Ligament stability of the metacarpophalangeal joint: a biomechanical study

Capsuloligamentous contributions to metacarpophalangeal joint stability were obtained from load-displacement tests on the joints of 15 human cadavers. The contribution of each ligament to joint stability was obtained by measuring the reduction of load that induced a given joint displacement after sequential ligamentous sectioning. Four modes of joint displacement were examined: distal distraction, dorsopalmar dislocation, abduction-adduction rotations, and supination-pronation rotations. This study demonstrated that both radial and ulnar collateral ligaments play primary roles in stabilizing the metacarpophalangeal joint in all four modes of joint displacement. The accessory collateral ligaments contribute primarily to abduction-adduction rotational stability, but contribute little to stabilizing dorsopalmar dislocation or axial (supination-pronation) rotations. The palmar plate prevents dorsal dislocation only at full extension. The dorsal capsule has a moderate contribution to stability in distraction and supination-pronation rotations.     

Distal tibial oblique osteotomy for reconstruction of ankle joint congruity and stability

Teramoto distal tibial oblique osteotomy (DTOO) is a joint-preserving surgery for ankle osteoarthritis (AOA). However, there are few articles on the radiological assessment of DTOO. The purpose of this study was to report the clinical outcomes and radiological evaluations of weight-bearing radiographs before and after DTOO.We retrospectively reviewed 52 patients who underwent DTOO between 2007 and 2018. We recorded the Tanaka–Takakura classification, fixation methods, Japanese Society for Surgery of the Foot Ankle/Hindfoot Scale (JSSF scale), and complications. The tibial articular surface angle (TAS), medial malleolar angle (MMA), tibial lateral surface angle (TLS), talar tilt angle (TTA), and tibiotalar surface angle (TTS) were evaluated using weight-bearing ankle radiographs.The median patient age was 66 years, and the mean follow-up duration was 46 ± 23 months. Two stage 2, 9 stage 3a, 30 stage 3b, and 11 stage 4 according to the Tanaka–Takakura classification were performed using DTOO. The JSSF scale improved significantly from 39.9 ± 13.8 before surgery to 87.2 ± 7.5 after surgery. Seven cases were fixed using a locking plate, and 45 cases were fixed using a circular external fixator. The TAS, MMA, TLS, TTA, and TTS significantly changed before and after DTOO.Radiological evaluation indicated that DTOO influences talar behavior during weight-bearing, and improves the clinical outcomes of AOA.     

膝关节ACL重建术研究进展

前交叉韧带（ACL）重建术作为治疗ACL损伤的有效治疗手段,近年来发展快速。该文围绕ACL损伤治疗方法,ACL重建术移植物选择、骨隧道制备和选择、移植物固定方式以及促进腱骨愈合方法等方面,综述膝关节ACL重建术的最新研究进展。     

Radial styloidectomy: a biomechanical study on stability of the wrist joint

We investigated the influence of radial styloidectomy on carpal alignment and examined translation of the wrist after sequentially increased styloidectomy of 8 cadaver wrists. The radial aspect of the scaphoid fossa of the distal radius was cut obliquely at 3, 6, and 10 mm from the radial styloid guided by real-time fluoroscopy. Radiographic analysis of the changes of carpal alignment was performed with the wrist in neutral position. Force-displacement curves from the neutral to the radioulnar and palmar-dorsal directions were obtained using a multi-axis testing machine. Results demonstrated no significant malalignment of the carpal bones after radial styloidectomy. Significantly increased radial translation (>40% reduction in stiffness), however, was observed due to the loss of radial articular contact after 6- and 10-mm radial styloidectomies. Significant ulnar and palmar carpal displacement also was noted after 6- and 10-mm radial styloidectomies, with 6 specimens demonstrating moderate ulnar and palmar translation and 2 demonstrating notable increased palmar and ulnar translations. We conclude that there is a definite risk of increased carpal instability with radial styloidectomy procedures. A styloidectomy of no more than 3 to 4 mm is recommended.     

Influence of anthropometric features on graft diameter in ACL reconstruction

Background

There is a paucity of literature regarding the influence of anthropometric features on the hamstring graft obtained in ACL reconstruction. This study was undertaken to assess the influence of anthropometric measurements on the graft diameter obtained at ACL reconstruction surgery within the European population. We hypothesise that anthropometric features do influence graft thickness in ACL reconstruction.

Materials and methods

Data from 121 consecutive patients who had undergone ACL reconstruction by the same surgeon using quadruple hamstring grafts were analysed. The body mass index (BMI), height and weight of these patients were correlated with the graft diameter obtained during surgery. Regression analysis was undertaken to assess the influence of individual anthropometric variables on the graft diameter.

Results

There were 121 patients with mean age of 32 years (14–55). There was a statistically significant positive correlation individually between the height and graft diameter (r = 0.38, p < 0.01) as well as between the body weight and graft diameter (r = 0.29, p < 0.01). However, when the body mass index was calculated, the correlation was not statistically significant (r = 0.08, p > 0.1). Regression analysis confirmed that BMI was not statistically significant as a predictor of hamstring graft diameter whereas height was statistically the most important predictor (F = 20.1; p < 0.01).This yielded the predictive equation, graft diameter = 4.5 + 0.02 x Ht (in cm).

Conclusion

Although body mass index did not significantly correlate, body height may be a predictive variable in predicting the graft diameter in ACL reconstruction and provide useful pre operative information.     

Comparison between bovine bone and titanium interference screws for implant fixation in ACL reconstruction: a biomechanical study

Introduction

The application of interference screws for the fixation of bone-patellar tendon-bone (BPTB) grafts is a well-established technique in anterior-cruciate ligament reconstruction. Interference screws derived from bovine compact bone are a biological alternative to metallic or biodegradable polymer interference screws.

Materials and methods

In 60 porcine specimens, the tibial part of an anterior-cruciate ligament reconstruction was performed using a BPTB graft. To secure the graft, either an 8-mm titanium interference screw or a self-made bovine interference screw (BC), or a commercial bovine compact bone screw (Tutofix^®) was used. The maximum failure load was determined by means of a universal testing machine with computer interface at a testing speed of 50 mm/min. In a second test series, cyclic sub-maximal load was applied to the test specimen from 40 to 400 N with a number of 1,000 load cycles and a frequency of 1 Hz. Subsequently, the maximum failure load was determined. The stiffness of the test specimen was investigated in both test series. Each type of interference screw was tested 10 times.

Results

A secure fixation of the grafts was achieved with all interference screws. In the experiments on the maximum load to failures, the titanium screws showed significantly higher failure loads than the Tutofix^® screws (P = 0.005). The stiffness of the grafts fixed with BC screws was significantly higher as compared to the fixation with Tutofix^® screws (P = 0.005). After cyclic sub-maximal loading, the maximum failure load of the titanium screws was significantly higher than that of the Tutofix^® screws (P = 0.033). The fixation of the BC screws showed a significantly higher failure load (P = 0.021) and stiffness (P = 0.032) than the Tutofix^® screw fixation. Except for two screw head fractures and two intra-tendinous graft ruptures, the failure mode was slippage in the interface between interference screw and bone plug.

Conclusion

Interference screws derived from bovine compact bone show similar good results as the titanium interference screws. Therefore, the safety and in vivo performance of products derived from xenogenic bone should be the focus of further investigations.     

The anatomy of the ACL and its importance in ACL reconstruction

The anterior cruciate ligament (ACL) anatomy is very significant if a reconstruction is attempted after its rupture. An anatomic study should have to address, its biomechanical properties, its kinematics, its position and anatomic correlation and its functional properties. In this review, an attempt is made to summarize the most recent and authoritative tendencies as far as the anatomy of the ACL, and its surgical application in its reconstruction are concerned. Also, it is significant to take into account the anatomy as far as the rehabilitation protocol is concerned. Separate placement in the femoral side is known to give better results from transtibial approach. The medial tibial eminence and the intermeniscal ligament may be used as landmarks to guide the correct tunnel placement in anatomic ACL reconstruction. The anatomic centrum of the ACL femoral footprint is 43 % of the proximal-to-distal length of lateral, femoral intercondylar notch wall and femoral socket radius plus 2.5 mm anterior to the posterior articular margin. Some important factors affecting the surgical outcome of ACL reconstruction include graft selection, tunnel placement, initial graft tension, graft fixation, graft tunnel motion and healing. The rehabilitation protocol should come in phases in order to increase range of motion, muscle strength and leg balance, it should protect the graft and weightbearing should come in stages. The cornerstones of such a protocol remain bracing, controlling edema, pain and range of motion. This should be useful and valuable information in achieving full range of motion and stability of the knee postoperatively. In the end, all these advancements will contribute to better patient outcome. Recommendations point toward further experimental work with in vivo and in vitro studies, in order to assist in the development of new surgical procedures that could possibly replicate more closely the natural ACL anatomy and prevent future knee pathology.     

Anterior displacement of the tibial tuberosity. An experimental biomechanical study of its effects on the femoro-patellar joint]

The anterior displacement of the tibial condyle was proposed as early as 1963 by P. Maquet as a therapeutic solution to treat femoropatellar arthritis. However, the benefits of such a procedure remain controversial. In this work, the effects of a 1. cm anterior displacement of the tibial condyle, with and without section of the patellar wings, have been studied on the knees of fresh corpses without osteoarthritis. The knees were tested in flexion from 10 to 70 degrees. The study dealt with the contact surfaces, pressures, and femoropatellar forces, which were analyzed with an original and efficient measurement system, with the Fuji Prescale Film as a sensor. This study showed that the femoropatellar contact has not been significantly modified by the displacement of the tibial condyle. We have noted only a slight decrease in the pressure after this type of surgery. These results are in contradiction with Marquet's results. In all cases, the anterior displacement of the tibial condyle with resection of both patellar wings produced the best results. These results suggest that displacing the tibial condyle anteriorly does not have the expected effects. The indication of such a surgical procedure must therefore be established only cautiously and after ruling out other therapeutic methods.     

前交叉韧带胫骨棘止点撕脱骨折不同内固定方式的生物力学研究

目的比较前交叉韧带(ACL)胫骨棘止点撕脱骨折四种常用内固定方法的生物力学性能。方法取正常成人新鲜膝关节标本16具,随机分为4组,每组4具；标本制作成ACL胫骨棘止点撕脱骨折后用4种不同内固定方法进行固定的模型：钢丝正向内固定组、钢丝反向内固定组、缝线内固定组及螺钉内固定组。标本屈曲30°位在MTS上机施加30、60,90N的持续牵拉力,模拟Lachman试验,用激光三维扫描仪在不同角度对膝关节进行扫描,采集实验数据,建立股骨、胫骨及膝关节结构模型。对各内固定组ACL的位移变化进行比较,数据采用析因分析的方法。结果施加30、60N的应力时,各组间ACL股骨和胫骨附着点间距变化无明显差异(P＞0．05)。在加载90N应力状态下,缝线内固定组股骨和胫骨附着点间距变化最小,平均为(4．8±1．7)mm(2．5～6．2mm),优于其它三组。螺钉内固定组与钢丝反内固定组间在ACL位移变化上差异无显著性意义(P=0．214),但均优于钢丝正内固定组(P＜0．05)。不同应力下钢丝正内固定组向前平均位移最大,平均为(7．2±1．3)mm(5．6～8．7mm)。结论缝线固定膝关节稳定性优于钢丝反内固定、螺钉内固定及钢丝正内固定；钢丝正内固定向前平均位移最大,膝关节稳定性最差。螺钉内固定与钢丝反内固定间比较差异无显著性意义。     

Double-bundle and double-tunnel ACL reconstruction with looped proximal tibial fixation

Double-bundle anterior cruciate ligament (ACL) reconstruction can be demanding and time consuming and requires twice as many implants, increasing both costs and possible complications. In this article, we present a new approach to double bundle ACL reconstruction: a biological fixation of the tibial side by means of a double tunnel and a U-shape passage of an anterior tibialis allograft, fixed into a double tunnel on the femoral condyle with 2 interference bioabsorbable screws. The technique is designed to combine 2 known procedures for the regular knee surgeon: the mono-tunnel technique and the medial-portal approach.     

Primary stability of various implants in tibial opening wedge osteotomy: a biomechanical study

 High tibial osteotomy (HTO) is an established method for treating varus gonarthrosis. The opening wedge HTO has some advantages over the lateral closed wedge technique. In this biomechanical study various systems of internal fixation of medial HTO were compared using an animal cadaver model (lower leg specimens from 1-year-old female domestic pigs). The first osteotomy (10°) was carried out and stabilized with a C-plate, an Arthrex spacer plate, or an AO tibial plate with or without bone graft. The resistance to axial stress was tested in a mechanical testing machine. Under lower axial stress (25, 50, 75, 100 N) the axial displacement between the various specimens did not show any significant differences. Under maximal axial force, the specimen fixed with the C-plate (F _max 2042 N) showed significantly better stability than the Arthrex plate (F _max 1687 N); P < 0.05. The AO plate (F _max 1612 N without bone graft and F _max 1583 N with bone graft) showed the lowest axial exposure to stress. Moreover, the influence of the osteotomy angle (7.5°, 10°, 12.5°, 15°) on axial stress resistance (F _max 2548, 2090, 1975, and 1740, respectively) was evaluated, and a direct correlation was found (R = 0.794, P < 0.05). Received: April 12, 2002 / Accepted: July 8, 2002 Offprint requests to: G. Spahn     

Ulnar shortening effect on distal radioulnar joint stability: a biomechanical study

PURPOSE: The ulnar-shortening procedure has been adopted widely to reduce pressure between the ulna and ulnar carpus in ulnocarpal abutment syndrome. The hammock-like structure of the triangular fibrocartilage complex (TFCC), which supports and connects the ulnocarpal and distal radioulnar joint (DRUJ), variably is torn in this condition. The degree to which the torn TFCC may be tensioned to restabilize the DRUJ with ulnar recession is uncertain. This study examined changes in the stabilizing effect of the ulnar-shortening procedure in several TFCC tear conditions. METHODS: Six fresh-frozen cadaver arms amputated at the midportion of the humerus were used. The skin, muscles, and capsuloligamentous structures below the elbow all were preserved. The ulna and humerus were affixed firmly to a custom mount that allowed 60 degrees of forearm rotation. An external fixator was attached to the distal ulna leaving space for a 10-mm resection of the ulna to allow progressive shortening. The radius was attached to a materials testing machine. The load-displacement curves were obtained while translating the distal radius dorsally or palmarly with respect to the ulna at 1.25 mm/s. Stiffness in dorsopalmar displacement was recorded at 1-mm intervals through 6 mm of length. These measurements then were compared with controls (0 mm shortening of the intact specimens) at 60 degrees pronation, neutral position, and 60 degrees supination. The tests then were repeated after sectioning either the dorsal or palmar portion of the radioulnar ligament (RUL) and then after complete sectioning of the RUL. Each portion was sectioned at its attachment to the ulnar fovea. RESULTS: The stiffness of the DRUJ increased significantly in all 3 rotatory positions after shortening the ulna. A shortening of 6 mm resulted in a 26% to 44% increase in DRUJ stiffness. The stiffness decreased after partial sectioning of the RUL but increased with further ulnar shortening in all 3 positions. The DRUJ stiffness with the partially sectioned RUL after a shortening of 3 to 6 mm was as large as that of the intact specimens. The stiffness of the DRUJ after the complete section of the RUL was significantly smaller than that of the intact specimens even after shortening of 6 mm. CONCLUSIONS: The ulnar-shortening procedure can stabilize the DRUJ by increasing intrastructural tension of the TFCC, only when the RUL is attached totally or partially to the ulnar fovea. If the RUL is avulsed completely then stability of the DRUJ no longer is obtained by the ulnar-shortening procedure.     

Effect of wrist position on distal radioulnar joint stability: A biomechanical study

We investigated distal radioulnar joint (DRUJ) stability in different wrist positions and examined the relative contribution of each ligamentous component of the triangular fibrocartilage complex (TFCC) to DRUJ stability. We used nine fresh‐frozen cadavers. The humerus and ulna were fixed at 90° elbow flexion. The radiocarpal unit was translated relative to the ulna in dorsopalmar directions with the wrist in five positions. Displacement of the unit was measured by an electromagnetic tracking device. Magnitudes of displacement were compared between different wrist positions in various sectioning stages: ulnocarpal ligament (UCL) sectioning, radioulnar ligaments (RUL) sectioning, and extensor carpi ulnaris (ECU) floor sectioning. Wrist position and sectioning stage significantly influenced the displacement. In intact wrists, the displacement in wrist extension was significantly lower than that in neutral. However, after UCL sectioning, there were no longer any significant differences. After RUL sectioning, the displacement in radial deviation was significantly lower than that in neutral. Following ECU floor sectioning, there were no longer any significant differences. Thus, in intact wrists, DRUJ stability in wrist extension is likely due to tightening of the UCL. After complete RUL sectioning, DRUJ is stabilized in radial deviation due to tightening of the ECU floor. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1247–1251, 2014.     

Bicondylar tibial plateau fractures: a biomechanical study

The optimal treatment of bicondylar tibial plateau fractures remains controversial. The current study was designed to answer the following questions: (1) can a lateral fixed angle plate provide similar construct stability to dual plating techniques and (2) does the size of the medial buttress plate used in dual plating techniques have an effect on construct stability? Bicondylar tibial plateau fractures were created, reduced, and instrumented in a matched pair design using a cadaveric simulated bicondylar tibial plateau fracture model. Tibias were instrumented with one of three constructs: a lateral periarticular plate and posteromedial small fragment dynamic compression plate, a lateral periarticular plate and posteromedial (1/3)-tubular plate, or a lateral fixed angle plate. Biomechanical testing was done to determine construct stiffness, maximum load to failure, and medial condylar displacement for each of the three constructs. There was no significant difference measured between the two dual plating constructs and the lateral fixed angle plate for overall construct stiffness or with respect to medial condylar fragment displacement. A lateral fixed angle plate may have clinical applications in the treatment of bicondylar tibial plateau fractures.     

Preoperative determination of tibial nail length: An anthropometric study

Objective: To assess the correlation between five anthropometric parameters and the distance from tibial tuberosity to medial malleolus in 100 volunteers. Methods: Six anthropometric parameters were measured in 50 male and 50 female medical students using a metallic scale: medial knee joint line to ankle joint line (K-A), medial knee joint line to medial malleolus (K-MM), tibial tuberosity to ankle joint (TT-A), tibial tuberosity to medial malleolus (TT- MM), olecranon to 5th metacarpal head (O-MH) and body height (BH). Nail size predicted based upon TT-MM measurement was chosen as ideal nail size. A constant was derived for each of the six anthropometric parameters which was either added or subtracted to each measurement to derive nail size. A regression equation was applied to BH measurements. Nail sizes calculated were compared with that obtained from TT-MM measurement and accuracy was evaluated. Accuracy of O-MH and BH regression equations recommended by other authors were calculated in our data. Results: Adding 11 mm to TT-A distance had highest accuracy (81%) and correlation (0.966) in predicting nails correctly. Subtracting 33 mm from K-MM measurement and 25 mm from K-A distance derived accurate sizes in 69% and 76% respectively. Adding 6 mm to O-MH distance had a poor accuracy of 51%. Nail size prediction based upon body height regression equation derived correct nail sizes in only 34% of the cases. Regression equation analysis by other authors based on O-MH and BH distances yielded correct sizes in 11% and 5% of the cases respectively. Conclusion: TT-A, K-A and K-MM measurements can be used simultaneously to increase accuracy of nail size prediction. This method would be helpful in determining nail size preoperatively especially when one anatomic landmark is difficult to palpate.     

前交叉韧带重建术中胫骨侧止点无撞击区的定位研究

目的探讨前交叉韧带(ACL)重建术中胫骨隧道无撞击重建区的定位。方法选用10具正常新鲜冷冻尸体膝关节标本,膝关节完全伸直时,标记髁间窝顶延长线和ACL胫骨附着处的交点。膝关节屈曲90°时,测量ACL胫骨附着处上标记点与ACL前缘间的距离及标记点与胫骨棘间区后缘间的距离。然后,再测量标记点前部分的前后径、后部分的前后径和内外径,并计算后部分的面积。结果由ACL胫骨附着处前缘到胫骨棘间区后缘的前后径平均为(21.40±1.17)mm。ACL胫骨附着处标记点前部分的前后径平均为(8.90±0.74)mm(占总前后径的41.59%)。胫骨附着处标记点后部分的前后径平均为(12.50±0.85)mm(占总前后径的58.41%),内外径平均为(10.65±0.97)mm,面积平均为(133.80±21.01)mm2。结论ACL胫骨附着处上标记点的后部分是胫骨隧道无撞击区,位于胫骨棘间区的后缘中点与该点前12.50mm之间,在该区域行ACL重建可以避免移植物与髁间窝顶部的撞击。绝对撞击区位于ACL胫骨附着部前缘与其后8.90mm之间,应尽量避免在此区域内定位胫骨隧道。     

Biomechanical study of ACL reconstruction grafts

There are no published studies describing the strength quadrupled gracilis tendon alone and quadrupled semitendinosus tendon alone in the configuration used for anterior cruciate ligament (ACL) reconstruction. The primary objective was to compare the mechanical properties of grafts used for ACL reconstruction during a tensile failure test. The secondary objective was to evaluate the effect of uniform suturing on graft strength. Fifteen pairs of knees were used. The mechanical properties of five types of ACL grafts were evaluated: patellar tendon (PT), sutured patellar tendon (sPT), both hamstring tendons (GST4), quadrupled semitendinosus (ST4), and quadrupled gracilis (G4). Validated methods were used to perform the tensile tests to failure and to record the results. Student's t‐test was used to compare the various samples. The maximum load to failure was 630.8N (± 239.1) for the ST4, 473.5N (± 176.9) for the GST4, 413.3N (± 120.4) for the sPT, and 416.4N (± 187.7) for the G4 construct. Only the ST4 had a significantly higher failure load than the other grafts. The sPT had a higher failure load than the PT. The ST4 construct had the highest maximum load to failure of all the ACL graft types in the testing performed here. Uniform suturing of the grafts improved their ability to withstand tensile loading. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1188–1196, 2015.