Juergen Koebke

Malunion of the clavicle causes significant glenoid malposition: a quantitative anatomic investigation

ObjectiveAn experimental cadaver model was used to assess the effects of a malunited fracture of the middle third of the clavicle on the functional anatomy of the shoulder joint.MethodAnatomic samples were prepared with simulated shortening and axial malposition of the clavicle. From these, alterations in glenoid fossa position were measured and depicted graphically.ResultsHealing of clavicle fractures with bony shortening leads to a ventromedialcaudal shift in glenoid fossa position. The following malpositions of the clavicle lead to the respective glenoid fossa positional changes: caudal deviation leads to a mediocaudal shift, cranial deviation leads to a dorsolateral shift of the glenoid fossa, ventral deviation causes a ventrolateral shift, dorsal deviation leads to mediocaudal shift of the fossa, cranial rotation leads to ventrolateral shift in fossa position, and caudal rotation leads to a dorsomedial shift in glenoid fossa position.ConclusionClinical implication of these data is that bony shortening in combination with caudal displacement leads to distinct functional deficits in abduction, particularly overhead motion. Using the above data, a vector model was created to calculate position of the glenoid fossa dependent on clavicle position/malposition. The model is a valuable tool to be used for planning open reduction and fixation of clavicular fractures or malunions.

Human Knee Joint Anatomy Revisited: Morphometry in the Light of Sex-Specific Total Knee Arthroplasty

This study investigates differences in the anatomy of male and female knee joints to contribute to the current debate on sex-specific total knee implants. Morphometric data were obtained from 60 human cadaver knees, and sex differences were calculated. All data were corrected for height, and male and female specimens presenting with an identical length of the femur were analyzed as matched pairs. Male linear knee joint dimensions were significantly larger when compared with females. When corrected for differences in height, medial-lateral dimensions of male knees were significantly larger than female; however, matched paired analysis did not prove these differences to be consistent. Although implant design should focus interindividual variations in knee joint anatomy, our data do not support the concept of a female-specific implant design.

Nasal, sellar, and sphenoid sinus measurements in relation to pituitary surgery

A study of 24 adult Caucasian cadavers was undertaken to assess and document the anatomical measurements within the nasal cavity and sphenoid sinus as routes of instrumentation utilized in sublabial transsphenoidal and endonasal endoscopic approaches. Five measurements were performed. The mean thickness of the anterior sellar wall was 0.8 ± 0.3 mm for both the sellar and presellar types of sinuses, respectively. Also, the mean thickness of the bony floor of the sellar type of sinus was 0.9 ± 0.4 mm. In addition, the mean depth of the sphenoid sinus was 13.6 ± 5.1 mm for the sellar type and 13.2 ± 3.9 mm for the presellar type of sinus. Furthermore, the mean distance between the suspinale (inferior–posterior edge of the anterior nasal spine) and the anterior sphenoid wall was 62.3 ± 4.6 mm for the sellar type of sinus (P < 0.05) and 60.6 ± 2.9 mm for the presellar type of sinus, while the distance between the subspinale and the anterior sellar wall had a mean value of 75.9 ± 6.3 mm for the sellar type of sinus (P < 0.05) and 73.8 ± 4.2 mm for the presellar type of sinus, with the distance of the sellar type sinus being greater for male specimens. Sphenoid sinus pneumatization was of a conchal type in 4%, presellar type in 28%, and sellar type in 68% of subjects examined. The results of the current study expand upon current anatomical knowledge and may be beneficial in the future refinement of surgical instrument design. Clin. Anat. 23:629–636, 2010.

Olecranon fracture fixation with a new implant: Biomechanical and clinical considerations

UNLABELLED This study aims to describe the first clinical results in the treatment of dislocated olecranon fractures with 2.2-mm, fine-threaded wires with a washer. Furthermore, in the second part of the article, the stability of these new implants has been compared to standard tension band wiring in a sawbone model. PATIENTS The radiological and clinical outcomes in 24 patients (mean age: 53.6 years) with 24 isolated Mayo type I and II fractures of the olecranon were evaluated in a prospective study after open reduction and internal fixation (ORIF) with a new fixation device (FFS; Orthofix). The quality of reduction with the implementation of 24 FFS constructions was compared with 24 tension band-wiring procedures performed by six different surgeons in a standard sawbone Mayo type IIa fracture model. Stability was tested in all constructs using a single cycle load to failure protocol (group I), cyclic loading for 300 cycles between 10 and 500 N (group II) and incremental sinusoidal loading from 10 to 200 N with an incremental increase of 10 N per cycle (group III) in a laboratory study. RESULTS The Morrey elbow score was excellent in 23 patients and good in one patient, with mean DASH score of 1.6. No implant migration, secondary dislocation or nonunion was observed. In the sawbone model, the quality of reduction was the same with the FFS implants compared to the tension band wiring in the sawbone model. Here, bending moments in all three groups showed no significant difference, whereas displacement at failure was significantly greater in the tension band-wiring group at a single cycle load (p=0.017). CONCLUSION Clinical results were comparable to tension band wiring and stability of the implants in the sawbone model was the same; thus, we conclude that the FFS technique can serve as an alternative treatment option for isolated olecranon fractures.

Morphometric and anthropometric analysis of Killian's triangle.

To determine the prevalence and the morphometric characteristics of Killians triangle and to examine their relationship with the anthropometric features of the person.

Arterial anatomy of the hallucal sesamoids.

The aim of this study was to analyze the arterial supply of the sesamoid bones of the hallux. Twenty‐two feet from adult cadavers were injected with epoxide resin or an acrylic polymer in methyl methacrylate (Acrifix®) and subsequently processed by two slice plastination methods and the enzyme maceration technique. Afterwards, the arterial supply of the sesamoid bones was studied. The first plantar metatarsal artery provided a medial branch to the medial sesamoid bone. The main branch of the first plantar metatarsal artery continued its course distally along the lateral side of the lateral sesamoid and supplied it. The supplying arteries penetrated the sesamoid bones on the proximal, plantar, and distal sides. The analysis and cataloging of the microvascular anatomy of the sesamoids revealed the first plantar metatarsal artery as the main arterial source to the medial and lateral sesamoid bones. In addition, the first plantar metatarsal artery ran along the lateral plantar side of the lateral sesamoid bone, suggesting that this artery is at increased risk during soft‐tissue procedures such as hallux valgus surgery. Clin. Anat. 22:755–760, 2009.

Bone density measurements of the paranasal sinuses on plastinated whole‐organ sections: Anatomic data to prevent complications in endoscopic sinus surgery

Objective/Hypothesis: Although anatomic data regarding the gross anatomy of the paranasal sinuses are available, severe complications of endonasal sinus surgery (ESS) are frequently reported. To understand and to avoid these complications, density of bony walls of the paranasal sinuses were studied in this report. Special attention was given to the analysis of the bone density in regions where minor and major complications occur in ESS. Methods: Thirty cadaver heads were embedded in epoxy resin. The plastic blocks were sectioned with a diamond‐coated wire saw into 1.0‐mm thick, parallel slices in axial, coronal, and sagittal planes for 10 specimens each. The slices were x‐rayed and scanned with a computerized image analyzing system. For each specimen the bone density in 12 regions of interest was measured. Results: Besides the macroscopic examination of the plastinated specimens, a bone density analysis based on x‐ray films is presented. Lowest bone density was found at the lateral wall of the sphenoid sinus (3.31 ± 0.99 mm aluminum [Al]); highest density was measured at the roof of the sphenoid sinus (12.91 ± 1.75 mm Al). Overall bone density in female specimens was 0.41 mm Al (mean) lower than in male specimens. Conclusions: This study is the first to use plastinated whole‐organ serial sections and bone density images for the analysis of potential complications in ESS. The illustration of regions with minor and major bone density of the paranasal sinuses and the ethmoid floor as presented in this study may help the novice sinus surgeon to minimize the risks of ESS and to avoid severe complications.

In-vitro comparison of the pullout strength of 3 different thoracic screw fixation techniques.

Summary of Background Data Dvorak et al in 1993 and Husted et al in 2003 reported 2 different screw fixation techniques at the thoracic spine as alternatives to transpedicular screws. So far, there is no investigation comparing the pullout stability of all 3 possible screw fixation techniques. Objective To evaluate the stability of possible alternatives for transpedicular screw fixation. Study Design A biomechanical human cadaver investigation of the transpedicular and 2 different extrapedicular techniques was performed in the form of a comparative pullout test. Materials and Methods Eighteen human vertebral bodies from Th7 to Th9 were harvested from 6 donors, dissected from surrounding tissue, and matched to 3 different fixation groups. As alternatives for transpedicular screw fixation, an extrapedicular supratransverse screw insertion from posterolateral and a tricortical screw fixation technique, penetrating the transverse process and reentering the vertebral body at the pedicle base were evaluated biomechanically. A unilateral screw fixation was performed in one of the described techniques. Axial pullout strength was measured using a Zwick Z50 servoelectric testing machine. Results The average pullout strength of the pedicle screws was 400 N, whereas the supratransverse and the pertransverse screw fixation resisted 370 N pullout force on average. There was neither a statistic significant difference between the pullout forces of the 3 groups nor a significant correlation of pullout strength and bone mineral density measured by quantitative computed tomography. Conclusions In-vitro pullout resistance of thoracic screw fixation does not differ significantly in intrapedicular and extrapedicular insertion techniques.

The Interspinous Spacer: A Clinicoanatomical Investigation Using Plastination

Purpose. The relatively new and less-invasive therapeutic alternative “interspinous process decompression device (IPD)” is expected to result in improved symptoms of neurogenic intermittent claudication (NIC) caused by lumbar spinal stenosis. The aim of the study was to analyze IPD position particularly regarding damage originating from surgical implantation. Methods. Anatomic assessments were performed on a fresh human cadaver. For the anatomic examination, the lumbar spine was plastinated after implantation of the IPDs. After radiographic control, serial 4 mm thick sections of the block plastinate were cut in the sagittal (L1–L3) and horizontal (L3–L5) planes. The macroanatomical positioning of the implants was then analyzed. The insertion procedure caused only little injury to osteoligamentous or muscular structures. The supraspinous ligament was completely intact, and the interspinous ligaments were not torn as was initially presupposed. No osseous changes at the spinal processes were apparent. Contact of the IPD with the spinous processes was visible, so that sufficient biomechanical limitation of the spinal extension seems likely. Conclusions. Minimally invasive IPD implantation with accurate positioning in the anterior portion of the interspinous place is possible without severe surgical trauma.

Influence of cementing the pin on resistance to fracture in hip resurfacing

BACKGROUND Since the introduction of modern hip resurfacing systems, there has been a controversy regarding the fixation of the centering pin in the femoral component. It has been suggested that cementing the pin may increase strength of the femoral neck. This in-vitro analysis investigated the influence of a cemented, femoral pin on resistance to fracture in the resurfaced hip. METHODS Five pairs of cadaveric, fresh-frozen femora underwent hip resurfacing (ASR™) using a high viscosity cementing technique. In one side of each pair only the inner surface of the implant was cemented, in the other side, cement was additionally hand-pressurized down the pinhole prior to implantation of the femoral component. Specimen were then mounted on a material testing machine and cyclic loading with increasing load steps was applied until fracture of the femoral neck. FINDINGS Fracture load was increased (P = 0.013) in the cemented pin group (Median = 4200 N) when compared with the cementless pin group (Median = 2800 N). The number of cycles to failure in the group with the cemented pin (Median = 8072) was likewise higher (P = 0.01) when compared to the group, in which the pin was not cemented (Median = 5906). INTERPRETATION Cementing the pin may provide additional fixation in hips with low bone mineral density or osteonecrotic lesions, as resistance to fracture could be improved in the presented in-vitro scenario. Although this was shown for a specific hip resurfacing system, this effect might be extrapolated to other, similar implant designs.