Interindividual reproducibility in perioperative rotational alignment of femoral components in knee prosthetic surgery using the transepicondylar axis

Femoral component malalignment is one of the main causes of persisting anterior knee pain after knee replacement. This study examined interindividual reproducibility in perioperative definition of the transepicondylar axis (TEA) as a reference for measuring the rotational alignment of the femoral component. Eight surgeons experienced in knee prosthetic surgery marked on Thiel-embalmed cadaver specimens the reference points that they would normally use to define the TEA during knee replacement. These were digitized by a video system, and all the spots defined by the surgeon were translated into a reference picture, allowing a digital analysis of the distances between all the spots marked. The maximal distance between the spots that the participants had marked as relevant for the TEA was 13.8 mm at the lateral and 22.3 mm at the medial epicondyle. Projecting all spots marked into one picture resulted in an area of 116 mm2 on the lateral and 102 mm2 on the medial epicondyle. The median range of the fault between two different participants was 6.4 mm on the lateral side (range 13.2 mm) and 9.7 mm on the medial (range 21.6 mm). Because the rotational alignment of the femoral component is extremely relevant for successful implantation of total knee prosthesis, the interindividual discrepancy in defining the TEA as reference is rather high. As this reference line is commonly used, the perioperative variance and the resulting rotational discrepancy of the femoral component must be considered.

[Basic principles and surgical technique of tibio-fibula-plasty in cartilage-bone transplantation]

BACKGROUND

Within the last few years autologous cartilage-bone-grafting is becoming an established standardized procedure in joint surgery. One significant disadvantage of this technique is the harvesting of the bone plugs from the weight-bearing area of the knee joint.

PURPOSE

The tibiofibular articulation is located close to the knee joint that is operated on. This articulation is covered with cartilage. The purpose of this study was to evaluate the question, whether this joint is suitable as a donor site for bone-cartilage transplants.

MATERIAL AND METHODS

Favourable approaches and committing of anatomical landmarks were investigated on 44 fixed tibiofibular joints. In knee extension, the shortest distance between the joint cleft and common fibular nerve was measured. The cartilage thickness and histology of both the fibular and tibial joint surface were documented. The developed surgical approach was evaluated in patients.

RESULTS

Histological and immunohistochemical examination showed hyaline cartilage and type II collagen. The average cartilage thickness was 1.9 +/- 0.29 mm (minimum: 1.5 mm; maximum: 2.6 mm). The peroneal nerve showed an average distance to the tibiofibular joint of 24 mm (minimum: 12 mm; maximum: 30 mm). Different surgical procedures are possible and clinical relevant.

CLINICAL RELEVANCE

The tibiofibular joint contains cartilage, which may be a reasonable donor site even for the elderly patient. Harvesting the graft from this area may avoid iatrogenic damaging of intraarticular weight bearing cartilage of the knee joint.

Rare but serious complications of acupuncture: traumatic lesions

Acupuncture has a reputation among the public of being safe. Although recently performed prospective studies on the frequency of adverse effects of acupuncture found no severe complication, since 1965 many case reports of serious or even life-threatening incidents caused by acupuncture have appeared in the scientific literature. The most frequently reported complications are pneumothorax and lesions of the spinal cord. Severe injuries of peripheral nerves and blood vessels due to acupuncture seem to be very rare. Although case reports do not produce reliable data on the frequency of adverse events. information on sources of application errors can be extracted to increase the quality of acupuncture in education and therapy. All traumatic injuries described in this article could be avoided if practitioners had better anatomical knowledge, applied existing anatomical knowledge better, or both.

Is there an option for harvesting autologous osteochondral grafts without damaging weight-bearing areas in the knee joint?

Within the past few years autologous osteochondral transplantation has become an established standardized procedure in joint surgery. One significant disadvantage of this technique is the harvesting of the osteochondral grafts from the weight-bearing area of the knee joint. The tibiofibular articulation is located close to the knee joint that is operated on. This articulation is covered with cartilage. The purpose of this study was to evaluate whether this joint is suitable as a donor site for osteochondral grafts. Ten human knee specimens were freed of all soft tissues around the proximal calf. The age of the specimens ranged between 58 and 79 years. Next the tibiofibular articulation was identified, and both the ligaments and the capsule were removed. After opening the joint the tibial- and fibular-sided joint surfaces were inspected and measured. In all specimens the articular surfaces showed good cartilage coverage. In only a single joint did the cartilage macroscopically show degeneration. In all other joints the cartilage surface was in surprisingly good condition, especially considering the age of the specimens. The average diameter of the cartilage surface on the tibial side was 1.7 +/- 0.26 x 1.9 +/- 0.22 cm and on the fibular side 1.6 +/- 0.31 x 1.8 +/- 0.32 cm. This results in an area of cartilage for transplantation of 3.23 cm2 at the tibia and of 2.88 cm2 at the fibula. The total area for cartilage transplantation is 6.11 cm2. The tibiofibular joint contains cartilage, which may be a reasonable donor site even for the elderly patient. Harvesting the graft from this area may avoid iatrogenic damaging of intra-articular weight-bearing cartilage of the knee joint.

Vitamin E reduces platelet adhesion to human endothelial cells in vitro

Although it has been reported that vitamin E (alpha-tocopherol) can reduce platelet adhesiveness and aggregation in vivo, the mechanism is still unknown. Therefore, the aim of the present study was to determine whether incubations of platelet-rich plasma (PRP) with vitamin E influence platelet adhesion to cultured endothelial cells. To exclude blood plasma involvement, also washed platelets were pretreated with alpha-tocopherol. Vitamin E (0.5-1.0 mM) was added to PRP or washed platelets. Endothelial cells in monolayer were incubated with thrombin-activated platelets (1 or 2 U/ml). After 1 hr of incubation, non-adhered platelets were removed and counted. Treating of PRP with alpha-tocopherol inhibited platelet adhesion to endothelial cell monolayer. This effect was dose dependent on concentrations of alpha-tocopherol and thrombin. In our experiments PRP was treated with alpha-tocopherol and endothelial cell monolayer was used as test surface. These findings agree with previous observations on the adhesivity of platelets to synthetic surfaces after dietary vitamin E in healthy volunteers. When washed platelets were incubated with alpha-tocopherol, no significant reduction of adhesion was detectable. As preincubation of washed platelets with alpha-tocopherol does not inhibit platelet adhesion, it may be supposed that the effect of vitamin E does not occur in a directly cellular mechanism. The data suggest that alpha-tocopherol may reduce platelet adhesiveness probably after incorporation by plasma lipoproteins.

Which stabilization technique corrects anatomy best in patients with AC-separation? An experimental study

In ten human cadaveric shoulder specimens four different parameters were documented prior to, and after, dissecting all passive stabilizers. These included the vertical, horizontal and mediolateral acromioclavicular distance, as well as the clavicular rotation. In addition, the same parameters were documented after acromioclavicular (AC) reconstruction using eight different techniques. The results showed a good reconstruction of the vertical ac-distance. Most of the techniques, especially the coracoid-sling procedure, led to a significant anterior displacement of the clavicle in relation to the scapula. To a lesser degree, most of the conventional procedures also resulted in a lateralization of the acromion and/or clavicular rotation. A bone anchor system for distal fixation in the base of the coracoid process and a medialized hole in the clavicle restored anatomy best. This new technique therefore is recommended for anatomical AC-reconstruction.

Computer assisted implantation of the femoral stem in THA - an experimental study

Fourteen femoral stems were implanted either manually by an experienced surgeon or by a robot in fresh human cadaveric femora. The neck-shaft angle, the anteversion, the length of the femoral neck and the gap between stem and bone was measured in each specimen. Implantation by robot showed higher precision in reconstructing the true anatomic situation as well as providing a better press fit.

[Increasing the quality of preoperative planning and intraoperative application of computer-assisted systems and surgical robots--an experimental study]

14 human femurs were scanned by CAT and 3D reconstructed. In every specimen digital documentation of CCD and antetorsion (AT) angle was performed. With a special software package (Orthodoc) virtual preoperative planning for implantation of a cementless total hip alloplasty was undertaken. The specimens were randomised into two groups, one of which had manual and the other one robot implantation of the femoral component. After implantation all specimens were evaluated again by CAT and CCT and AT angle were documented again. The preoperative CCD angle was 126.7 degrees (SD = 4.0) in the manual group and 127.8 degrees (SD = 4.3) in the robodoc group. Postoperatively the angle averaged 131.9 degrees (SD = 0.8) in the manual group and 133.2 degrees (SD = 1.9) in the robodoc group. Significant differences were found for the AT angle in both groups. The preoperative AT angle in the manual group was 31.3 degrees (SD = 8.8), decreasing to 20.5 degrees (SD = 9.5) after implantation. In the robodoc group this angle was 30.9 degrees (SD = 8.0) before and 31.3 degrees (SD = 8.7) after implantation. The difference between pre- and postoperative AT angle averaged 10.8 degrees (SD = 6.4) in the manual group and only 0.4 degree (SD = 0.9) in the robodoc-group.

CONCLUSIONS

With the technique used, preoperative planning in hip alloarthroplasty is much more accurate than with the conventional technique with plain X-ray. The virtual preoperative planning can be transferred to the intraoperative setting with high precision. These factors may lead to an increase in outcome quality.

[Percutaneous bipolar discectomy. Technical principles and initial results with an in vitro model]

In the present study, the effect of bipolar radio-frequency thermocoagulation of intervertebral discs was evaluated in an in vitro model. In fresh human cadaveric thoracic and lumbar motion segments, we applied radio-frequency energy to the intervertebral disc via a variety of different bipolar HF electrodes, while simultaneously recording the temperature of the dorsal longitudinal ligament. All the segments were weighed in a standardised manner prior to and after the procedure. It was found that a combination of coagulation and vaporisation was most suitable for working on the disc. Applying energy for 300 secs resulted in an average weight loss ranging, electrode-dependently, from 0.3 to 0.7 grams, the mean temperature increase in the longitudinal ligament was 0.1 degree C per min.

CLINICAL RELEVANCE

Our experimental data suggest that PBD may be used for the same indications as the laser in the treatment of disc disease.

[Clinical anatomy in surgical education and graduate education]

On the basis of the experience that knowledge of anatomy is not as sound in clinical education as it should be and with a view to the new licensing regulations for physicians, at the Westfälische Wilhelms-Universität Münster, Germany, we established an interdisciplinary anatomical education. Clinical practitioners from 14 different specialties together with anatomists give lessons in applied anatomy accompanying the dissection course, and clinical experienced anatomists guide senior medical students in parallel to the practical courses to refresh their anatomical knowledge. Conjointly clinical practitioners and anatomists initiate, organize and establish meetings in postgraduate surgical education and experimental surgery. All seminars are evaluated and have a very good compliance.