Single Tendon Research Articles

Tendons Arrangement Effects on Reinforced Concrete Frames under Blast Loading

The tendons arrangement effects on the response of reinforced concrete frame experiencing blast loads is investigated in this paper. The structure is modeled using nonlinear finite elements employing a bilinear hysteretic model. So that elements are used so that yielding of the structures could be accurately modeled and captured. The frame is analyzed using a non-linear, elastic-plastic finite element program written in code MATLAB. Six tendon architectures were investigated. A single tendon was placed between different floors and its effects investigated. From the obtained results, the ideal case which causes a reduction in the maximum displacement and the amount of permanent deflection without increase in the maximum structural shear forces greatly is obtained.

Etiology and Treatment of Pediatric Trigger Finger: Possible Application of Partial V-shaped Resection of the Central Part of Flexor Digitorum Superficialis through our Case Presentation

To the Editor, The purpose of this case presentation is to discuss the etiology and the efficacy of a standardized surgical technique in the treatment of symptomatic trigger fingers in pediatric patients. A 7-year-old boy complained that he could not extend the proximal interphalangeal (PIP) joint of his left middle finger due to symptomatic locking and clicking, especially in the morning, for 4 months already. There was no obvious past history concerning his complaint except practicing the horizontal bar gymnastics as his sports activity. The X-ray films obtained at the initial consultation showed no abnormality of his middle finger. Corticosteroid (a total 0.3 ml of triamcinolone acetonide; Kenacort-A) was injected under the A1 pulley and splinting was carried out. As the symptom did not improve by this conservative treatment, we treated him surgically 3 months after his first consultation. During the surgery, no tightness or thickening of the A1 pulley was observed (Fig. 1a). After dividing the A1 pulley, an enlarged flexor digitorum superficialis (FDS) tendon due to adhesion between both FDS tendon slips was observed at the chiasma area (Fig. 1b, c). As triggering seemed to occur at the level of the FDS tendon decussation, the central part of both FDS tendon slips was resected (Fig. 1d). There was a specific tendon lesion, including fusiform thickening and inflammatory cellular infiltration (Fig. 2). He was able to extend the PIP joint through a full range. At the latest follow-up examination 1 year later, he had no complaints, and there were no serious complications such as nerve transaction, bowstringing, or recurrence. Although the etiology of symptomatic pediatric trigger finger in this patient was unclear, environmental factors such as chronic mechanical stress rather than congenital factors seemed to be the plausible cause. Previous reports concluded that pediatric trigger finger may be safely and predictably treated by surgical release of the proximal part of the A2 pulley in addition to the A1 pulley and resection of a single FDS tendon slip [1, 2]. We recommended partial V-shaped resection of the central part of FDS over ulnar superficialis slip resection in pediatric patients, because PIP flexion contracture does not seem to be a serious problem in the pediatric population compared to the adult one. Fig. 1 Intraoperative findings. a Neither tightness nor thickening of the A1 pulley was observed. The arrow shows the A1 pulley. b, c After dividing the A1 pulley, an enlarged FDS tendon due to adhesion between both FDS tendon slips was observed at the chiasma ... Fig. 2 Microphotograph of part of the FDS specimen showing fusiform thickening and inflammatory cellular infiltration

Biceps Brachii Tendon Ruptures: A Review of Diagnosis and Treatment of Proximal and Distal Biceps Tendon Ruptures

The biceps brachii is a unique muscle with 2 proximal tendons and a single distal tendon. Although these tendons are part of the same muscle, they have significantly different functions. It is hypothesized that the long head of the biceps acts as a pain generator in the shoulder, though the biomechanical function is still under debate. Conversely, the distal biceps tendon is the major supinator of the forearm and serves a secondary flexor. As such, injuries to these tendons must be evaluated independently. Biceps brachii ruptures most often occur in middle-aged men following a traumatic event. Injuries to the long head of the biceps are primarily treated nonoperatively with adequate results. Injuries of distal tendon occur less often, but are receiving significant attention in the literature in regard to treatment options. Surgical repair of distal biceps ruptures is indicated in patients who want to restore supination strength and endurance. It is unclear which operative technique is superior, although the most recent data suggest increased strength of the cortical button repair. This article provides a comprehensive review of both proximal and distal biceps brachii ruptures in addition to our treatment algorithm.

Molecular structure of tail tendon fibers in TIEG1 knockout mice using synchrotron diffraction technology

The purpose of this study was to characterize the effect of TIEG1 on the molecular structure of collagen within tail tendon fibers using 3-mo-old female C57BL/6 wild-type (WT) and TIEG1 KO mice. Synchrotron X-ray microdiffraction experiments were carried out on single tendon fibers extracted from the WT and TIEG1 KO dorsal tail tendon. The fibers were scanned in the radial direction, and X-ray patterns were obtained. From these patterns, the meridional direction was analyzed through X-ray intensity profile. In addition, collagen content was investigated using hydroxyproline assays, and qualitative real-time PCR experiments were performed on RNA isolated from fibroblasts to examine specific gene expression changes. The results showed different X-ray diffraction patterns between WT and TIEG1 KO tendon fibers, indicating a disorganization of the collagen structure for the TIEG1 KO compared with WT mice. Furthermore, the analyses of the X-ray intensity profiles exhibited a higher (23 A) period of collagen for the TIEG1 KO compared with the WT mice. The results of the hydroxyproline assays revealed a significant decrease in the TIEG1 KO compared with WT mice, leading to a decrease in the total amount of collagen present within the TIEG1 KO tendons. Moreover, qualitative real-time PCR results showed differences in the expression profiles of specific genes known to play important roles in tendon fiber development. These data further elucidate the role of TIEG1 on tendon structure and could explain the previous defects in the structure-function relationship found for TIEG1 KO tendon fibers.

Patellafraktur nach MPFL-Rekonstruktion bei femoropatellarer Instabilität

We report on a 20-year-old female patient with a fracture of the patella after she fell on"black ice" 2 months after medial patellofemoral ligament (MPFL) reconstruction for patellar instability. For reconstruction of the MPFL, a single hamstring tendon graft was passed through the medial intermuscular septum and was fixed to the superomedial pole of the patella. The fracture was reduced by wire cerclage. Intraoperatively it was shown that the fracture line went through the patellar drill hole. No complications occurred during the further postoperative period. The literature contains only a few case reports describing fractures of the patella after MPFL reconstruction without any specific trauma. In this case, an interruption in blood supply with resulting avascular necrosis was suspected as a causal factor.

El İşaret Parmağının Ekstensörlerinin Anatomik Özellikleri

Objective: Extensor indicis proprius (EIP), the extensor medii proprius (EMP) and the extensor indicis medii proprius (EIMP) are important tendons in the surgery of hand as a graft, apart from performing the function of extension. In cases which require surgical treatment of the hand like trauma, rheumatoid arthritis, ulnar nerve palsy, and hypoplasia of the thenar muscle, the EIP, the EMP and the EIMP are suitable muscles for tendon transfer operations. Material and Methods: The variations of the extensor tendons to the index finger were examined in fifty-four dissected hands. Results: The most common pattern of the tendons was a single extensor digitorum indicis (ED-indicis) and a single EIP. The EIP was observed as a single tendon in 87.03% of the specimens, and as a double tendon in 12.96% of them. The EMP was seen in 24.07% of the specimens. In one hand, the muscle had a shared belly with the EMP and the EIMP. Conclusion: The existence of the supernumerary tendons was more frequently encountered at the ulnar side of the ED-indicis than at the radial side. These extra tendons may be of great value in cases of traumatized hands which require tendinoplasty.

Rotary Instability after Anterior Cruciate Ligament Reconstruction with Single BTB Tendon

Purpose: To analyze both the functional restoration and recovery of rotational and anterior-posterior stability after a single bundle ACL reconstruction using a BTB tendon. Materials and Methods: A total of 52 patients were evaluated with an average follow up period of 32 months. A Lachman test, KT- 2000 arthrometer, and Pivot shift test were performed to analyze the AP and rotational stability of the patients. The IKDC and Lysholm score was then used to evaluate the clinical results of the patients. The correlation between femoral tunnel angle and recovery of rotational stability was evaluated to determine the association between the two variables. This study also evaluated how the recovery of rotational stability affects the functional recovery of the patients. Results: At the final follow up, the results indicated significant improvement according to the negative Lachman tests in 40 cases (76%), with an average of 2.92 mm anterior translation in the KT-2000 arthrometer and negative Pivot shift tests in 41 cases (79%) (p, whereas Group B showed . Conclusion: Decreasing the inclination of the BTB tendon using a transtibial femoral tunnel angle at either 10'30 or 1'30 will result in an excellent clinical outcome by achieving both anterior and rotational stability when operating a single bundle ACL reconstruction.

An anatomic study on the junctura tendinum in the 4th intermetacarpal space and its clinical implication

We report results of anatomic study in the fourth intermetacarpal space, focusing on the pattern of junctura tendinum and variations of extensor tendons of the little finger with its clinical implication on snapping of the little finger. Fifty unpaired cadaveric hands were dissected from the wrist to the middle phalanx of the ring and little fingers. The type of junctura tendinum was judged based on Von Schroder's classification and the relationship with EDC were recorded. EDC to the little finger and EDM were dissected and the numbers were recorded. Forty six hands (92%) exhibited a junctura tendinum in the fourth intermetacarpal space and it was Type III in 42 hands (84%). The EDC-little finger was absent in 76% (38 of 50 hands). When present, EDC-little finger originated most commonly as single thin tendon. The absence of an EDC-little finger was associated with increased incidence of Type III junctura tendinum (37 of 38 hands). An EDM was present in all 50 hands running from the fifth dorsal compartment. Based on these clinical and anatomic studies, we considered that the snapping of the little finger is more likely subluxation of junctura tendinum rather than subluxation/dislocation of EDC of the little finger.

Degeneration of the Long Biceps Tendon: Comparison of MRI With Gross Anatomy and Histology

The objective of our study was to relate alterations in biceps tendon diameter and signal on MR images to gross anatomy and histology. T1-weighted, T2-weighted fat-saturated, and proton density-weighted fat-saturated spin-echo sequences were acquired in 15 cadaveric shoulders. Biceps tendon diameter (normal, flattened, thickened, and partially or completely torn) and signal intensity (compared with bone, fat, muscle, and joint fluid) were graded by two readers independently and in a blinded fashion. The distance of tendon abnormalities from the attachment at the glenoid were noted in millimeters. MRI findings were related to gross anatomic and histologic findings. On the basis of gross anatomy, there were six normal, five flattened, two thickened, and two partially torn tendons. Reader 1 graded nine diameter changes correctly, missed two, and incorrectly graded four. The corresponding values for reader 2 were seven, one, and five, respectively, with kappa = 0.75. Histology showed mucoid degeneration (n = 13), lipoid degeneration (n = 7), and fatty infiltration (n = 6). At least one type of abnormality was found in each single tendon. Mucoid degeneration was hyperintense compared with fatty infiltration on T2-weighted fat-saturated images and hyperintense compared with magic-angle artifacts on proton density-weighted fat-saturated images. MRI-based localization of degeneration agreed well with histologic findings. Diameter changes are specific but not sensitive in diagnosing tendinopathy of the biceps tendon. Increased tendon signal is most typical for mucoid degeneration but should be used with care as a sign of tendon degeneration.

Biomechanical evaluation of using one hamstrings tendon for ACL reconstruction: a human cadaveric study

Harvesting both the semitendinosus and gracilis tendons for anterior cruciate ligament (ACL) reconstruction has a negative impact on muscle strength as well as knee function and stability. With a new "All-inside" technique, using only one hamstrings tendon (semitendinosus or gracilis) is possible because of a reduction in length requirements. The research question of this in vitro study was whether the use of only one hamstrings tendon (semitendinosus or gracilis) could restore knee kinematics and in situ force in the ACL to the level of an intact knee.Ten human cadaveric knees were tested in the following conditions: (1) intact, (2) ACL-deficient, and (3) ACL reconstruction with the "All-inside" technique using the (a) single semitendinosus tendon graft, or (b) single gracilis tendon graft. Using a robotic testing system, external loads, i.e. (1) an anterior tibial load of 134-N and (2) combined rotatory loads of 10-Nm valgus and 5-Nm internal tibial torques, were applied. The multiple degrees of freedom knee kinematics and the in situ forces in the ACL and ACL grafts were determined. In response to a 134-N anterior tibial load, the use of either graft could restore anterior tibial translation to within 1.3 mm of the intact knee. The in situ forces in the two grafts were not significantly different from those of the intact ACL. Under the combined rotatory loads, both grafts could restore knee kinematics as well as the in situ force in the grafts to the level of the intact ACL. The "All-inside" technique using either the semitendinosus or gracilis tendon for ACL reconstruction could satisfactorily restore time-zero knee kinematics and the in situ forces in either graft to those for the intact ACL, supporting clinical findings.

Bifid insertion of the distal biceps brachii tendon with isolated rupture: Magnetic resonance findings

Rupture of the distal biceps brachii tendon is greatly outnumbered by rupture of the proximal attachment of the long head from the bicipitolabral anchor at the superior glenoid, with rupture of the origin of the proximal tendon of the short head of biceps an exceedingly uncommon injury. 1 Athwal G.S. Steinmann S.P. Rispoli D.M. The Distal Biceps Tendon: Footprint and Relevant Clinical Anatomy. J Hand Surg [Am]. 2007; 32: 1225-1229 Abstract Full Text Full Text PDF PubMed Scopus (147) Google Scholar , 2 Bernstein A.D. Breslow M.J. Jazrawi L.M. Distal biceps tendon ruptures: a historical perspective and current concepts. Am J Orthop. 2001; 30: 193-200 PubMed Google Scholar , 3 DiChristina D.G. Lustig K.A. Rupture through the short head of the biceps muscle belly. A case report. Clin Orthop Relat Res. 1991; 277: 139-141 Google Scholar A recent case of a bifurcated distal biceps tendon demonstrating selective disruption of a single tendon bundle has been reported that was surgically confirmed and subsequently underwent successful primary repair. 4 Eames M.H. Bain G.I. Fogg Q.A. van Riet R.P. Distal biceps tendon anatomy: a cadaveric study. J Bone Joint Surg Am. 2007; 89: 1044-1049 Crossref PubMed Scopus (147) Google Scholar If the clinical scenario demands surgical restoration due to functional disability, then accurate preoperative detection is paramount because this injury may be confused with a partial thickness tear of a nonbifurcated distal biceps tendon or a distal musculotendinous junction strain, both which are typically managed conservatively.

A Prospective Comparison of Postoperative Pain and Medication Use Between Single and Double Bundle Anterior Cruciate Ligament (ACL) Reconstruction (SS-45)

There are several studies in the ACL literature comparing the clinical outcomes, such as stability and function, of double and single bundle ACL reconstructions. However, there is little known about more immediate post-operative outcomes such as patient pain and medication use. The purpose of this study was to obtain preliminary data comparing pain levels and medication consumption during the first 14 days post-operative between patients receiving a single versus double bundle hamstring tendon ACL reconstruction. Two groups: (1) Single-bundle group (S)-patients enrolled in a randomized clinical trial investigating post-operative immobilization following single-bundle reconstruction and (2) Double-bundle group (D)-a consecutive series of patients receiving a double-bundle ACL reconstruction. Both groups completed a pain and medication log book for 14 days after surgery. Visual analoge scores (VAS) were recorded (0 mm=no pain to 100 mm=worst pain) at: 8am and 8pm for the first two days postoperative, and 5pm for days 3-14 postoperative. Patients also recorded the type of medication consumed and time of consumption. For analysis, medications were categorized into: a) opioids-oral, b) opioids-injected, c) non-steroidal anti-inflammatories (NSAIDs), d) acetaminophen, and e) other (i.e. antiemetic). Patients in both groups were not braced post-operatively. Two surgeons performed both procedures and patients were examined within 1 month postoperative. Thirty-one patients (19 male, 12 female) with a mean (SD) age of 29.2 (5.9) years underwent single bundle ACL reconstruction and 14 patients (9 male, 5 female) with a mean (SD) age of 21.7 (5.9) years had a double bundle ACL reconstruction. Pain scores were lower for the single bundle group at all intervals during the first 14 days post-operative except the evening of surgery (Mean [SD]: S=31.4 [21.1] and D=30.0 [21.7]). The greatest mean difference in VAS pain scores between groups was seen on Day 1am post-operative (Mean difference=13.1; p=0.051, 95% CI 0.035, 26.1) and on Day 2am (mean difference=13.8; p=0.077, 95% CI −1.57, 29.2). Regardless of procedure, the greatest pain reported was on the evening of Day 1 post-operative (Mean [SD]: S=50.9 [21.2] and D=57.4 [18.2]; mean difference = 6.5; p=0.331, 95% CI −6.7, 19.6). Oral opioid consumption was slightly higher in the double bundle group on Day 1 (Mean number of pills [SD]: S=6.7 [2.9] and D=9.4 [1.9]) and on Day 2 post-operative (S=5.2 [3.0] and D=7.8 [3.1]). However, the single bundle patients consumed more injectable opioids on the day of surgery (Mean [SD] Morphine: S=7.7 [16.2] mg and D=6.2 [7.5] mg; and Mean [SD] Fentanyl: S=13.7 [24.8] mcg and D=7.1 [26.7] mcg). NSAID and acetaminophen consumption was the same between the two groups at all intervals. The most common medication in the ‘other' category was gravol for both groups. The results of this preliminary study suggested that patients who had double bundle ACL reconstruction had higher pain levels during the first 14 days post-operative than patients who had single bundle ACL reconstruction. Despite the higher pain levels, medication consumption was similar between the two groups.

Postoperative Pain And Medication Use: Single Versus Double Bundle Anterior Cruciate Ligament (acl) Reconstruction

PURPOSE: Several studies have compared clinical outcomes for double and single bundle ACL reconstructions. However, little is known about immediate post-operative outcomes such as patient pain and medication use. The purpose was to obtain preliminary data on pain levels and medication use during the first 14 days post-operative between patients having a single versus double bundle hamstring tendon ACL reconstruction. METHODS: Two groups: (1) Single-bundle(S) - patients enrolled in a randomized clinical trial investigating post-operative immobilization following single-bundle ACL reconstruction and (2) Double-bundle(D) - a consecutive series of patients receiving a double-bundle ACL reconstruction. Visual analog scores (VAS) were recorded (0mm = no pain to 100mm = worst pain) at: 8am and 8pm for the first two days and 5pm for days 3-14 postoperative. Patients also recorded the type of medication consumed and time of consumption. Patients in both groups were not braced post-operatively. RESULTS: Thirty-one patients (19 male, 12 female) with a mean (SD) age of 29.2 (5.9) years underwent single bundle reconstruction and 17 patients (10 males, 7 female) with a mean (SD) age of 24.3 (8.8) years had a double bundle reconstruction. Pain scores were lower for the single bundle group at all intervals during the first 14 days post-operative except the evening of surgery, Day 9 and Day 11 (Mean (SD): S=31.4 (21.1); 26.4 (20.9); 21.9 (18.9), respectively and D=30.4 (23.3); 21.3 (19.3); 20.7 (15.2), respectively). The greatest mean difference in pain scores between groups were seen on Day 1am (mean difference=12.4; p=0.050, 95% CI -0.023, 24.9) and on Day 2am (mean difference=12.6; p=0.076, 95% CI -1.39, 26.8). Regardless of procedure, the greatest pain was Day 1pm (mean (SD): S=50.9 (21.2) and D=53.4 (20.1); mean difference=2.5; p=0.701, 95% CI -10.2, 15.1). With respect to medication use: oral and injectable opioids, NSAIDs, and acetaminophen consumption were similar between the two groups at all intervals. CONCLUSIONS: The results of this study suggested that patients who had double bundle ACL reconstruction had higher pain levels during the first 14 days post-operative than patients who had single bundle ACL reconstruction. Despite the higher pain levels, medication consumption was similar between the two groups.

Reconstruction of Open Contaminated Achilles Tendon Injuries With Soft Tissue Loss

Open achilles tendon injuries, present a complex problem to the treating surgeon especially if associated with tendon and soft tissue loss. We present eight such patients treated with tendon repair/reconstruction and reverse flow sural artery flap for soft tissue cover. Eight patients (age, 12-64 years) with a spectrum of open tendo-achilles injuries of acute and chronic (infected), including loss of tendon of up to 10 cm, tendon defects with no distal attachment and one with partial loss of the calcaneum were treated between November 2005 and July 2006. Two of them had significant medical comorbid factors. The skin defect measured after debridement ranged from 6 x 5 cm to 15 x 10 cm. The tendon injuries were sutured directly when possible or sutured to bone if avulsed from the calcaneum. They were otherwise reconstructed using the central part of the proximal segment. A reverse sural artery was used to provide soft tissue cover. All flaps survived. All patients had a normal gait, were able to stand on tip toes, had active plantar flexion and had returned to their original occupation 4 months after reconstruction. They had full range of movement at the ankle. One diabetic patient had terminal necrosis of the flap that required a split skin graft. He developed a late infection which did not compromise the functional result. In the management of complex tendo-achilles injuries with tendon and soft tissue loss, radical debridement, single stage tendon reconstruction, and reverse flow sural artery flap gives good functional outcome. This gives consistent results across a spectrum of open tendo-achilles injury.

Mechanical properties of the long‐head of the biceps tendon are altered in the presence of rotator cuff tears in a rat model

Rotator cuff tears are disabling conditions that result in changes in joint loading and functional deficiencies. Clinically, damage to the long-head of the biceps tendon has been found in conjunction with rotator cuff tears, and this damage is thought to increase with increasing tear size. Despite its importance, controversy exists regarding the optimal treatment for the biceps. An animal model of this condition would allow for controlled studies to investigate the etiology of this problem and potential treatment strategies. We created rotator cuff tears in the rat model by detaching single (supraspinatus) and multiple (supraspinatus + infraspinatus or supraspinatus + subscapularis) rotator cuff tendons and measured the mechanical properties along the length of the long-head of the biceps tendon 4 and 8 weeks following injury. Cross-sectional area of the biceps was increased in the presence of a single rotator cuff tendon tear (by approximately 150%), with a greater increase in the presence of a multiple rotator cuff tendon tear (by up to 220%). Modulus values decreased as much as 43 and 56% with one and two tendon tears, respectively. Also, multiple tendon tear conditions involving the infraspinatus in addition to the supraspinatus affected the biceps tendon more than those involving the subscapularis and supraspinatus. Finally, biceps tendon mechanical properties worsened over time in multiple rotator cuff tendon tears. Therefore, the rat model correlates well with clinical findings of biceps tendon pathology in the presence of rotator cuff tears, and can be used to evaluate etiology and treatment modalities.

Viscoelastic behavior of discrete human collagen fibrils

Whole tendon and fibril bundles display viscoelastic behavior, but to the best of our knowledge this property has not been directly measured in single human tendon fibrils. In the present work an atomic force microscopy (AFM) approach was used for tensile testing of two human patellar tendon fibrils. Fibrils were obtained from intact human fascicles, without any pre-treatment besides frozen storage. In the dry state a single isolated fibril was anchored to a substrate using epoxy glue, and the end of the fibril was glued on to an AFM cantilever for tensile testing. In phosphate buffered saline, cyclic testing was performed in the pre-yield region at different strain rates, and the elastic response was determined by a stepwise stress relaxation test. The elastic stress-strain response corresponded to a second-order polynomial fit, while the viscous response showed a linear dependence on the strain. The slope of the viscous response showed a strain rate dependence corresponding to a power function of powers 0.242 and 0.168 for the two patellar tendon fibrils, respectively. In conclusion, the present work provides direct evidence of viscoelastic behavior at the single fibril level, which has not been previously measured.

Achilles Tendon Allograft Reconstruction of the Fibular Collateral Ligament and Posterolateral Corner

The purpose of this study was to investigate the functional and clinical outcomes of a consecutive series of patients who underwent fibular collateral ligament (FCL) and posterolateral corner (PLC) reconstruction by use of a single Achilles tendon allograft construct. Patients were identified through prospective sports medicine databases at 2 academic institutions. Only patients who had undergone FCL and PLC reconstruction (as opposed to repair) were included. All patients followed a standard postoperative rehabilitation protocol. Various patterns of combined ligament injuries were included and divided into 2 groups (2 ligament v multiligament). Functional and clinical outcomes were assessed by clinical examination, Lysholm scores, and International Knee Documentation Committee subjective scores. Statistical analysis was performed by use of Wilcoxon paired rank-sum tests and multivariate regression. We identified 16 knees in 16 patients, with a minimum of 2 years' follow-up. There were 13 men and 3 women. The mean age was 30 years (range, 19 to 61 years). The mean length of clinical follow-up was 30 months (range, 24 to 75 months). The mean International Knee Documentation Committee subjective scores were 80 points and 80 points (P = .79) in the 2-ligament and multiligament groups, respectively, and the mean Lysholm scores were 90 points and 89 points (P = .96), respectively. Age (P = .41), gender (P = .84), and interval between injury and surgery (P = .72) did not affect the clinical and functional outcomes between the 2 groups. Arthrofibrosis requiring manipulation developed in 1 patient. Residual varus laxity (1+) was noted in 4 patients, none of whom displayed functional instability. No patient has required revision reconstruction to date. We describe a novel technique that takes into account the main static PLC stabilizers (FCL, popliteofibular ligament, and posterolateral capsule) that has not been previously reported. Our series showed no significant differences in clinical and functional outcomes between 2-ligament and multiligament PLC-based reconstructions. However, given the heterogeneity and small sample size of our study group, it is difficult to draw qualitative conclusions. Level IV, therapeutic case series.

ACL reconstruction: Can the transtibial technique achieve optimal tunnel positioning? A radiographic study

Placement of the femoral tunnel performing ACL reconstruction can be performed using a transtibial technique. Theoretically, this procedure bears the risk of a vertical placement of the femoral tunnel in the intercondylar notch. We assessed tunnel positioning radiographically using the transtibial technique. Postoperative anteroposterior and lateral knee radiographs in 30 patients/knees (19 men, 11 women) undergoing ACL reconstruction using a 4-strand single bundle hamstrings tendon graft by a single surgeon, using a standardized technique, were retrospectively evaluated. Mean age at the time of operation was 27 years (range 16–42). Two experienced independent orthopaedic fellows, not having participated in the management of those patients, performed the radiographic measurements. Mean graft inclination angle was 19° (SD 2). In the sagittal plane the femoral tunnel was placed at 85% (SD 4), posteriorly across Blumensaat's line and the tibial tunnel at 43% (SD 3). Intraobserver Spearman–Brown coefficient was 0.78 and the intraclass correlation was 0.70 (substantial agreement). The values presented are consistent with optimal tunnel positioning according to anatomic and clinical studies. Standardized surgical technique and anatomical landmarks can achieve optimal tunnel positioning using the transtibial technique for ACL reconstruction.

Dynamic Behavior of SMA Actuated Catheter

Introduction: While catheters have proven effective in numerous cardiovascular procedures, their functionality and versatility can be greatly improved by incorporating active steering capabilities to the catheter tip. Shape memory alloy (SMA) actuation is ideally suited to this application, as these materials offer superior power density, energy density and biocompatibility. In this research, we investigate the transient behavior of an SMA-actuated active catheter to optimize its design and enable precise computer-controlled navigation. Methods: The active catheter prototype consists of a central beam actuated by a single SMA tendon, both enclosed by an outer Teflon sleeve. Joule heating is used to generate tip deflections, which are measured in real time using a dual-camera imaging system. SMA actuation is described using the Seelecke-Muller-Achenbach single-crystal model whose parameters are experimentally derived from stress-strain characteristics of the SMA tendon measured at different temperatures. These characteristics are used to optimize the design parameters of the catheter to maximize the bending response. The effects of outer sleeve thickness on the transient behavior of the catheter are also studied. Results: The catheter’s bending mechanics are described using a circular arc model, which is experimentally validated. Catheter actuation is found to be slower with increased sleeve thickness, as explained by heat transfer analysis. Dynamic simulation of the system model shows excellent correlation to experimental data for low frequency actuation.

High frequency tendon reflexes in the human soleus muscle

Tendon reflexes have been often used in studies of the human nervous system in health and disease. They have been investigated either in response to single tendon taps or to long duration vibrations. Tendon reflexes are described here in response to a high frequency vibration burst (3 cycles of a 100 Hz sine wave) applied to the Achilles tendon of standing subjects, either in quiet stance or during a forward leaning posture. The electromyogram from the soleus muscle usually showed three components separated by 10 ms which were interpreted as being three reflexes, each reflex induced by each of the three cycles in a burst. This result indicates that soleus tendon reflexes can respond in fast succession in a phasic manner when a brief high frequency vibration is applied to the Achilles tendon. This occurs in spite of possible depression of the Ia to motoneuron synapses and the long after hyperpolarization of the motoneurons. An interpretation of the results is that motoneurons from different subsets of the motoneuron pool respond to different cycles of the sinusoidal vibratory burst.