Biomechanical Analysis of Ideal Knee Flexion Angle for ACL Graft Tensioning Utilizing Multiple Femoral and Tibial Tunnel Locations.

Anterior cruciate ligament (ACL) graft failure rate has been reported to be greater than 5% at 5 years. Our study evaluated ACL excursion with anatomic and nonanatomic femoral and tibial tunnels to determine optimal flexion angle to tension the ACL to minimize excursion. Ten cadaveric knee specimens were used. The ACL was sectioned and the femoral and tibial attachments were marked. A 1/16-inch drill created a tunnel in the center of the ACL footprint on the tibia and femur and additional tunnels were made 5 mm from this. A suture was passed through each tunnel combination and attached to a string potentiometer. The knee was ranged from full extension to 120 degrees of flexion for 10 cycles while mounted in a custom fixture. The change in length (excursion) of the suture during movement was recorded for each combination of femoral and tibial tunnels. Anatomic reconstruction of the ACL with tunnel placement in the center of the femoral and tibial footprint did not result in an isometric graft, with excursion of the ACL during knee motion of 7.46 mm (standard deviation [SD]: 2.7mm), greatest at 2.84 degrees of flexion (SD: 4.22). The tunnel combination that resulted in the least excursion was a femoral footprint 5 mm anterior to the femoral and 5 mm posterior to the tibial footprint (4. 2mm, SD: 1.37 mm). The tunnel combination that resulted in the most excursion utilized femoral footprint 5 mm proximal to the femoral and 5 mm posterior to the tibial footprint (9.81 mm, SD: 2.68 mm). Anatomic ACL reconstruction results in significant excursion of the ACL throughout motion. If not tensioned properly, the ACL can stretch during range of motion, potentially leading to rerupture. To prevent stretching of the graft, the current biomechanical study recommends tensioning an anatomic ACL reconstruction at its point of maximal excursion, or between 0 and 5 degrees of flexion. The level of evidence is IV.

Stress Radiography Is a Reliable Method to Quantify Posterior Cruciate Ligament Insufficiency: A Systematic Review.

Purpose: To perform a systematic review of posterior tibial stress radiography techniques and radiographic measurement methods to compare their accuracy and efficacy to aid clinicians in quantifying posterior cruciate ligament laxity. Methods: Electronic databases, including PubMed, MEDLINE, Embase.com 1947- , Ovid Medline 1946- , Scopus 1823- , Cochrane Central Register of Controlled Trials (CENTRAL), and Clinicaltrials.gov 1997- were queried in December 2020. The abstracts of articles were reviewed by 2 authors for published studies comparing posterior tibial stress radiography techniques, describing, and comparing radiographic measurement methods, and comparing stress radiographs with instrumented knee testing. Results: The systematic review included 13 studies that satisfied the inclusion and exclusion criteria. There were 3 studies comparing stress radiography with instrumented knee devices, 6 studies comparing stress radiography techniques, and 5 studies evaluating the reliability of radiographic measurements. Stress radiography was more sensitive for detecting posterior tibial translation than KT-1000 and KT-2000 and was similar to the Rolimeter knee arthrometer. The majority of studies found TELOS stress radiography to be more sensitive than gravity or hamstring contraction stress views. Kneeling stress radiographs were found to be equivalent to TELOS in one study and superior in another. All reported methods of radiographic measurement for posterior tibial translation showed good-to-excellent intraobserver and interobserver reliability, and no single technique demonstrated clear superiority. Conclusions: The results of this systematic review indicate that posterior stress radiography with TELOS and kneeling stress radiography are the most reliable methods to evaluate posterior cruciate ligament laxity. Gravity stress and hamstring contraction can be used but may underestimate posterior tibial translation. Radiographic measurement methods are reliable and no single method is clearly superior. Clinical Relevance: This information will allow clinicians to use various radiographic methods to objectively measure posterior tibial translation to formulate a treatment plan.

Global Variation in Studies of Articular Cartilage Procedures of the Knee: A Systematic Review.

OBJECTIVE: The objective of this study was to determine whether there are significant differences in terms of indications, techniques, patient variables, and objective and subjective outcome scores as a function of the geographic locale of published studies of knee articular cartilage surgery. METHODS: An electronic database search was performed of clinical studies evaluating knee articular cartilage procedures from 2000 to 2021. Studies were separated into global regions (Europe, Asia, North America, and South America) based on the study country. All cartilage-based treatments in each region were recorded. Patient age and sex, mechanism of injury, cartilage lesion size and location, follow-up time, failure rate, and knee outcome scores utilized were summarized and compared by region. RESULTS: A total of 2,923 studies were analyzed. Eighty level 1 and 2 studies met the inclusion criteria. The majority were from Europe (n = 60), followed by Asia (n = 11), North America (n = 7), and South America (n = 2). The majority of procedures in European and North American studies were cell-based and marrow-stimulation procedures. In Asian studies, the most common procedures were marrow-stimulation, experimental, and biologic procedures as defined by the authors. Asian countries had a higher proportion of females (P < 0.001) and an overall older patient population (P < 0.001). Regional variation was also seen in terms of lesion location, mechanism of injury, and failure rate. CONCLUSION: Most high-level evidence for articular cartilage-based procedures of the knee comes from European countries. These studies vary by patient age and sex, anatomic location, and mechanism of injury. Global variation should be taken into consideration when interpreting and applying studies of knee articular cartilage surgery.

Return to play following nonsurgical management of superior labrum anterior-posterior tears: a systematic review.

BACKGROUND: Superior labrum anterior-posterior (SLAP) tears are common shoulder injuries, especially in overhead athletes. Often, initial management of these injuries is nonsurgical with focused rehabilitation. The purpose of this review was to evaluate the outcomes of nonsurgical management of SLAP tears in athletes. METHODS: A systematic review was performed for articles published before March 2021 using key search terms pertaining to clinical studies evaluating the nonsurgical treatment of SLAP tears in adult patients published in English-language literature. Abstracts and manuscripts were independently reviewed by 2 co-authors to determine eligibility. Return-to-play rate and return-to-prior-athletic-performance rate were determined by combining results across studies. RESULTS: Five articles met the inclusion criteria. There were 244 total athletes (162 elite or higher-level athletes). The mean ages ranged from 20.3 to 38.0 years. Type II SLAP tears were most common; baseball, softball, and weightlifting were the most common sports involved. The return-to-play rate was 53.7% in all athletes and 52.5% in elite or higher-level athletes. In athletes who were able to complete their nonoperative rehabilitation program, the return-to-play rate was 78% in all athletes and 76.6% in elite or higher-level athletes. The overall rate of return to prior performance was 42.6%, which increased to 72% for those athletes who were able to complete their rehabilitation. Patients who discontinued the rehabilitation protocol in favor of surgery had an average of 8 physical therapy sessions compared with 20 sessions for patients with successful nonoperative treatment. The timing of return to play was generally less than 6 months in studies that reported it. Patient-reported outcomes, including the American Shoulder and Elbow Surgeons score and visual analog scale, all improved significantly after nonsurgical treatment. Factors associated with failure of nonsurgical management included older age, participation in overhead sports (especially baseball pitchers), traumatic injury, positive compression rotation test, concomitant rotator cuff injury, longer baseball career, longer symptomatic period, and the presence of a Bennett spur. CONCLUSIONS: Overall, nonoperative treatment of SLAP tears in athletes can be successful, especially in the subset of patients who are able to complete their rehabilitation program before attempting a return to play. Although nonoperative treatment should be considered the first line of treatment for most SLAP tears, there are some factors that may be associated with failure of conservative treatment; therefore, further high level, prospective studies would be beneficial to identify those athletes most likely to respond favorably to nonoperative treatment.

The Loop 'N' Tack Biceps Tenodesis: An All-Arthroscopic, Intra-Articular Technique.

Tenodesis and tenotomy of the long head of the biceps are treatment options for a wide range of pathologies without clear superior technique or site of fixation. Clinical outcomes comparing numerous techniques for tenotomy versus tenodesis have resulted in similar pain relief; however, tenotomy may result in a cosmetic "Popeye" deformity and fatigue pain. We present a quick, simple, and knotless technique for tenodesis of the long head of the biceps at the proximal aspect of the bicipital grove that can be completed entirely arthroscopically. This technique uses suture to secure a tenotomized proximal biceps tendon to a knotless anchor just proximal to the subscapularis tendon at the proximal biceps groove. The tensionless repair allows the biceps to scar within the biceps groove, thereby reducing subsidence and formation of a "Popeye" deformity and fatigue pain in the biceps seen with tenotomy alone while eliminating the ability to overtension.

The Loop 'n' Tack Knot: Biomechanical Analysis of a Novel Suture Technique for Proximal Biceps Tenodesis.

BACKGROUND: Secure tendon grasping is critical to the success of any tenodesis procedure. Several techniques currently used for tendon grasping can result in longitudinal splitting of the tendon, causing construct failure and failure of the tenodesis. PURPOSE: To compare the Loop 'n' Tack knot as a tendon-grasping technique with other common suture techniques. We investigated the biomechanical strength and mode of failure. STUDY DESIGN: Controlled laboratory study. METHODS: Eleven matched pairs of proximal biceps were harvested from fresh-frozen cadaveric shoulders. One tendon from each pair was stitched using 1 of 4 different techniques. The suture techniques evaluated included the Loop 'n' Tack with 2 different types of high-strength nonabsorbable suture, a double half-racking stitch, and a Krakow stitch. Samples were cyclically loaded between 5 and 20 N for 100 cycles, followed by a pull to failure at 33 mm/s. RESULTS: The Loop 'n' Tack techniques were equivalent to the double half-racking and Krakow techniques for load to ultimate failure (P = .817 and P = .984, respectively). The double half-racking technique was the stiffest construct, which was significantly greater than the second-stiffest group, the Loop 'n' Tack method with both FiberLink suture (P = .012) and SutureTape (P = .002), which had greater stiffness than the Krakow group (P < .001). The most common failure mode for the Loop 'n' Tack stitch was suture breakage compared with the Krakow and double half-racking methods, where the most common mode of failure was suture pullout from the tendon (P < .001). CONCLUSION: Biomechanical testing found that the Loop 'n' Tack techniques had similar ultimate load to failure values when compared with the double half-racking and Krakow methods. Mode-of-failure analysis showed that the Loop 'n' Tack construct typically failed by suture breakage, whereas the other techniques failed by suture pullout. CLINICAL RELEVANCE: The Loop 'n' Tack technique allows for secure grasping of tissue without the need for externalization of the tendon. This technique may be beneficial in compromised or poor-quality tissue without reducing overall pullout strength when compared with a standard half-racking or Krakow stitch.

Biomechanical Response to Distraction of Hip Capsular Reconstruction With Human Acellular Dermal Patch Graft.

PURPOSE: To quantify the biomechanical properties of the hip capsule with human dermal allograft reconstruction to determine whether a dermal patch restored capsular resistance to distraction. METHODS: Nine cadaveric hip specimens were dissected until capsule and bony structures remained and were then mounted in a testing fixture in neutral flexion and abduction. Four states of the hip capsule were sequentially tested under axial distraction of 5 mm measured with video analysis and with resultant force measurement: (1) intact hip capsule, (2) interportal capsulotomy, (3) capsulectomy to the zona orbicularis, and (4) capsular reconstruction with human dermal allograft using acetabular anchors and capsule-to-patch sutures. RESULTS: Capsulectomy was different from intact (P = .036), capsulotomy differed from capsulectomy (P = .012), and the repair was statistically significantly different from capsulectomy (P = .042); intact and reconstructed cases were not statistically significantly different. The force required for 5 mm of distraction decreased after interportal capsulotomy by an average of 9% compared with the intact state and further decreased after capsulectomy by 30% compared with the intact state. After capsular reconstruction using dermal allograft, force requirements increased by an average of 36% from the capsulectomy state, only 5% below the intact state. CONCLUSIONS: Human dermal allograft tissue graft provides restoration of distractive strength for use during hip capsule reconstruction with acetabular anchor fixation and distal soft-tissue fixation after capsulectomy in a cadaveric model. CLINICAL RELEVANCE: Capsular repair or reconstruction with a dermal patch offers time-zero restoration of function; intact and reconstructed cases showed no difference, and reconstruction restored a capsulectomy to a biomechanical equivalent of the intact case when distraction was applied.

Intracortical remodeling parameters are associated with measures of bone robustness.

Prior work identified a novel association between bone robustness and porosity, which may be part of a broader interaction whereby the skeletal system compensates for the natural variation in robustness (bone width relative to length) by modulating tissue-level mechanical properties to increase stiffness of slender bones and to reduce mass of robust bones. To further understand this association, we tested the hypothesis that the relationship between robustness and porosity is mediated through intracortical, BMU-based (basic multicellular unit) remodeling. We quantified cortical porosity, mineralization, and histomorphometry at two sites (38% and 66% of the length) in human cadaveric tibiae. We found significant correlations between robustness and several histomorphometric variables (e.g., % secondary tissue [R(2) = 0.68, P < 0.004], total osteon area [R(2) = 0.42, P < 0.04]) at the 66% site. Although these associations were weaker at the 38% site, significant correlations between histological variables were identified between the two sites indicating that both respond to the same global effects and demonstrate a similar character at the whole bone level. Thus, robust bones tended to have larger and more numerous osteons with less infilling, resulting in bigger pores and more secondary bone area. These results suggest that local regulation of BMU-based remodeling may be further modulated by a global signal associated with robustness, such that remodeling is suppressed in slender bones but not in robust bones. Elucidating this mechanism further is crucial for better understanding the complex adaptive nature of the skeleton, and how interindividual variation in remodeling differentially impacts skeletal aging and an individuals' potential response to prophylactic treatments.