Optimal pin position in supraacetabular external fixation.

BACKGROUND: This study focuses on (i) the length of the intraosseous part of the supraacetabular pin using the insertion technique from the spina iliaca anterior inferior to the cortical part of the incisura ischiadica major, (ii) the angle of insertion of the supraacetabular pin in the transversal plane and (iii) gender-specific differences of the measured results. METHODS: Images of uninjured pelves from 49 patients (64-line computed tomography scanner) were evaluated, and virtual external fixator pins were positioned using a three-dimensional reconstructions of computed tomography scans. The length of the pins and the insertion angle were investigated. Descriptive statistics were used, and gender-specific differences were calculated. A P-value of <0.05 was considered statistically significant. RESULTS: The results showed significant differences between male and female pelves concerning both pin length and insertion angel. For male pelves, the mean screw length was 82.7 mm (SD 5.1; range 72.9-94.3). For females, this was statistically significantly shorter (P ≤ 0.001), with an average of 74.1 mm (SD 5.0; range 63.1-81.9). In the male subgroup, the insertion angle was a mean of 22.6° (SD 3.4; range 12.4-31.8), and the female pelves had an average angle of 19.7° (SD 4.0; range 11.7-24.5). These values differed statistically significantly (P = 0.0032). CONCLUSION: Based on our measurements, we can confirm that both the length of the Schanz screws and the angle of insertion for the supraacetabular external fixator show a statistically significant difference between males and females.

A Novel Surgical Technique for Fixation of Recurrent Acromioclavicular Dislocations: AC Dog Bone Technique in Combination with Autogenous Semitendinosus Tendon Graft.

Various surgical techniques have been described for the fixation of acromioclavicular (AC) dislocations. However, recurrent dislocation is one of the main complications associated with the majority of these techniques. We report a case of postoperative AC joint redislocation. In order to overcome recurrent dislocation after revision surgery, a reconstruction of the conoid and trapezoid ligament with the use of a free tendon graft in combination with a FiberTape was provided within a novel surgical technique. After 12 months, the patient was very satisfied with the functional outcome. The patient achieved excellent results in the Constant (98 points), SPADI (0 points), and QuickDASH score (0 points). The described technique results in an anatomic reconstruction of the AC joint. The nonrigid nature of the intervention seems to restore the normal arthrokinematics by reconstructing the coracoclavicular ligaments with an autograft which is then protected by the AC Dog Bone artificial ligaments during the healing period. The arthroscopic approach to the AC joint with minimal exposure reduces the risks and complications of the intervention. This is the first case in literature that utilizes the artificial dog bone ligament securing the autograft in an anatomic AC reconstruction.

Computer-aided analysis of radial head morphometry.

Operative treatment of displaced and comminuted radial head fractures involves internal fixation with plates and screws in cases where reconstruction is possible and replacement with a radial head prosthesis when comminution renders the radial head unreconstructable. The purposes of this study were to evaluate the morphometry of the radial head using a modern technique and to compare the findings with several commercially available radial head prostheses. Computed tomography scans of 30 cadaveric elbows and 3-dimensional reconstructions were used to analyze the morphometry of the proximal radius. Results were compared with the manufacturer data of several radial head prostheses. Mean diameter of the radial head at the level of the fovea was 19±1.58 mm (range, 15.82-21.81 mm) in the anteroposterior plane and 18.62±1.78 mm (range, 15.48-22.21 mm) in the radioulnar plane. Mean diameter of the radial head at its widest part was 23.15±1.94 mm (range, 19.45-26.49 mm) in the anteroposterior plane and 22.44±1.73 mm (range, 19.64-25.44 mm) in the radioulnar plane. Mean diameter of the radial head at the level of the head-neck junction was 15.42±1.59 mm (range, 11.80-18.46 mm) in the anteroposterior plane and 14.75±1.39 mm (range, 12.32-17.31 mm) in the radioulnar plane. Statistically significant sex differences existed in the maximum diameter of the radial head, the diameter at the level of the head-neck junction, and the length of the radial head. Currently available radial head prostheses cover the range of sizes encountered. Products with a choice of head and stem sizes in any combination are preferable. In unstable elbow fractures, correct implant size is an important factor to avoid subluxation of the radial head (Mason type IV fractures) if collateral ligaments are sufficient.

Percutaneous fixation of acetabular fractures: computer-assisted determination of safe zones, angles and lengths for screw insertion.

INTRODUCTION: Percutaneous retrograde screw fixation for acetabular fractures is a demanding procedure due to the complex anatomy of the pelvis and the varying narrow safe bony corridors. Limited information is available on optimal screw placement and the geometry of safe zones for screw insertion in the pelvis. METHODS: Three-dimensional reconstructions of 50 consecutive CT scans of polytrauma patients (35 males, 15 females) were used to introduce three virtual CAD bolts (representing screws) into the anterior column (superior ramus of the pubic bone), posterior column (the ischial bone) and the supraacetabular region, as performed during percutaneous screw fixation. The three-dimensional (3D) position of these screws was evaluated with a computer software (MIMICS) after virtual optimal insertion. The 3D position, the narrowest zone and the distance to the hip joint of the two columns and the supraacetabular region were defined. RESULTS: The mean maximal screw length for the three virtual screws measured between 107.4 and 148 ± 18.7 mm. The narrowest zone of the pelvic bone (superior pubic ramus) had a width of 9.2 ± 2.4 mm. The average distances between the bolts and the hip joint were 3.9 and 19.4 ± 7.4 mm. For the anterior column (superior pubic ramus) screw, the mean lateral angle to the sagittal midline plane was 39.0 ± 3.2° and the mean posterior angle to the transversal midline plane was 15.1 ± 4.0°. The mean supraacetabular screw angles measured 22.4 ± 3.4° (medial), 35.3 ± 4.6° (cranial) and the mean angles for the ischial screw were 12.0 ± 5.4° (posterior) and 18.4 ± 4.0° (lateral). CONCLUSIONS: The zones for safe screw positioning are very narrow, making percutaneous screw fixation of the acetabulum a challenging procedure. The predefined angles for the most frequently positioned percutaneous screws may aid in preoperative planning, decrease operative and radiation times and help to increase safe insertion of screws.

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.

Three-dimensional morphometry of the proximal ulna: a comparison to currently used anatomically preshaped ulna plates.

BACKGROUND: Anatomically preshaped plates are increasingly used for stabilization of comminuted olecranon and Monteggia fractures. The purposes of this study were to investigate the morphology of the proximal ulna and to compare morphologic findings with geometry of 4 preshaped ulna plates. MATERIALS AND METHODS: Forty human elbows (mean age, 68 years; range, 21-98 years) were measured by 2 independent observers using 64-slice computed tomography scans and 3-dimensional measuring software. RESULTS: Measurements showed a mean dorsal hook angle of 95.3° ± 9.0° (range, 74.7°-110.8°) with gender-specific differences (mean, 92.2° ± 8.1° in men and 98.3° ± 8.9° in women; P = .029); a mean distance from the tip of the olecranon to the proximal edge of the ulna of 24.7 ± 2.7 mm (range, 20-30.5 mm) with gender-specific differences (P = .00068); a mean varus angulation of 14.3° ± 3.6° (range, 5.8°-21.2°); and a mean anterior angulation (proximal ulna dorsal angulation) of 6.2° ± 2.7° (range, 1.0°-11.2°). The investigated plates offered a tolerable (± standard deviation) hook angle in 25% to 68%, an appropriate varus angulation in 0% to 20%, and an adequate anterior angulation in 23% to 88%. The intraclass correlation coefficient was between 0.74 and 0.91. CONCLUSION: The proximal ulna has a gender-specific and variable morphology. Some currently used anatomically preshaped proximal ulna plates differ significantly from these morphologic findings. In cases where reduction is not exactly possible, application of an "anatomically preshaped" plate may result in poor reduction. Especially in case of Monteggia fractures with instability of the radiocapitellar joint, surgeons could be misguided by plates that do not incorporate anterior angulation, resulting in subluxation of the radial head on the capitellum.

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.

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.

A morphometrical study of the medullary cavity of the ulna referred to intramedullary nailing.

Intramedullary fixation is preferred for osteosynthesis in the case of long bone fractures; but the problem of the nails' adjustment to the anatomical needs remains. About 80 cadaveric ulnae were examined to elucidate the curvature of the medullary cavity, the point of varus angulation, the thickness of the radial and ulnar cortical bone and the diameter of the medullary cavity at that point. Furthermore, the point of varus angulation of the posterior border was compared to that of the medullary cavity, to evaluate if it allows any conclusion to the curvature of the medullary cavity. The point of varus angulation of the medullary cavity ranged from 45 to 110 mm (mean 71.02), its angle from 4 to 13.5 grade (mean 8.95). At this point, the thickness of the cortical bone on the radial side was between 2.5 and 7 mm (mean 4.44) and ulnar between 2 and 8 mm (mean 4.37). The diameter ranged from 4 to 10.5 mm (mean 6.96). The point of varus angulation of the posterior border was between 65 and 110 mm (mean 85.88) and differs from that of the medullary cavity observed between 45 and 110 mm (mean 71.02). The point of varus angulation of the posterior border and the medullary cavity differs from 1 to 60 mm and it is found in most cases to be more distal than the point of varus angulation of the medullary cavity so the palpable posterior border allows no reliable conclusion of the curvature of the medullary cavity.

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.