate in 11 of the 20 cases (55%) of the 10 hole plates. We encountered only one case of the superficial peroneal nerve skirting the proximal edge of a 6 hole plate (p = 0.0164). CONCLUSION: Consequently we recommend meticulous attention is paid to the dissection of soft tissues in both the proximal and distal incisions. The length of the plate may be checked with intraoperative imaging prior to its insertion, and the site of both proximal and distal incisions may be marked on the skin. After careful dissection down to the bone, preserving nerves and tendons, the periosteal elevator should be introduced both from the proximal as well as the distal incisions to prepare the extra-periosteal tunnel for the insertion of the plate, in order to avoid the entanglement of the superficial peroneal nerve with the metal work, particularly in plates of longer than six holes.

The risk injury to the posterior interosseous nerve in standard approaches to the proximal radius: a cadaver study.

PURPOSE: The aim of this study was to provide guidance on the safe zones for the exposure of the proximal radius by measuring the distance from the PIN to various anatomical landmarks in the proximal forearm in pronation and supination. METHODS: Twenty cadaveric arms were used for this study. On the anterior aspect of the forearm, the distance between insertion of the biceps tendon and the arcade of Frohse as well as the shortest distance between the PIN and the ulnar aspect of the radial neck were measured. On the posterior aspect of the forearm, the shortest distance between the PIN and the ulnar border of the interosseous membrane was measured at 30 and 50 mm distal to the articular surface of the radial head. RESULTS: The distance between the PIN and ulnar aspect of the radial neck had a mean of 21.6 mm in supination and 13.3 mm in pronation. The distance between the radial tuberosity and the arcade of Frohse was 18.6 mm. The mean distance between the PIN and the radial border of ulna at 30 mm distal to the articular surface of the proximal radius was 12.3 mm in supination and 22.3 mm in pronation. At 50 mm distal to the articular surface of the proximal radius the mean distance was 8 mm in supination and 16.2 mm in pronation. CONCLUSIONS: The course of this nerve is variable as it winds around the radial neck within the belly of the supinator muscle. Safe distances for dissection have been presented in our study.

Accuracy of anterolateral versus posterolateral subtalar injection.

INTRODUCTION: Injections into the subtalar joint may be performed for diagnostic or therapeutic reasons. The anterolateral approach is most commonly utilised for this purpose. We evaluated the success of an intra-articular puncture by using the anterolateral in comparison to the posterolateral approach. METHODS: Sixty-eight cadaver adult feet were used for performing injections into the subtalar joint without fluoroscopic or ultrasound guidance. Methylene blue dye was infiltrated into 34 of the 68 subtalar joints through an anterolateral approach and into 34 through an posterolateral approach. An arthrotomy was then performed to confirm the placement of the dye within the joint. RESULTS: Twenty-three of the anterolateral injections (67.6%) were successful as were 31 of 34 (91.2%) of the posterolateral. The posterolateral approach showed a greater accuracy with a statistically significance (p = 0.016). CONCLUSION: Unintended peri-articular injection can cause complications and an unsuccessful aspiration can delay diagnosis. Comparing the anterolateral to the posterolateral approach with regards to the rate of successful intra-articular puncture of the subtalar joint without the use of imaging there is a greater accuracy with the PL with statistically significance.

Morphology of the tibialis anterior muscle and its implications in minimally invasive plate osteosynthesis of tibial fractures.

We examined the variation in the origin of the tibialis anterior muscle from the lateral aspect of the tibial shaft and interosseous membrane as well as the variation in the morphology of its musculotendinous junction. Forty cadaveric lower leg specimens (20 right and 20 left) were dissected to reveal the anterior compartment. The origin of the tibialis anterior muscle and its relation to the lateral tibial shaft and interosseous membrane were determined. The position of the musculotendinous junction relative to the medial malleolus was also measured. Tibial length ranged from 29.5 to 45 cm (mean, 36.5+/-3.1 cm). The distal limit of the muscle origin was 5.9 to 20.5 cm (mean, 12.1+/-3.3 cm) from the tip of the medial malleolus. The distance between the musculotendinous junction and the medial malleolus ranged from 1.4 to 10.8 cm (mean, 6.1+/-1.9 cm). The attachment of the muscle belly ends between 15.3 and 31.8 cm (mean, 24.4+/-4.1 cm) distally from the joint line at the knee. There was no statistical correlation between tibial length and muscle morphology.This variation warrants consideration in the percutaneous insertion of screws in the distal end of long plates, as the neurovascular bundle may be injured in patients with a shorter muscle belly. We advocate an open distal approach to protect the neurovascular bundle during insertion of the plate and distal screws.

Computer-assisted 3-dimensional anthropometry of the scaphoid.

Scaphoid fracture fixation using a cannulated headless compression screw and the Matti-Russe procedure for the treatment of scaphoid nonunions are performed routinely. Surgeons performing these procedures need to be familiar with the anatomy of the scaphoid. A literature review reveals relatively few articles on this subject. The goal of this anatomical study was to measure the scaphoid using current technology and to discuss the findings with respect to the current, relevant literature.Computed tomography scans of 30 wrists were performed using a 64-slice SOMATOM Sensation CT system (resolution 0.6 mm) (Siemens Medical Solutions Inc, Malvern, Pennsylvania). Three-dimensional reconstructions from the raw data were generated by MIMICS software (Materialise, Leuven, Belgium). The scaphoid had a mean length of 26.0 mm (range, 22.3-30.7 mm), and men had a significantly longer (P<.001) scaphoid than women (27.861.6 mm vs 24.561.6 mm, respectively). The width and height were measured at 3 different levels for volume calculations, resulting in a mean volume of 3389.5 mm(3). Men had a significantly larger (P<.001) scaphoid volume than women (4057.86740.7 mm(3) vs 2846.56617.5 mm(3), respectively).We found considerable variation in the length and volume of the scaphoid in our cohort. We also demonstrated a clear correlation between scaphoid size and sex. Surgeons performing operative fixation of scaphoid fractures and corticocancellous bone grafting for nonunions need to be familiar with these anatomical variations.

Anatomical basis of the risk of radial nerve injury related to the technique of external fixation applied to the distal humerus.

PURPOSE: Stabilization of humeral shaft and elbow fractures can be achieved with an external-fixator. Reports about nerve injuries associated with this procedure are rare in literature. Purpose of this anatomical study was to examine the relation of the radial nerve to distal humeral half pins. METHODS: Percutaneous insertion of external-fixator half pins was performed in 20 upper limbs of 20 cadavers, according to established technique, laterally in the distal humerus. RESULTS: Dissection of the upper limbs showed radial nerve injury in four of the 40 placed half pins. The proximal half pin impaled the nerve in one case and the distal half pin in three cases. Moreover the nerve was directly in contact with the pins in nine cases (five proximally, four distally). CONCLUSIONS: Insertion of external-fixator half pins in the distal humerus can easily injure the radial nerve. Thus we advocate a larger skin incision, blunt dissection to the lateral cortex of the humerus and retraction of soft tissue during half pin insertion.

The percutaneous antegrade scaphoid fracture fixation--a safe method?

INTRODUCTION: The object of this study was to assess the risk of injury to tendons, nerves and vessels in percutaneous antegrade scaphoid fracture fixation. METHODS: Forty cadaveric forearms were used in this study. A guide wire for cannulated headless compression screws was inserted percutaneously in each scaphoid according to established surgical technique. RESULTS: No nerve or vessel injuries were observed. Tendons however were injured in 5 out of the 40 specimens. This included the extensor pollicis longus tendon in two specimens, the extensor carpi radialis tendon in two specimens and the extensor digitorum tendon in one specimen. CONCLUSIONS: Soft tissue injuries may be avoided by extending the skin incision and performing blunt dissection down to guide wire and screw entry point. In this manner, dorsal antegrade fixation of scaphoid fractures by using cannulated headless compression screws can be considered to be a safe and reliable technique for fixation of scaphoid fractures.

Frequency of instrument breakage during orthopaedic procedures and its effects on patients.

BACKGROUND: While breakage of an orthopaedic instrument is a relatively rare occurrence, orthopaedic surgeons need to be familiar with this complication and how to deal with it. Relatively little information about this subject has been published. METHODS: Every case of instrument breakage during orthopaedic procedures performed in two hospitals during a two-year period was documented prospectively. All patients were followed for a postoperative period ranging from twelve to thirty-six months, during which radiographs in two planes were made to assess changes in, or migration of, the broken object. RESULTS: During the observation period, 11,856 surgical procedures were performed in the two hospitals. The overall rate of instrument breakage was 0.35%. The broken piece was removed in five cases, and the broken instrument was left in situ in thirty-seven cases. During the follow-up period, none of the patients had any symptoms. CONCLUSIONS: In most cases, breakage of an orthopaedic instrument is not a problem. Any instance of instrument breakage should be fully documented in the surgical report.

Morphometric analysis of lister's tubercle and its consequences on volar plate fixation of distal radius fractures.

PURPOSE: The objective of this study was to measure the size and shape of Lister's tubercle and the depth of the extensor pollicis longus (EPL) groove to assess the risk of injury to the EPL tendon when performing volar plating of distal radius fractures. METHODS: The length and height of Lister's tubercle and the depth of the EPL groove were measured in 100 cadavers. RESULTS: The size of Lister's tubercle varied from 2 to 6 mm (average, 3.6 mm) in height radial to the tubercle and from 6 to 26 mm (average, 18.3 mm) in length. The depth of the EPL groove varied from 1 to 5 mm (average, 2.8 mm), with 63% being greater than 2 mm in depth. The height between the depth of the groove and the tip of the tubercle varied between 4 and 10 mm (average, 7.1 mm). No correlation was found with gender or right-side or left-side specimens. CONCLUSIONS: The individual and combined height of Lister's tubercle and the depth of the EPL groove are considerable. This fact needs to be considered when performing volar plating of distal radius fractures because of the possibility that it might be difficult to determine precisely the presence and amount of past-pointing of the distal screws.

Various circular arc radii of the distal volar radius and the implications on volar plate osteosynthesis.

The purpose of this anatomical study was to explore the different circular arc radii of the distal volar radius and provide more detailed anatomic information that will further the understanding of volar plate osteosynthesis. The profiles of the volar distal radii of 100 cadaver specimens were measured with a common profile gauge. Profiles were copied onto paper and then matched to a best-fit circular arc template to determine the radius of curvature on the radial and ulnar sides of the distal volar radius. The mean circular arc radius of the distal volar surface was 2.6 cm (+/-1 cm, 1-6 cm) on the radial side and 2.3 cm (+/-1 cm, 1-6 cm) on the ulnar side. A significant difference (P<.01) was noted in the radii of curvature of the distal radius in 55% of the study population. In 37% of these cases, the circular arc radius flattens toward the ulnar side. In 63%, it flattens toward the radial side. This characteristic may lead to a false rotation position of the distal fracture fragment following volar plate osteosynthesis. In addition, suboptimal or incorrect plate position may result due to the discrepancy between the plate radius of curvature and the radius of curvature of either the radial or ulnar volar radius.

The anatomy of the proximal ulna.

The posterior border of the ulna is the most important bony landmark for all dorsal surgical approaches and the guideline for open reduction, internal fixation of displaced comminuted fractures of the proximal ulna. We examined 74 cadaveric specimens to evaluate the anatomy of the proximal ulna, especially the course of the posterior border, the point of varus angulation, the width of the shaft, and the relationship of the posterior border to the interosseous and anterior ones. In 63 specimens, the mean point of varus angulation was 85.4 mm, and the average angulation angle was 17.7 degrees. In 11 specimens, the posterior border was either radially bowed or the bow was poorly defined and not localized to a specific area along the length of the bone. In conclusion, the variations of the proximal ulna have to be considered if dorsal plates and intramedullary screws are used.

Primary transection of the superficial peroneal nerve resulting from a distal fibula fracture.

Although a superficial peroneal nerve injury following an ankle fracture occurs frequently, primary transection of the nerve represents a rare injury. This report documents a case of primary lesion of the superficial peroneal nerve sustained following a Weber B bimalleolar ankle fracture. The nerve injury was diagnosed at the initial examination when the patient was found to have hypoesthesia in the area of her third to fifth toes. Subsequently an open reduction and internal fixation of the ankle fracture was done along with primary suture of the superficial peroneal nerve. At the patient's last follow-up at 8 months, the nerve had completely recovered and there was normal ankle range of motion. This report emphasizes the importance of a detailed neurologic examination including testing for sensation in patients with ankle fractures.

Anatomic variations of the musculotendinous junction of the soleus muscle and its clinical implications.

The soleus muscle, like the gastrocnemius, is a powerful plantarflexor muscle in the lower limb. The soleus muscle joins the aponeurosis of the gastrocnemius muscle to form the calcaneal (Achilles) tendon. While the basic anatomy of the soleus muscle has been previously described, no study has addressed the anatomical variations of its distal attachment. We found considerable anatomic variation in the distance between this musculotendinous junction and the most proximal point of the proximal edge. This distal measuring point was defined as the most proximal point of the proximal edge of the posterior surface of the calcaneal tuberosity. Eighty human cadaver specimens were preserved according to Thiel's method; we examined one limb from each cadaver, studying 80 lower extremities in total. Following careful dissection of the lower limb, we measured the distance between the distal point of attachment of the soleus muscle fibers (the musculotendinous junction) and the designated measuring point. Our findings were divided into three groups: Group 1 (10 cases, 12.5%), where the distance between the musculotendinous junction and the designated point on the calcaneal tuberosity was between 0 and 1 inches; Group 2 (56 cases, 70%), where the distance was between 1 and 3 inches; and Group 3 (14 cases, 17.5%), where the distance was greater than 3 inches. Detailed knowledge of the anatomic variations of the soleus muscle at its insertion point onto the calcaneal tendon has clinical implications in calcaneal tendon repair following rupture and in the planning of reconstructive surgery using soleus muscle flaps.