Frank Adam

Biomechanical Properties of Patellar and Hamstring Graft Tibial Fixation Techniques in Anterior Cruciate Ligament Reconstruction Experimental Study With Roentgen Stereometric Analysis

Background Reliable fixation of the soft hamstring grafts in ACL reconstruction has been reported as problematic. Hypothesis The biomechanical properties of patellar tendon (PT) grafts fixed with biodegradable screws (PTBS) are superior compared to quadrupled hamstring grafts fixed with BioScrew (HBS) or Suture-Disc fixation (HSD). Study Design Controlled laboratory study with roentgen stereometric analysis (RSA). Methods Ten porcine specimens were prepared for each group. In the PT group, the bone plugs were fixed with a 7 · 25 mm BioScrew. In the hamstring group, four-stranded tendon grafts were anchored within a tibial tunnel of 8 mm diameter either with a 7 · 25 mm BioScrew or eight polyester sutures knotted over a Suture-Disc. The grafts were loaded stepwise, and micromotion of the graft inside the tibial tunnel was measured with RSA. Results Hamstring grafts failed at lower loads (HBS: 536 N, HSD 445 N) than the PTBS grafts (658 N). Stiffness in the PTBS group was much greater compared to the hamstring groups (3500 N/mm versus HBS = 517 N/mm and HSD = 111 N/mm). Irreversible graft motion after graft loading with 200 N was measured at 0.03 mm (PTBS), 0.38mm (HBS), and 1.85mm (HSD). Elasticity for the HSD fixation was measured at 0.67 mm at 100 N and 1.32 mm at 200 N load. Conclusion Hamstring graft fixation with BioScrew and Suture-Disc displayed less stiffness and early graft motion compared to PTBS fixation. Screw fixation of tendon grafts is superior to Suture-Disc fixation with linkage material since it offers greater stiffness and less graft motion inside the tibial tunnel. Clinical Relevance Our results revealed graft motion for hamstring fixation with screw or linkage material at loads that occur during rehabilitation. This, in turn, may lead to graft laxity.

Extracorporeal shock wave therapy (ESWT) in patients with chronic proximal plantar fasciitis: a 2-year follow-up.

The aim of this study was to compare the effect of extracorporeal shock wave therapy (ESWT) in patients with chronically painful proximal plantar fasciitis with a further conventional conservative treatment. Forty-seven patients (49 feet) with a previously unsuccessful nonsurgical treatment of at least 6 months were randomized to two groups. Heel cups had to be worn throughout the study. Group 1 (25 heels) was treated immediately with three sessions of ESWT (3000 shock waves/session of 0.2 mJ/mm 2 ) at weekly intervals. The patients of group 2 (24 heels) continued nonsurgical treatment (iontophoresis with diclofenac and an oral nonsteroidal anti-inflammatory drug) for 12 weeks. After this period they were treated using the protocol of group 1. No significant difference of pain and walking time after further nonsurgical treatment (3 months) was seen in group 2. At 12 weeks after ESWT, the pain estimation on the visual analogue scale (VAS) for activities of daily living diminished significantly by 62.9% in group 1 and by 63.0% in group 2. The comfortable walking time had increased significantly in both groups. Two years after ESWT, pain during activities of daily living decreased by 94% in group 1 and by 90% in group 2 on the VAS and the comfortable walking time had increased significantly in both groups.

Femoral anatomy, computed tomography and computer-aided design of prosthetic implants

Abstract. Precise digital data of the internal femoral anatomy are necessary to develop new prosthetic implants with computer-aided design (CAD) techniques. Thirty human cadaveric femurs of central European origin were analysed by high precision computed tomography (CT) using thin slice and high resolution imaging. The CT data were image processed with thresholding to obtain a reconstruction of the cortical bone geometry. The CT threshold for cortical bone was optimized by comparison with saw cuts of macerated femurs. For each specimen a three-dimensional (3D) model of the cortical femur was calculated by the CAD system based on the processed CT data. Virtual 3D models of the 30 femurs were used to adjust a hypothetical stem to the proximal femur anatomy by repeated virtual implantations. The CAD system allowed for evaluation of anatomical parameters after hip reconstruction, amount of bone removal, and cortical bone contact. The fit and fill of the stem could be tested before clinical application and implant-related problems could be corrected.

Biomechanical properties of interference screw implantation in replacement of the anterior cruciate ligament with patellar and hamstring transplants. An experimental study using roentgen stereometry analysis (RSA)

ZusammenfassungMit Hilfe der Röntgenstereometrieanalyse (RSA) sollten bei Ersatzplastiken des vorderen Kreuzbandes (VKB) Relativbewegungen zwischen Transplantat und Bohrtunnel unter Last erfasst werden. Zielsetzung war die Bestimmung der Steifigkeit der Patellarsehneninterferenzverschraubung und der Vergleich mit der direkten Schraubenfixation von Hamstring-Transplantaten.Die Untersuchungen erfolgten an frischen Präparaten vom Schwein. In 10 Tibiae wurde ein 10×25-mm-Bone-patellar-tendon-bone-(BPTB-)Transplantat entweder mit einer 7×25-mm Titan- oder einer 7×25-mm-Polylactidschraube in einem 10-mm-Bohrloch fixiert. In der Vergleichsgruppe erfolgte die direkte Verschraubung eines 4fachen Hamstring-Transplantats mit einer 7×25-mm-Polylactidschraube in einem 8-mm-Bohrkanal. Knochenblock, Sehne, Schraube und Tibia wurden mit RSA-Markierungen versehen. Die Zugbelastung wurde stufenweise bis zum Versagen des Systems gesteigert. Mittels der RSA wurden auf jeder Belastungsstufe die Transplantatbewegungen im Bohrkanal bestimmt. Die RSA-Messgenauigkeit betrug 0,05 mm.Bei der direkten Verschraubung der 4fachen Hamstring-Sehne fand sich eine signifikant niedrigere maximale Haltekraft als bei der BPTB-Verschraubung (492±30 vs. 658±98 N). Die lineare Steifigkeit der Fixation war ebenfalls deutlich geringer (403±141 vs. 3500±1300 N/mm). Zwischen Polylactid- und Titanschraube fanden sich bei der BPTB-Verschraubung keine signifikanten Unterschiede. Bei den verschraubten Hamstring-Transplantaten zeigte sich bereits nach durchschnittlich 82±35 N Zuglast ein Nachgeben der Fixation (Elastizitätsgrenze). Die Elastizitätsgrenze der BPTB-Verschraubung lag mit durchschnittlich 428±135 N deutlich höher. Bei submaximaler Belastung mit 3/4 der maximalen Haltekraft fand sich beim Patellarsehnendrittel eine mittlere Migration in Zugrichtung von 0,36±0,25 vs. 2,58±1,08 mm beim Hamstring-Transplantat.Die direkte Verschraubung der 4fachen Hamstring-Sehne zeigte im Vergleich zur Interferenzverschraubung der Patellarsehne eine geringe lineare Steifigkeit und eine niedrigere Elastizitätsgrenze. Hierdurch kann es bereits bei physiologischer Last zu einem Rutschen des Sehnentransplantats in Zugrichtung kommen.AbstractThis experimental roentgen stereometric analysis (RSA) study was performed to measure micromotions between the graft and tunnel under submaximal load in anterior cruciate ligament (ACL) reconstruction. The aim was to evaluate the maximum load at failure, linear stiffness, and slippage of bone-patellar-tendon-bone (BPTB) grafts fixed with interference screws compared to quadrupled hamstring grafts fixed with interference screws.We used 15 porcine tibia specimens for the study. In the BPTB group, the 10×25-mm bone plugs were fixed in a tunnel with 10 mm in diameter using a 7×25-mm titanium interference screw (n=5) or a biodegradable screw (n=5). The five hamstring transplants were folded to a four-stranded graft and armed with a baseball stitch suture. The sutured side was fixed with a 7×25-mm biodegradable polylactide screw in an 8-mm tunnel. The tibial bones, tendon grafts, and interference screws were marked with tantalum beads. The grafts were mounted to a custom made load frame and loaded parallel to the axis under RSA control increasing the force in steps of 50 N. Micromotions between bone plug, screw, and tibia were measured with RSA.Accuracy of RSA for the in vitro study was evaluated as 0.05 mm. Hamstring grafts failed at significantly lower maximum loads (492±30 N) than BPTB grafts (658±98 N). Linear stiffness of the hamstring graft fixations was eight times lower compared to the BPTB grafts (403±141 N/mm vs 3500±1300 N/mm). There was no significant difference between the biodegradable and titanium screws in the BPTB group. Slippage of the graft started at 82±35 N load in the hamstring group and at 428±135 N in the BPTB group. Slippage of the graft at 75% of the maximum pull-out strength was measured as 0.36±0.25 mm in the BPTB and 2.58±1.08 mm in the hamstring group.The interference screw fixation of a quadrupled hamstring graft showed a lower linear stiffness and an earlier slippage compared to a patellar tendon bone plug. Slippage of the hamstring grafts at submaximal loads may result in fixation failure during rehabilitation.

Primary lumbosacral stability after open posterior and endoscopic anterior fusion with interbody implants: a roentgen stereophotogrammetric analysis.

Study Design. After posterior stabilization of the spondylolytic lumbosacral level, mobility of the fused vertebrae could be studied before and after an additional anterior endoscopic interbody fusion using roentgen stereophotogrammetric analysis. Objective. To determine the in vivo primary lumbosacral stability of additional anterior interbody fusion after transpedicular screw fixation. Summary of Background Data. In vitro studies indicate a significant decrease in segmental motion after pedicle screw fixation and additional anterior fusion. Roentgen stereophotogrammetric studies demonstrate the adequacy of transpedicular lumbar instrumentation in posterolateral fusions. There are no studies examining the effect of additional anterior interbody fusion after posterior instrumentation in vivo. Methods. In this study, 15 patients with low-grade spondylolisthesis at L5–S1 underwent a two-stage open posterior and endoscopic anterior lumbar fusion using carbon fiber (Brantigan I/F) cages. At surgery, tantalum markers were implanted into the fifth lumbar (L5) and the first sacral (S1) vertebra. All the patients were examined by roentgen stereophotogrammetric analysis after the first and second surgical procedures. Results. After implantation of the posterior pedicle system only, the mean intervertebral mobility determined by roentgen stereophotogrammetric analysis was 0.23 mm in the transverse (x), 0.54 mm in the vertical (y), and 1.2 mm in the sagittal (z) axes. After additional anterior endoscopic fusion with carbon cages, the remaining translation between the fused segment L5/S1 decreased to 0.17 mm in the x, 0.16 mm in the y, and 0.44 mm in the z axes. Conclusion. Anterior endoscopic lumbosacral fusion significantly increases the primary stability of the posterior fusion with a pedicle system in two axes of motion.

Lumbosacral stability of consolidated anteroposterior fusion after instrumentation removal determined by roentgen stereophotogrammetric analysis and direct surgical exploration

Study Design. The intervertebral stability of bony consolidated anteroposterior lumbosacral spondylodesis is evaluated by roentgen stereophotogrammetric analysis and direct surgical exploration before and after removal of the internal fixator. Objectives. To determine the remaining in vivo stability of spinal arthrodesis solely retained by a bony integrated carbon fiber cage. Summary of Background Data. Roentgen stereophotogrammetric analysis studies on posterolateral lumbar fusions demonstrate primary spinal stability after additional dorsal instrumentation, which is retained during bony fusion healing. Animal models show a persistent stabilizing effect of the fixator despite the presence of bony fusion. Although direct surgical inspection is the most reliable method to evaluate fused vertebrae, roentgen stereophotogrammetric analysis has also proven to be a highly accurate method to evaluate spinal stability. Methods. In 10 patients lumbosacral fusion was performed using carbon interbody implants and an internal fixator. Ten months after initial surgery (range 7–15 months) the internal fixation was removed to reduce local soft tissue impingement as soon as bony fusion was achieved. Fusion site exploration in the course of instrumentation removal was performed by applying distraction, compression, and torque to the grafted area under fluoroscopic control. Any motion indicated a pseudarthrosis. Lumbosacral stability was evaluated by serial roentgen stereophotogrammetric analysis after fusion and after instrumentation removal. Results. During instrumentation removal the mechanical stress test under fluoroscopic control did not indicate pseudarthrosis. After instrumentation removal, roentgen stereophotogrammetric analysis measurements revealed a nonsignificant increase in lumbosacral micromotions within the fused segment with 0.14, 0.31, and 0.44 mm in the transverse, vertical, and sagittal axes, respectively. Conclusions. The internal fixator could be removed without endangering the stability of the fusion. Direct surgical exploration confirmed the adequacy of roentgen stereophotogrammetric analysis as a reliable in vivo method to evaluate lumbosacral stability after anteroposterior fusion.

The internal calcar septum (femoral thigh spur) in computed tomography and conventional radiography.

Abstract Objective. The femoral ”thigh spur”, a cortical septum in the region of the lesser trochanter of the human femur, was first described and named by the German anatomist Merkel in 1874, but it was never examined in detail. To evaluate the frequency and the shape of this structure, a combined anatomical and radiological study was performed using saw-cuts from specimens, high-resolution CT and conventional radiography. Design. Thirty human cadaveric femora of central European origin were analyzed by high-precision computed tomography (CT) using thin slices and high-resolution imaging. The CT data were image processed with thresholding to obtain a reconstruction of high-density bone formations and for three-dimensional imaging. Additionally three macerated femur specimens were cut exactly corresponding to the CT slices. The computed images were validated with the anatomical saw-cuts. Results. A dense trabecular ridge protruding endosteally from the posteromedial cortex was found in all femora. This cortical septum reaching from the femoral neck to the distal part of the lesser trochanter separated the femoral cavity from the cancellous bone inside the lesser trochanter. On conventional radiography the femoral thigh spur could be visualized best in the frog-lateral view of the hip. Conclusion. The internal calcar septum is a constant cortical structure. It should be recognized when radiographs or CT images of the proximal femur are interpreted. It could be of importance for metaphyseal fitting of an endoprosthetic stem.

Blood loss in anterior cruciate ligament (ACL) reconstruction with and without intercondylar notchplasty: does it affect the clinical outcome?

Abstract Blood loss is associated with any surgical procedure and should be reduced wherever possible. It was our impression that notchplasty adds to the amount of postoperative bleeding after anterior cruciate ligament (ACL) reconstruction. With posterior placement of the tibial tunnel, notchplasty is optional in many cases. This study aimed to quantify blood loss with and without notchplasty after arthroscopically assisted ACL reconstruction using bone-patellar tendon-bone autografts. We performed a prospective clinical study of 58 patients, who had undergone arthroscopically assisted autogenous patellar tendon ACL reconstruction. In group I, a notchplasty was necessary according to the local anatomical criteria (intraoperative impingement test). In group II, ACL replacement could be performed without notchplasty. Single and total day drainage volume, serum and suction drain hemoglobin (Hb) and hematocrit (Hct) levels were monitored. One year after surgery, the patients were reviewed to assess the outcome according to the IKDC and Lysholm scores and the KT-1000 arthrometer. The total drainage volume was 448 ml (range 150–550 ml) in group I and 299 ml (range 50–420 ml) in group II (p < 0.001). The serum hematocrit (Hct) decrease was 9.7% in group I and 7.4% in group II (p < 0.001). At 12 months after surgery, the IKDC and Lysholm score evaluations and the KT-1000 arthrometer measurements revealed no clinical differences between the notchplasty and non-notchplasty groups. Despite a 30% increase in blood loss, notchplasty has been shown to be a useful procedure to prevent graft impingement without negative side-effects.