Drill Channels Research Articles

СОКОПРОДУКТИВНОСТЬ КЛЕНА ВЫСОКОГОРНОГО

In the North Caucasus are presented data on the intensity of sap production and sap productivity of the Trautvetter maple. Experimental tapping was carried out in an old-growth maple forest in the forest fund of North Ossetia-Alania, the Koban tract. Maple tapping was carried out by laying drill channels with a diameter of 10 mm and a depth of no more than 30 mm. From 1 to 4 channels were laid on one trunk. A polyvinyl chloride tube with an outer diameter of 10 mm was used as a sap line. Plastic containers with a volume of 5 and 10 liters served as juice collectors. The volume of secreted juice was determined with an accuracy of 10 ml. It has been established that the intensity and duration of juice secretion depends on the weather conditions at the beginning of the growing season. The sap productivity of the Trautfetter maple also depends on the size of the tree and its condition. A direct and strong dependence of the intensity of juice secretion on the diameter of the trunk has been proven - the larger the diameter, the more juice. At the same time, there are cases when the intensity of sap production by trees with a small trunk diameter is higher than that of trees with a trunk diameter of about 1 m. It is noted that the presence of heart rot and hollowness of the trunk affects both the intensity of sap production and sap productivity. An interesting feature was revealed in individual Trautfetter maple trees: when 2-4 sapling canals are laid on one trunk, sap flow from one, or less often from two canals at once, quickly stops. The period of rapid decrease in juice secretion takes from 30 minutes to several hours. A characteristic phenomenon for alpine maple is the growth of trees in nests, when from 2 to 10-12 trunks develop from a single root system. It is indicated that the intensity of sap production does not depend on the number of trees in the “nest”, and the overall sap productivity of the “nest” is higher than that of individual trees.

Comparative Accuracy of Intraoral and Extraoral Digital Workflows for Short Span Implant Supported Fixed Partial Denture Fabrication: An In Vitro Study.

BACKGROUND The advent of digital impressions using computer-aided design and manufacturing technology (CAD/CAM) has simplified and improved the fabrication of implant prostheses in dentistry. The conventional impression has several drawbacks, including tray selection, material type, impression technique, impression disinfection, and cast model storage. The inaccuracies caused by distortion and contraction of impression material can be minimized with digital impressions. This study aimed to compare digital dental impressions of 10 working casts made using the Pindex laser removable die system to fabricate parallel drill channels vs 10 working casts made using the Di-Lok plastic tray removable die system. MATERIAL AND METHODS An implant master die with 2 dental implant analogs was fabricated. Ten working casts using the Pindex laser removable die system with parallel drill channels and 10 working casts using the Di-Lok plastic tray removable die system were fabricated. The working casts were scanned using an extra-oral laboratory scanner and the implant master model was scanned with an intra-oral scanner. RESULTS The properties of the casts made using the 2 systems were evaluated and analyzed with ANOVA and post hoc Tukey test. The mean horizontal linear distances between A1B1 (P<0.021), A2B2 (P<0.018), C1D1 (P<0.026), C2D2 (P<0.03), B1C1 (P<0.01), and mean vertical distances between B1A2 (P<0.015), C1D2 (P<0.001), B1B2 (P<0.028), and C1C2 (P<0.001) were significantly different between the Pindex system and Di-Lok tray system as compared to intra-oral scans. CONCLUSIONS Complete digital workflow with intra-oral scans were more than the partial digital workflow with extra-oral scans for the Pindex system and Di-Lok tray systems.

3D C-arm navigated acromioclavicular joint stabilization

IntroductionSurgical treatment options for acromioclavicular joint separations are varied. Frequently, suspension devices (SD) are inserted for stabilization under arthroscopic view. This study investigates the feasibility and accuracy of three-dimensional (3D) digital-volume-tomography (DVT) C-arm navigated implantation with regard to the general trend toward increasingly minimally invasive procedures.Materials and methodsThe implantation of a TightRope® suture button system (SD) via a navigated vertical drill channel through the clavicle and coracoid was investigated in 10 synthetic shoulder models with a mobile isocentric C-arm image intensifier setup in the usual parasagittal position. Thereby, in addition the placement of an additive horizontal suture cerclage via a navigated drill channel through the acromion was assessed.ResultsAll vertical drill channels in the Coracoclavicular (CC) direction could be placed in a line centrally through the clavicle and the coracoid base. The horizontal drill channels in the Acromioclavicular (AC) direction ran strictly in the acromion, without affecting the AC joint or lateral clavicle. All SD could be well inserted and anchored. After tensioning and knotting of the system, the application of the horizontal AC cerclage was easily possible. The image quality was good and all relevant structures could be assessed well.ConclusionIntraoperative 3D DVT imaging of the shoulder joint using a mobile isocentric C-arm in the usual parasagittal position to the patient is possible. Likewise, DVT navigated SD implantation at the AC joint in CC and AC direction on a synthetic shoulder model. By combining both methods, the application in vivo could be possible. Further clinical studies on feasibility and comparison with established methods should be performed.

Limb-sparing resection of axillary soft tissue sarcomas

For patients with soft tissue sarcoma, surgical resection is akey element of curative therapy. Surgery is performed as awide resection with microscopically negative margins (R0resection) and as limb-sparing procedure whenever possible to preserve maximum function. Soft tissue sarcoma, metastases. Extensive disease with major neurovascular involvement, placement of biopsy tract necessitates extensive resection, palliative care. Extended deltopectoral approach. Release of pectoralis major and minor tendons. Vascular and neurologic exploration, identification of the axillary vessels and brachial plexus, placing of loops around major structures. Mobilization of these structures to achieve adequate exposure. Clipping of vessels entering the tumor. Tumor resection, suture marking for histological analysis. Soft tissue reconstruction by transosseous reinsertion of the pectoralis minor to the coracoid process. Drill channel placement, transosseous refixation of the pectoralis major to the humerus. Shoulder abduction brace for 6weeks, passive mobilization for 6-12weeks followed by active mobilization. Compression sleeve. Oncological follow-up. Between 2017 and 2022, wide resection was performed in 6consecutive cases including 4 primary soft tissue sarcomas and 2metastases. Primary R0 resection was achieved in 100%. Mean follow-up was 22.5months (3-60months). There were no local recurrences. Mean active shoulder abduction was 135.0 ± 41.4° (90-180°). Neurological deficits were not observed. Mean subjective shoulder function was 80.0 ± 21.0% (50-100%). The mean Musculoskeletal Tumor Society (MSTS) score was 89.5% (32-100%), indicating good functional outcome in the study cohort.

Implant-dependent behavior of tunnel widening and clavicular button migration after arthroscopic-assisted treatment of acromioclavicular joint instabilities.

Despite ongoing discussions for the previous few decades, there is still no consensus regarding the optimal surgical technique for acromioclavicular joint instabilities. The purpose of this study was to determine the impact of various implant materials following arthroscopically assisted stabilization of acromioclavicular joint instabilities on tunnel widening and implant migration. We hypothesized an implant-dependent behavior for tunnel widening and implant migration with differences when comparing acute and chronic acromioclavicular joint instabilities. This study compared 105 patients with acromioclavicular joint instabilities that were managed operatively with coracoclavicular double button constructs. Two of the groups containing acute cases were treated with either a double button construct with a wire (TR) or a tape (D) as a central pillar. The two groups with chronic cases were either treated with a wire (T+) or tape D+ as a central pillar and additional hamstring tendon augmentation (+). One central transclavicular-transcoracoidal drill channel was made in the acute cases, while additional medial and lateral drill channels to augment the central pillar with the hamstring tendon were made. The central drill channel in all cases and the medial/lateral drill channels in chronic cases were subsequently radiologically analyzed immediately postoperatively and at follow-up. Following this, additional radiological analysis of the implant migration of the clavicular button took place. All groups showed significant tunnel widening of the central drill channel at follow-up (p ≤ 0.001). The TR+ technique demonstrated significant widening in both the medial (p ≤ 0.001) and lateral (p ≤ 0.001) drill channels. The D and D+ group displayed significant higher rates of clavicular button migration to a cortical and intraosseous level (p ≤ 0.002). Tunnel widening and implant migration following arthroscopically assisted management of acromioclavicular joint instabilities are dependent on the chosen implant. The stable tape showed a significantly increased degree of tunnel widening with respect to the central drill channel in comparison with the wire. In contrast, a higher degree of load capacity of the tape ultimately favors a protected intraosseous graft healing for chronic cases, which leads to less tunnel widening of the medial and lateral drill channel. Finally, the D/D+ implant groups showed higher rates of implant migration due to lower contact surface area of the implant at the upper clavicular cortex.

“Flexible nature of fixation” in syndesmotic stabilization of the inferior tibiofibular joint affects the radiological reduction outcome

PurposeFibular mobility after suture button stabilization (SBS) of inferior tibiofibular joint (syndesmosis) injuries has been described. This effect is called the “flexible nature of fixation (FNF).” In this study, we aimed to quantify FNF in syndesmotic stabilization.MethodsPostoperative bilateral computed tomography (CT) of ankle fractures with syndesmosis stabilization by SBS or syndesmotic screw (SYS) was retrospectively analyzed. The transverse offset (TO) and vertical offset (VO) were defined by evaluating the drill channels. The reduction outcome was evaluated by the side-to-side difference between the clear space and the anterior tibiofibular distance (antTFD). The calculated anterior tibiofibular distance (cal-antTFD) was calculated by subtracting the TO from the validated antTFD. Subsequently, a reevaluation of the reduction outcomes after SYS or SBS stabilization was performed using cal-antTFD.ResultsSixty patients (44 with SBS and 16 with SYS stabilization) were analyzed. The intra-rater and inter-rater reliabilities for TO and VO were excellent (α > 0.92). SYS stabilization showed lower mean TO (− 0.02 mm; SD 0.14) and VO (0.11 mm; SD, 0.29 mm) than SBS stabilization (TO 1.16 mm, SD 1.4 mm; VO 0.2 mm, SD 0.8 mm; p = 0.001). The rate of malreduction according to cal-antTFD was higher than that of antFTD (p = 0.033).ConclusionThe presented method, which evaluates the position of the tibial to the fibular drill channel, allowed the quantification of the “FNF.” The often described difference in the dynamic stabilization of SBS compared to the rigid stabilization by SYS could be objectified. Considering cal-antTFD illustrates that FNF potentially reduces the rate of malreduction in SBS stabilization.

Effect of different dental implant drilling template designs on heat generation during osteotomy - an in vitro study.

This in vitro study examined the effect of different implant drilling template designs on heat generation during osteotomy and on cooling fluid distribution. Five different template designs were investigated in a standardized setup against a control group and a negative control group: Occlusal-splint-design (OSD), OSD-covering, OSD-lateral opening, Bar design, and Orientation template. Pilot and one consecutive drill were run at 800rpm with external irrigation and 2-kg load. Thermocouples recorded temperature changes at depths of 3, 6, and 9mm in a bovine rib model. In the second experimental setup, the drill channel of one rib sample was perforated, and the irrigation volume passing through the drill channel was collected separately over time. Following mean temperature rises occurred [in °C]: control, 4.9; negative control, 12; OSD, 5.6; OSD-covering, 4.7; OSD-lateral opening, 3.8; Bar design, 5.1; and Orientation template, 4.9. The highest temperature increases were found at a drilling depth of 6mm (p<.006). The 2.2-mm drill resulted in a significantly higher temperature rise than the 2.8-mm drill (p<.001). The mean volume (ml/min) of irrigation through the drill channel was Control group-flow, 28.5; OSD, 4.1; OSD-covering, 2; OSD-lateral opening; 5.8; bar design, 4; and Orientation template, 24.1. Within the limitations, it was shown that fully guided drilling templates reduce the amount of cooling liquid at the point of osteotomy. The template designhad an influence on the effective volume of the cooling liquid. However, this did not seem to increase the intraosseous temperature significantly.

The impact of artisanal gold mining, ore processing and mineralization on water quality in Marmato, Colombia

Marmato, Colombia, has been an important centre of gold mining since before the first Spanish colonizers arrived in 1536. The Marmato deposit is hosted in a dacite and andesite porphyry stock as sheeted sulphide-rich veinlet systems. The district is currently experiencing a surge in both major mining projects and artisanal mining, driven by sustained high gold prices. Ore from small-scale and artisanal gold mining is processed in numerous small mills (entables) around Marmato, which impact surface water quality through the discharge of milled waste rock slurry, highly alkaline cyanide-treated effluent, and high dissolved metal loads. To investigate the impact of artisanal mining and ore processing, water samples were collected in January 2012 from streams around Marmato. The average dissolved metal concentrations in impacted streams were Zn, 78 mg L−1; Pb, 0.43 mg L−1; Cu, 403 µg L−1 Cd, 255 µg L−1; As, 235 µg L−1; Ni, 67 µg L−1; Co, 55 µg L−1; Sb, 7 µg L−1; and Hg, 42 ng L−1, exceeding World Health Organization drinking water guidelines. In addition, arsenic speciation was conducted in-situ and indicated that 91–95% of inorganic arsenic species is in the form of As(V). Spatial analysis of the data suggests that entables processing ore for artisanal miners are the main contributor to water pollution, with high sediment loads, alkalinity and elevated concentrations of dissolved arsenic, cadmium, mercury and lead, caused by the processing of gold-bearing sulphides in the entables. Geochemical data from surface water were compared to a comprehensive data set of whole rock analyses from drill core and channel samples from the deposit, indicating that the deposit is significantly enriched in gold, silver, lead, zinc, arsenic, antimony, and cadmium compared to crustal averages, which is reflected in the surface water geochemistry. However, elevated mercury levels in surface water cannot be explained by enrichment of mercury in the deposit and strongly suggest that mercury is being added to concentrates during ore processing to amalgamate fine gold.

Arthroscopic anatomy of the posterolateral corner of the knee: anatomic relations and arthroscopic approaches

IntroductionAlthough open-surgical techniques for the reconstruction of the posterolateral corner (PLC) are well established, the use of arthroscopic procedures has recently increased. When compared with open surgical preparation, arthroscopic orientation in the PLC is challenging and anatomic relations may not be familiar. Nevertheless, a profound knowledge of anatomic key structures and possible structures at risk as well as technical variations of arthroscopic approaches are mandatory to allow a precise and safe surgical intervention.Materials and methodsIn a cadaveric video demonstration, an anterolateral (AL), anteromedial (AM), posteromedial (PM) and posterolateral (PL) portal, as well as a transseptal approach (TSA) were developed. Key structures of the PLC were defined and sequentially exposed during posterolateral arthroscopy. Finally, anatomic relations of all key structures were demonstrated.ResultsAll key structures of the PLC can be visualized during arthroscopy. Thereby, careful portal placement is crucial in order to allow an effective exposure. Two alternatives of the TSA were described, depending on the region of interest. The peroneal nerve can be visualized dorsal to the biceps femoris tendon (BT), lateral to the soleus muscle (SM) and about 3 cm distal to the fibular styloid (FS). The distal attachment of the fibular collateral ligament (FCL) can be exposed on the lateral side of the fibular head (FH). The fibular attachment of the popliteofibular ligament (PFL) is exposed at the tip of the FS.ConclusionArthroscopy of the posterolateral recessus allows full visualization of all key structures of the posterolateral corner, which provides the basis for anatomic and safe drill channel placement in PLC reconstruction. A sufficient exposure of relevant anatomic landmarks and precise portal preparation reduce the risk of iatrogenic vascular and peroneal nerve injury.

Why do MPFL reconstructions fail today?

Aims and Objectives:The medial patellofemoral ligament (MPFL) is the most important passive stabilizer of the patella. In recurrent lateral patellar dislocations reconstruction of the MPFL with an autologous tendon transplant is a frequently performed surgical procedure that shows a low redislocation rate between 1%-7%. However, a complication rate of up to 26% and a reoperation rate of 4% has also been observed. The question, therefore, arises which parameter determines MPFL reconstruction failure. Thus, the purpose of this study was to identify reasons for MPFL reconstruction failure with regard to patients’ complaints leading to reoperation.Materials and Methods:Between July 2015 and May 2019 28 patients (M/F 9/19; mean age 27 ± 8 years) with postoperative complaints after MPFL reconstructive surgery had to undergo revision surgery. Preoperative failure analysis included clinical examination (ROM, ReDPAT, J-sign, and Patella-Glide Test) and radiological imaging with regard to anatomical risk factors of patellar instability and MPFL tunnel positioning. Anatomical predisposition was assessed according to Dejour’s classification of trochlear dysplasia, tibial tuberosity-trochlear groove distance, tibial tuberosity-posterior cruciate ligament distance, patellar height, varus/valgus malalignment and torsional profile.Results:Three major reasons for revision surgery were identified: (1) patellar redislocation, (2) limited range of motion (ROM), and (3) anterior knee pain (AKP). Sixteen of the 28 patients (57%) suffered from recurrent patellar dislocation. Severe trochlear dysplasia (type B/D according to Dejour) (44%), valgus deformity (19%), increased patellar height (19%), and misplaced femoral drill channels (31%) could be identified as risk factors for redislocation. An increased TT-TG (>20mm) or TT-PCL (>24mm) distance could not be observed in any patient in this group. Limited ROM with an average maximum flexion ability of about 92 ± 26° was observed in 10 of the 28 patients (36%), of which 9 patients additionally complained of AKP. Misplaced femoral drill channels (80%), severe trochlear dysplasia (type B/D according to Dejour) (20%) and postoperative decreased patellar height (20%) could be identified as risk factors for postoperative limited ROM. Other reasons for postoperative AKP were increased femoral antetorsion (n=1) and retropatellar cartilage damage (n=2) without any loss of ROM.Conclusion:Recurrent dislocation of the patella, limited ROM and AKP were identified as most common complications after MPFL reconstruction leading to revision surgery. Failures are mainly due to neglected bony risk factors of patellar instability (trochlear dysplasia, patella alta and valgus deformity) and to misplaced femoral drill channels. Appropriate patient selection and an accurate surgical technique appear mandatory for a good clinical outcome when patellar instability is treated solely with an MPFL reconstruction.

An All-Arthroscopic Technique for Complex Posterolateral Corner Reconstruction

Injuries to the posterolateral corner (PLC) often result in lateral, rotational, and dorsal instability, which need appropriate and differentiated treatment. Besides posterior cruciate ligament reconstruction for posterior instability, the technique according to LaPrade et al. efficiently stabilizes posterolateral rotational and lateral instability as described in Fanelli type B or C injuries. This technique has been exclusively used as an open procedure. In this article, we present an all-arthroscopic technique for the posterolateral stabilization procedure. To achieve this, 5 different arthroscopic portals are needed. The PLC is visualized by a trans-septal approach. Directly posterior to the popliteal tendon, arthroscopic preparation is started and the medial part of the fibular head is exposed. Two anatomic drill channels are placed in the lateral femoral condyle, with one tibial channel in the distal third of the sulcus popliteus and one channel in the fibular head. The popliteal tendon, popliteofibular ligament, and lateral collateral ligament are reconstructed with autologous hamstring tendons. The advantages of an all-arthroscopic anatomic PLC reconstruction are the protection of the soft tissues and the precise anatomic tunnel placement under direct visualization. The described procedure is a safe and anatomic method for posterolateral stabilization.

Methodical Approach for Determining the Length of Drill Channels in Osteosynthesis.

In order to fix a fracture in osteosynthesis, it is necessary to attach screws bicortically to the bone. The length of the screws must be selected correctly in 1-mm increments: otherwise, injury to the surrounding tissue structure or insufficient fixation will result. The drill channel length can only be determined preoperatively to a limited extent and with insufficient accuracy and is therefore determined intraoperatively with a mechanical caliper gauge. This length determination is error-prone, which often leads to a false screw selection and at the same time to considerable complications in the healing process. A novel approach based on a sensory drive train was pursued, with which all mechanical drilling parameters were recorded and evaluated in combination with a length measurement that allows for determining the drill channel length. In order to overcome the limitations of previous drill concepts, a precise length measurement of the drill channel was introduced. The amplitude of a stimulated linear oscillation of the drill was monitored for drilling channel length measurements in order to reliably detect the beginning of the drilling process. The method provides the information required for handheld drilling without the limitation of constant drilling parameters. With initial results from laboratory tests with pig bones, the measurement method for the drill channel length has been validated on a test bench of the drilling machine. With the laboratory tests, a measurement uncertainty of 0.3 mm was achieved, so screws with a 1-mm step width can be reliably selected.

Residual Endodontic Filling Material after Post Space Preparation: A Confocal Microscopic Study.

This laboratory study assessed removability of endodontic alkaline cements and resin sealers using coronal cross-sectional slices of roots with single canals. Materials were labelled with 0.1% (w/w) sodium fluorescein prior to mixing so that confocal microscopy could be used to quantify material remaining on the walls of post spaces, to assess cleanliness. Roots of extracted teeth were prepared using rotary NiTi instruments then obturated using lateral condensation with gutta percha and epoxy resin sealers (AH-Plus™ or Zirmix™), or were filled by injecting mineral trioxide aggregate (MTA) cement (GC Nex™ MTA or MTAmix™) or a hard-setting calcium hydroxide cement (Supercal™). Brown (#3) ParaPost™ drills were used at 600 rpm with a torque setting of 3 N cm−1 for 2 min to remove 5 mm of the root filling. Roots were embedded and coronal slices examined by confocal microscopy, with the perimeter of the drill channel divided into clean, unclean and non-accessible regions. The choice of material affects cleanliness, with MTA being the most difficult and calcium hydroxide cement the easiest to remove. With epoxy resin-based sealers, almost half of the accessible canal walls remained coated with remnants of sealer after post space preparation.

A Research on Seepage Detection Technology of Water Storage Dam in Secondary Disaster Prevention of Water Resources

Dam leakage is an important aspect of secondary disaster of water resources. The heat transfer theory is used for the quantitative analysis of the abstract linear heat source model, which determines the flow rate of water leakage. Based on the abstract model of dam seepage, we use the thermal fluid knowledge to analyze and solve the key parameters. Based on the measured data, the model quantitatively calculates the water velocity and radius of seepage channel. Compared with the measured flow velocity of drill channel, the two conclusions basically proves the accuracy and validity of the method.

Interpolation and Sampling Errors of the Ash and Sulphur Contents in Selected Polish Bituminous Coal Deposit (Upper Silesian Coal Basin – USCB) / Błędy Interpolacji I Opróbowania Zawartości Popiołu I Siarki W Wytypowanych Polskich Złożach Węgla Kamiennego (Górnośląskie Zagłębie Węglowe)

Abstract The basic sources of information on the parameters characterizing the quality of coal (i.e. its ash and sulphur contents) in the deposits of The Upper Silesian Coal Basin (Poland) are drill core sampling (the first stage of exploration) and channel sampling in mine workings (the second stage of exploration). Boreholes are irregularly spaced but provide relatively uniform coverage over an entire deposit area. Channel samples are taken regularly in mine workings, but only in the developed parts of the deposit. The present study considers selected seams of two mines. The methodology used is based on detailed geostatistical analysis, point kriging procedure and P. Gy’s theory of sampling. Its purpose is: • defining and comparing geostatistical models for variability of the ash and sulphur contents for data originating from boreholes and mine workings, • predicting by means of point kriging the values of the parameters and errors of interpolation using data from boreholes at grid points where underground mine workings were later channel-sampled, • assessing the accuracy of interpolation by comparison of predicted values of parameters with real values (found by channel sampling), • evaluating the variances of total secondary sampling error (error of preparation of assay samples) and analytical error introduced by assaying of sulphur and ash, • assessing the contribution of sampling and analytical errors (global estimation error) to the interpolation errors. The authors found that the interpolation errors for ash or sulphur content are very large, with mean relative values of 35%-60%, mainly caused by the considerable natural variability, a significant role of random component of variability, and heterogeneity of spatial distribution of these characteristics. The sampling and analytical errors play a negligible role. Their values are smaller than 11% of interpolation error values. Presenting estimates of the spatial distribution of ash and sulphur contents in coal seams by means of contour maps is unreasonable if they are based on drill core sampling.

Erratum to: Arthroscopic reconstruction of the popliteus complex: accuracy and reproducibility of a new surgical technique.

With combined PCL reconstruction and a minimal invasive (extra-anatomical) Larson's procedure, dorsal instability can be reduced by about 50-70 %. Better results are described by open and more anatomical procedures. In this study, a new, standardized, arthroscopic technique for anatomical popliteus tendon (PLT) reconstruction is evaluated.In 13 cadaver knees, an arthroscopic reconstruction of the PLT and the lateral collateral ligament was performed. Twelve defined landmarks were used for arthroscopic tunnel placement, and the distance of the tunnel locations to these specific landmarks was evaluated.The femoral drill channel was located with a high degree of accuracy and reproducibility in the centre of the femoral footprint of the PLT (on average 1.1 (±1.6) mm distal from the centre). On the tibial side, the drill channel was in the distal third of the sulcus popliteus in all cases. On average, the channel was placed exactly at the level of the tip of the fibula (±1.5 mm) and 0.6 (±1.7) mm medially from the medial edge of the fibula. The centre of the channel was 13.4 (±2.3) mm distal from the joint line.The presented arthroscopic technique for PLT reconstruction is standardized, reproducible and has a high accuracy for the placement of the tibial and femoral tunnel. The technique could be clinically relevant for future arthroscopic posterolateral corner reconstructions.III.

Dynamic in vitro analysis of tractile forces of the anterior cruciate ligament (ACL) transplant using patellar and semitendinosus muscle tendon: a cadaver study.

The presented biomechanical study focused on the in vitro analysis of tractile forces working on the anterior cruciate ligament (ACL) and the ACL transplants, respectively, using a semitendinosus and/or patellar tendon during a passive flexion-extension movement (150-0°). Overall, 15 fresh frozen human knee joint pairs were examined. At first during arthroscopy, the tibial insertion of the ACL was drilled using a special hollow drill. Thereby, a bone cylinder was exposed at which a dynamometer was attached to enable for direct registration of tractile forces on the ACL via the connection between ACL-dynamometer and computer. The ACL transplant was fixed at the femur using a so-called endo-button, whereas the dynamometer was attached to the tibial end of the ACL transplant. The dynamic part of the examination was performed using the knee kinemator device developed by Plitz and Wirth et al. using different preload. The curves of the tractile forces of the ACL were qualitatively homogeneous with only low force values in the middle flexion position, whereas during maximum flexion and extension the forces increased reaching a maximum in the 0° position. Also, in testing the ACL transplants a force decrease between 0 and 50° flexion was recognized with even greater forces resulting at the 150° position depending on the anterior position of the femoral drill channel for implanting the ACL transplant. The amount of pre-loading showed no influence on the form of the tractile force curve. However, by enhancing the preload to 70 N, the maximal force in the ACL transplant increased significantly. The tractile forces assessed within the ACL during passive flexion movements between 10 and 90° were not greater than the forces measured in the ACL transplants. Thus, the clinical consequence is that in the early postoperative phase passive mobilization might be performed in this motion range without putting the ACL transplant at risk for damage.

Equipment for the Study of Machinability by Drilling under Constant Force Feed

The problem of machinability evaluation by constant force feed drilling was addressed in this paper. One of the objectives of the research presented in this paper was the decrease of the influence exerted by the presence of chips in drill channels and achieving equipment able to correspond to such a requirement. The use of value analysis method allowed identifying a solution of device able to ensure simpler conditions for materialization of test corresponding to machinability evaluation by drilling under constant force feed. One analyzed various machining schemas for achieving a drilling process. Equipment for drilling under constant force feed was designed. Essentially, a vertical feed motion up down could be achieved by the device for clamping the test piece, while the drilling tool achieves the rotation motion. The feed motion is generated under the action of some weights. One also developed a preliminary experimental research for verifying the conditions of equipment operation.

Arthroscopic reconstruction of the popliteus complex: accuracy and reproducibility of a new surgical technique.

With combined PCL reconstruction and a minimal invasive (extra-anatomical) Larson's procedure, dorsal instability can be reduced by about 50-70%. Better results are described by open and more anatomical procedures. In this study, a new, standardized, arthroscopic technique for anatomical popliteus tendon (PLT) reconstruction is evaluated. In 13 cadaver knees, an arthroscopic reconstruction of the PLT and the lateral collateral ligament was performed. Twelve defined landmarks were used for arthroscopic tunnel placement, and the distance of the tunnel locations to these specific landmarks was evaluated. The femoral drill channel was located with a high degree of accuracy and reproducibility in the centre of the femoral footprint of the PLT (on average 1.1 (±1.6) mm distal from the centre). On the tibial side, the drill channel was in the distal third of the sulcus popliteus in all cases. On average, the channel was placed exactly at the level of the tip of the fibula (±1.5mm) and 0.6 (±1.7) mm medially from the medial edge of the fibula. The centre of the channel was 13.4 (±2.3) mm distal from the joint line. The presented arthroscopic technique for PLT reconstruction is standardized, reproducible and has a high accuracy for the placement of the tibial and femoral tunnel. The technique could be clinically relevant for future arthroscopic posterolateral corner reconstructions. III.

Revision of anterior cruciate ligament reconstruction with patellar tendon allograft and autograft: 2- and 5-year results

The most common failure reasons of an anterior cruciate ligament (ACL) graft are incorrect positioning of the drill channels and insufficient fixation. In many cases, one-stage revision with patellar tendon graft and the appropriate corrections are possible. For previous use of the ipsilateral patellar tendon third, an allograft seems favorable for reconstruction. So far, no study compared the results of revision surgery of autologous versus allogenous patellar tendon grafts for revision surgery of the ACL in a 5-year follow-up. A retrospective study was conducted to analyze the clinical outcome and stability results 2 years (19.2 ± 5.8 months) and 5 years (68.8 ± 6.8 months) after revision of ACL reconstruction using middle-third patellar tendon allografts and autografts. The allografts were cleansed by mechanical means only. There were 15 patients in the allograft group and 14 in the autograft group. Patients with isolated re-rupture of the ACL graft were included in the study. Clinical results were evaluated by International Knee Documentation Committee 2000 forms (IKDC), Lysholm score, Tegner activity score, and visual analog scale. Stability was evaluated by means of KT-1000 arthrometer, Lachman test, and pivot-shift test. Location of drill holes was evaluated radiologically. Gonarthritis was graded according to Kellgren and Lawrence on the basis of radiographs. There were no significant differences between the two groups in anterior translation, manual examination for stability, IKDC 2000 findings, Tegner activity score, or Lysholm score. Extension deficits were more frequent in the autograft group at the first follow-up (P = 0.010). Lateral gonarthritis and femoral tunnel widening were more common in the allograft group at the second follow-up (P = 0.049 and P = 0.023, respectively). Pain on walking downhill was significantly more frequent in the allograft group at the second follow-up (P = 0.027). The functional results with allografts that had not undergone irradiation or chemical sterilization were comparable to those with autografts in ACL revision surgery. Allografts represent a good alternative to autogenous patellar tendons in revision surgery.