SMW Supplementum 193 - Swiss Medical Weekly

3 S SWiSS Med Wkly 2012;142(Suppl 193) · www.smw.ch Free communications
Results: Flexion and extension gap increased almost linearly with
increasing angle for all combinations of motion and location (p0.001).
Conclusion/ Relevance: If it is determined that the flexion gap is
tighter than the extension gap, increasing tibial slope more than
originally planned may not be recommended because it will influence
the size of the extension gap significantly. During surgery, the relative
difference between flexion and extension gap in size due to some
additional tibial slope may result from soft tissue and PCL release,
which perhaps automatically results from tibial bone cut
simultaneously.
FM5
Micro CT analysis of the subarticular bone structure
in the area of the talar trochlea
Silvan Zander1 , Hans Deyle2 , André Leumann3 ,
Magdalena Müller-Gerbl1 , Andrej M. Nowakowski3 1Anatomical Institute, University of Basel, Switzerland; 2Biomaterials Science Center, University of Basel, Switzerland; 3Orthopedic Department, University of Basel, Switzerland
Introduction: Certain regions of the talar trochlea are recognized as
exhibiting varying cartilage thickness and degrees of subchondral
bone mineralization. These changes have been attributed to the
long-term loading history. For the current study, we accepted the
hypothesis that stress-induced alterations of the joint surface include
not only varying degrees of subchondral lamellar mineralization, but
also histological changes of the subarticular cancellous bone.
Methods: To examine the structure of the subarticular cancellous
bone, ten formalin-fixed talar trochleae were analyzed using micro CT.
Sixteen measurement zones were defined and then evaluated in five
layers each of 1 mm thickness, enabling assessment of the cancellous
architecture extending 5 mm below the trochlear surface using
numerical and structural parameters.
Results: Like with mineralization patterns in the subchondral lamella,
large variation was observed regarding bone volume as well as
trabecular quantity, thickness, and spacing, depending on localization.
In addition, like previous reports examining mineralization of the
subchondral lamella, two distinct groups could be identified as
“bicentric” or “monocentric”.
Conclusion: These results show that structural tissue adaptation due
to loading history is also evident within the subarticular cancellous
bone.
FM6
The Role of the Deltoid Muscle in Basic and Pitching
Shoulder Motions using a Cadaveric Model
Claudio Rosso1 , Andreas Marc Müller1 , Andrea Cereatti2 , Arun J.
Ramappa3 , Ugo Della Croce2 , Victor Valderrabano4 , Ara Nazarian4 1 2 University Hospital Basel and University of Basel; Department of
Biomedical Sciences, University of Sassari Medical School, Sassari,
Italy; 3Department of Orthopaedic Surgery, Beth Israel Deaconess
Medical Center, Harvard Medical School, Boston, MA, USA; 4Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical
Center and Harvard Medical School, Boston, MA, USA
Purpose: To study the influence of the deltoid muscle on
glenohumeral translations in all three degrees of freedom in a
cadaveric setup with an intact torso.
Methods: In a previously published, validated testing system, both
shoulders of three fresh-frozen human torsos were tested in an intact
specimen and after complete removal of the deltoid in three
consecutive trials using five high-speed cameras by means of
bone-embedded markers. Abduction (ABD) and abbreviated throwing
motion (ATM) trajectories were tested. For statistical analysis, in
addition to the absolute trajectories, the area under the curve (AUC)
was calculated.
Results: When looking at the AUC the only significant difference
(p = .003) can be found in the Z-axis (medio-lateral translation) at
30–60° of abduction with values of 0.9 ± 0.4 mm. No other significant
different trajectories between the intact specimen and after deltoid
removal could be found.
Conclusions: Our finding support studies showing that deltoid
removal does not to cause a meaningful change in ABD and ATM
trajectories supporting the fact that the bulk effect might play only a
minor role in passive glenohumeral stabilization. These findings might
help researchers in planning kinematic and dynamic studies for open
surgery at the glenohumeral joint.
FM7
Physiological Achilles Tendon Length and its
Relation to Tibia Length
Claudio Rosso1 , Philipp Schütz2 , Caroline Polzer1 ,
Lukas Weisskopf3 , Ulrich Studler4 , Victor Valderrabano5 1 2 University Hospital Basel and University of Basel: Canton’s Hospital
Aarau; 3Rennbahn Clinic Muttenz, Switzerland; 4Department of
Radiology University Hospital Basel and University of Basel, Basel,
Switzerland; 5Orthopaedic Department, University Hospital Basel
University of Basel, Basel, Switzerland
Background: The optimal intraoperative Achilles Tendon Length
(ATL) adjustment is crucial for the physiological functioning of the
musculotendinous unit. To date, the resting ATL and its relation to
Tibia Length (TL) have never been defined in healthy subjects.
We thus performed metric measurements of the ATL and TL.
Methods: In this case series, 52 subjects were placed in a 3T-MRI
with the ankle in neutral position. Unilateral ATL was measured from
the calcaneal insertion to the beginning of the medial gastrocnemius
muscle. TL was measured from the intercondylar eminence to the
center of the ankle. Qualitative tendon parameters in T2-sequences
and human parameters were noted. Results were correlated with age,
gender, body height, weight, BMI, side of the AT and TL.
Results: The mean ATL was 180.6 ± 25.0 mm and the mean TL was
371.9 ± 25.4mm with an ATL/TL-ratio of 49 ± 5%. ATL correlated
significantly with body height (R2 = 38%, p