Complications in Anterior Cruciate Ligament Surgery and How to Avoid Them.

Complications following anterior cruciate ligament (ACL) reconstruction can be detrimental to a patient's recovery and limit their ability to successfully return to sport. Arthrofibrosis, graft failure, and infection are a few examples of complications that can arise. Therefore, it is important for surgeons to recognize that each step during perioperative surgical decision making can impact patients' risk for such complications. The purpose of this paper is to discuss common complications following ACL reconstruction and how surgeons can avoid or reduce the risk of complications.

Margin convergence vs. superior capsular reconstruction for massive irreparable rotator cuff tears: outcomes are equivalent unless there is preoperative pseudoparesis.

BACKGROUND: Margin convergence (MC) and superior capsular reconstruction (SCR) are common treatment options for irreparable rotator cuff tears in younger patients, although they differ in associated costs and operative times. The purpose of this study was to compare range of motion, patient-reported outcomes (PROs), and reoperation rates following MC and SCR. We hypothesized superior outcomes after SCR relative to MC regarding functional outcomes, subjective measures, and reoperation rates. METHODS: This was a multicenter retrospective review of 59 patients from 3 surgeons treating irreparable rotator cuff tears with either MC (n = 28) or SCR (n = 31) and minimum 1-year follow-up from 2014-2019. Visual analog scale (VAS) for pain, Subjective Shoulder Value (SSV), active forward flexion (FF), external rotation (ER), retear rate, and conversion rate to reverse shoulder arthroplasty were evaluated. t tests and χ2 tests were used for continuous and categorical variables, respectively (P < .05). RESULTS: Baseline demographics, range of motion, and magnetic resonance imaging findings were similar between groups. Average follow-up was 31.5 months and 17.8 months for the MC and SCR groups, respectively (P < .001). The MC and SCR groups had similar postoperative FF (151° ± 26° vs. 142° ± 38°; P = .325) and ER (48° ± 12° vs. 46° ± 11°; P = .284), with both groups not improving significantly from their preoperative baselines. However, both cohorts demonstrated significant improvements in VAS score (MC: 7.3 to 2.5; SCR: 6.4 to 1.0) and SSV (MC: 54% to 82%; SCR: 38% to 87%). There were no significant differences in postoperative VAS scores, SSV, and rates of retear or rates of conversion to arthroplasty between the MC and SCR groups. In patients with preoperative pseudoparesis (FF < 90°), SCR (n = 9) resulted in greater postoperative FF than MC (n = 5) (141° ± 38° vs. 67° ± 24°; P = .002). CONCLUSION: Both MC and SCR demonstrated excellent postoperative outcomes in the setting of massive irreparable rotator cuff tear, with significant improvements in PROs and no significant differences in range of motion. Specifically for patients with preoperative pseudoparesis, SCR was more effective in restoring forward elevation. Further long-term studies are needed to compare outcomes and establish appropriate indications.

Current trends in graft choice for anterior cruciate ligament reconstruction - part I: anatomy, biomechanics, graft incorporation and fixation.

Graft selection in anterior cruciate ligament (ACL) reconstruction is critical, as it remains one of the most easily adjustable factors affecting graft rupture and reoperation rates. Commonly used autografts, including hamstring tendon, quadriceps tendon and bone-patellar-tendon-bone, are reported to be biomechanically equivalent or superior compared to the native ACL. Despite this, such grafts are unable to perfectly replicate the complex anatomical and histological characteristics of the native ACL. While there remains inconclusive evidence as to the superiority of one autograft in terms of graft incorporation and maturity, allografts appear to demonstrate slower incorporation and maturity compared to autografts. Graft fixation also affects graft properties and subsequent outcomes, with each technique having unique advantages and disadvantages that should be carefully considered during graft selection.

Current trends in graft choice for primary anterior cruciate ligament reconstruction - part II: In-vivo kinematics, patient reported outcomes, re-rupture rates, strength recovery, return to sports and complications.

Postoperative patient satisfaction after anterior cruciate ligament reconstruction (ACL-R) is influenced mainly by the degree of pain, the need for reoperation, and functional performance in daily activities and sports. Graft choice has shown to have an influence on postoperative outcomes after ACL-R. While patient reported outcomes measurements do not differ between graft options, evidence shows that normal knee kinematics is not fully restored after ACL-R with an increase in postoperative anterior tibial translation (ATT). Postoperative graft rupture rates seem to favor bone-patella-tendon-bone (BPTB) and quadriceps tendon (QT) autografts over HT or allografts. While return to sports rates seem comparable between different graft types, postoperative extensor strength is reduced in patients with BPTB and QT whereas flexion strength is weakened in patients with HT. Postoperative donor site morbidity is highest in BPTB but comparable between HT and QT. With all graft options having advantages and drawbacks, graft choice must be individualized and chosen in accordance with the patient.

Knotted and knotless double row transosseous equivalent repair techniques for arthroscopic rotator cuff repair demonstrate comparable post-operative outcomes.

PURPOSE: To compare failure rates and outcomes after transosseous equivalent (TOE) double row (DR) knotted suture bridge versus knotless suture tape bridge repair techniques for rotator cuff tears. METHODS: A consecutive series of 272 shoulders in 256 patients who underwent arthroscopic, double row, TOE repair for full-thickness tears of the supraspinatus tendon were reviewed. Eighty-four shoulders were repaired using knotted suture bridge (KSB) technique, and 188 shoulders were repaired using all knotless suture tape bridge (KTB) technique. Revision procedures and concomitant subscapularis tendon repairs were excluded from analysis. The minimum follow-up was 12 months. Primary outcome was failure of surgical repair, defined as either confirmed retear on MRI and/or need for revision surgery. Secondary clinical outcome measures were assessed including range of motion, strength, visual analog scale (VAS), operative time, subjective shoulder value (SSV), Patient-Reported Outcomes Measurement Information System (PROMIS) mental and physical health, American Shoulder and Elbow Surgeons Shoulder Score (ASES), Brophy shoulder activity scores, and need for manipulation under anesthesia (MUA). RESULTS: A total of 127 shoulders (38 KSB and 89 KTB) met inclusion criteria for the study. No significant difference in demographic variables were present between the groups at baseline. Supraspinatus tear size and average follow-up time did not differ significantly between groups. Failure rates were similar between the KSB and KTB repairs (13.1 vs 7.9%, n.s.). There was no significant difference in functional outcomes including strength, range of motion in forward flexion and external rotation, as well as patient reported outcomes including VAS, SSV, PROMIS, ASES, and Brophy scores between the groups. There was also no difference in post-operative stiffness requiring MUA. CONCLUSION: Both KSB and KTB repair techniques demonstrate low retear rates with excellent functional outcomes when compared to pre-operative examination. Both KSB and KTB techniques are viable options for achieving a successful rotator cuff repair. LEVEL OF EVIDENCE: Level III.

Increasing the posterior tibial slope lowers in situ forces in the native ACL primarily at deep flexion angles.

High tibial osteotomy is becoming increasingly popular but can be associated with unintentional posterior tibial slope (PTS) increase and subsequent anterior cruciate ligament (ACL) degeneration. This study quantified the effect of increasing PTS on knee kinematics and in situ forces in the native ACL. A robotic testing system was used to apply external loads from full extension to 90° flexion to seven human cadaveric knees: (1) 200 N axial compressive load, (2) 5 Nm internal tibial + 10 Nm valgus torque, and (3) 5 Nm external tibial + 10 Nm varus torque. Kinematics and in situ forces in the ACL were acquired for the native and increased PTS state. Increasing PTS resulted in increased anterior tibial translation at 30° (1.8 mm), 60° (1.7 mm), and 90° (0.9 mm) flexion and reduced in situ force in the ACL at 30° (57.6%), 60° (69.8%), and 90° (75.0%) flexion in response to 200 N axial compressive load. In response to 5 Nm internal tibial + 10 Nm valgus torque, there was significantly less (39.0%) in situ force in the ACL at 90° flexion in the increased compared with the native PTS state. Significantly less in situ force in the ACL at 60° (62.8%) and 90° (67.0%) flexion was observed in the increased compared with the native PTS state in response to 5 Nm external tibial + 10 Nm varus torque. Increasing PTS affects knee kinematics and results in a reduction of in situ forces in the native ACL during compressive and rotatory loads at flexion angles exceeding 30°. In a controlled laboratory setting PTS increase unloads the ACL, affecting its natural function.

High-grade preoperative osteoarthritis of the index compartment is a major predictor of meniscal allograft failure.

INTRODUCTION: Preoperatively available predictors of meniscal allograft failure would help in patient counseling and surgical indication for meniscal allograft transplantation (MAT). It was hypothesized that young patient age, high posterior tibial slope (PTS), and high-grade osteoarthritis (OA) are predictors of meniscal allograft failure. MATERIALS AND METHODS: Patients undergoing MAT with a minimum follow-up of 2 years were included in this retrospective study. Demographic and surgical data, and causes of meniscal allograft failure were collected. PTS and degree of OA (low-grade: Kellgren-Lawrence 0, 1, and 2; high-grade: Kellgren-Lawrence 3 and 4) of the index and opposite tibiofemoral compartments were determined on preoperative radiographs. RESULTS: This study included 77 patients with a mean age of 25.7 ± 10.1 years at the time of MAT. After a mean follow-up of 7.6 ± 5.6 years, meniscal allograft failure was observed in 26 patients (34%). The median time from MAT to meniscal allograft failure was 1.3 years (inter-quartile range, 2.5 years). Meniscal allograft tears (88%) were the primary cause of graft failure, followed by high-grade OA (12%). Patients experiencing meniscal allograft failure were an average of 2.7 years (95% CI [2.2, 7.5], p = 0.202) older at the time of MAT than patients without failure. PTS was not found to be a predictor of meniscal allograft failure (odds ratio, 0.884 (95% CI [0.727, 1.073], p = 0.212)). Patients with high-grade preoperative OA of the index compartment had 28 times higher odds of experiencing meniscal allograft failure than patients with low-grade preoperative OA (p = 0.008). CONCLUSIONS: High-grade preoperative OA of the index compartment was found to be a significant and clinically relevant predictor of meniscal allograft failure. Surgeons should be aware of the impact of OA on meniscal allograft survival, which needs to be considered in patient counseling and surgical indication for MAT in patients.

Bone loss in shoulder instability: putting it all together.

Glenohumeral bone loss is frequently observed in cases of recurrent anterior and posterior shoulder instability and represents a risk factor for failure of nonoperative treatment. Patients with suspected glenoid or humeral bone loss in the setting of recurrent instability should be evaluated with a thorough history and physical examination, as well as advanced imaging including computed tomography (CT) and/or magnetic resonance imaging (MRI). In cases of both anterior and posterior instability, the magnitude and location of bone loss should be determined, as well as the relationship between the glenoid track (GT) and any humeral defects. While the degree and pattern of osseous deficiency help guide treatment, patient-specific risk factors for recurrent instability must also be considered when determining patient management. Treatment options for subcritical anterior bone loss include labral repair and capsular plication, while more severe deficiency should prompt consideration of bony augmentation including coracoid transfer or free bone block procedures. Concomitant humeral lesions are treated according to the degree of engagement with the glenoid rim and may be addressed with soft tissue remplissage or bony augmentation procedures. While critical and subcritical thresholds of glenoid bone loss guide the management of anterior instability, such thresholds are less defined in the setting of posterior instability. Furthermore, current treatment algorithms are limited by a lack of long-term comparative studies. Future high-quality studies as well as possible modifications in indications and surgical technique are required to elucidate the optimal treatment of anterior, posterior, and bipolar glenohumeral bone loss in the setting of recurrent shoulder instability.

Player Position and Labral Tear Location and Size in NCAA Division I Football Players Undergoing Arthroscopic Surgery.

Background: Shoulder instability attributed to glenoid labral tears is common among National Collegiate Athletic Association (NCAA) football players. Certain repetitive activities by player position may contribute to instability. Purpose: To compare the location of labral tears among player positions in NCAA Division I football. Study Design: Cross-sectional study. Methods: We conducted a review of football players who underwent shoulder labral repair between 2000 and 2020 at a single institution. Inclusion criteria were NCAA Division I level, diagnosis of shoulder instability, and labral tear requiring arthroscopic repair. Exclusion criteria were prior surgery on injured shoulder and incomplete medical records. Players were divided into 3 groups: line players (offensive and defensive linemen, defensive end), skill players (defensive back, wide receiver, running back, and quarterback), and hybrid players (linebacker and tight end). Labral tear location and size were recorded using the clockface method and categorized into 6 zones: superior, anterosuperior, anteroinferior, inferior, posteroinferior, and posterosuperior. Comparison of variables was performed using chi-square test or Fisher exact test (categorical) and 1-way analysis of variance or Kruskal-Wallis H test (continuous). The Spearman rank-order correlation was used to assess relationships between continuous data. Results: Of the 53 included players, 37 (70%) were offensive linemen, defensive linemen, and linebackers. There were 29 line players, 11 skill players, and 13 hybrid players. Line players represented 55% of included players and had the most total labral tears as compared with all groups. Hybrid players had a significantly higher percentage of posterosuperior tears than line players (92% vs 52%; P = .015) and skill players (92% vs 27%; P = .002). Skill players had a significantly higher percentage of anterior tears at 3:00-4:00 and 5:00-6:00 when compared with hybrid players (82% vs 15%, P = .003; 82% vs 31%, P = .012, respectively). There was a positive correlation between labral tear size and number of suture anchors (0; P = .010). Conclusion: In this study of NCAA Division I football players, skill players had a higher proportion of anteroinferior labral tears, and hybrid players had a higher proportion of posterosuperior labral tears.

Freddie Fu: A Leader of Leaders.

Freddie Fu had a profound and undeniable impact on the field of orthopaedic surgery. He was a leader both personally and professionally and dedicated his career to ensuring that those around him had the opportunity to thrive. His life and career were distinguished by his exceptional leadership, boundless collaboration, and dedication to diversity. Freddie Fu's ability to train future leaders represents one of his greatest professional legacies, which will continue to permeate the field of orthopaedic surgery for decades to come. He was a giant, and those fortunate enough to train under him are better because of it.

Low posterior tibial slope is associated with increased risk of PCL graft failure.

PURPOSE: To evaluate the effect of posterior tibial slope (PTS) on patient-reported outcomes (PROs) and posterior cruciate ligament (PCL) graft failure after PCL reconstruction. METHODS: Patients undergoing PCL reconstruction with a minimum 2-year follow-up were included in this retrospective cohort study. A chart review was performed to collect patient-, injury-, and surgery-related data. Medial PTS was measured on preoperative lateral radiographs. Validated PROs, including the International Knee Documentation Committee Subjective Knee Form, Knee injury and Osteoarthritis Outcome Score, Lysholm Score, Tegner Activity Scale, and Visual Analogue Scale for pain, were collected at final follow-up. A correlation analysis was conducted to assess the relationship between PTS and PROs. A logistic regression model was performed to evaluate if PTS could predict PCL graft failure. RESULTS: Overall, 79 patients with a mean age of 28.6 ± 11.7 years and a mean follow-up of 5.7 ± 3.3 years were included. After a median time from injury of 4.0 months, isolated and combined PCL reconstruction was performed in 22 (28%) and 57 (72%) patients, respectively. There were no statistically significant differences in PROs and PTS between patients undergoing isolated and combined PCL reconstruction (non-significant [n.s.]). There were no significant correlations between PTS and PROs (n.s.). In total, 14 (18%) patients experienced PCL graft failure after a median time of 17.5 months following PCL reconstruction. Patients with PCL graft failure were found to have statistically significantly lower PTS than patients without graft failure (7.0 ± 2.3° vs. 9.2 ± 3.3°, p < 0.05), while no differences were found in PROs (n.s.). PTS was shown to be a significant predictor of PCL graft failure, with a 1.3-fold increase in the odds of graft failure for each one-degree reduction in PTS (p < 0.05). CONCLUSIONS: This study showed that PTS does not affect PROs after PCL reconstruction, but that PTS represents a surgically modifiable predictor of PCL graft failure. LEVEL OF EVIDENCE: III.

A high tibial slope, allograft use, and poor patient-reported outcome scores are associated with multiple ACL graft failures.

PURPOSE: To compare clinical outcomes, radiographic characteristics, and surgical factors between patients with single and multiple anterior cruciate ligament (ACL) graft failures. It was hypothesized that patients experiencing multiple ACL graft failures exhibit lower patient-reported outcome scores (PROs) and a higher (steeper) posterior tibial slope (PTS) than patients with single ACL graft failure. METHODS: Patients undergoing revision ACL reconstruction with a minimum follow-up of 12 months were included in this retrospective cohort study. Based on the number of ACL graft failures, patients were assigned either to the group "single ACL graft failure "or" multiple ACL graft failures ". The PTS was measured on strict lateral radiographs. Validated PROs including the International Knee Documentation Committee (IKDC) subjective knee form, Knee Injury and Osteoarthritis Outcome Score, Lysholm Score, Tegner Activity Scale, ACL-Return to Sport after Injury Scale, and Visual Analogue Scale for pain were collected. RESULTS: Overall, 102 patients were included with 58 patients assigned to the single ACL graft failure group and 44 patients to the multiple ACL graft failures group. Quadriceps tendon autograft was used significantly more often (55% vs. 11%, p < 0.001) and allografts were used significantly less often (31% vs. 66%, p < 0.001) as the graft for first revision ACL reconstruction in patients with single versus multiple ACL graft failures. Patients with multiple ACL graft failures were associated with statistically significantly worse PROs (IKDC: 61.7 ± 19.3 vs. 77.4 ± 16.8, p < 0.05; Tegner Activity Scale: 4 (range, 0-7) vs. 6 (range 2-10), p < 0.05), higher PTS (12 ± 3° vs. 9 ± 3°, p < 0.001), and higher rates of subsequent surgery (73% vs. 14%, p < 0.001) and complications (45% vs. 17%, p < 0.05) than patients with single ACL graft failure. CONCLUSION: Compared to single ACL graft failure in this study multiple ACL graft failures were associated with worse PROs, higher PTS, and allograft use. During the first revision ACL reconstruction, it is recommended to avoid the use of allografts and to consider slope-reducing osteotomies to avoid multiple ACL graft failures and improve PROs. LEVEL OF EVIDENCE: Level 3.

Editorial Commentary: The Importance of Bony Morphology in the Anterior Cruciate Ligament-Injured Patient.

The outcome of anterior cruciate ligament (ACL) surgery depends on many factors. Successful ACL surgery includes evaluating patients' characteristics and addressing all the underlying knee pathologies, including the meniscus tears and ramp lesions. In recent years, there has been a growing interest in ramp lesions as well as the role that bony morphology plays in predisposing patients to ACL injury and failed ACL surgery. Not only pathologic but also physiologic variations in bony morphology like tibial slope and lateral femoral condyle ratio have been correlated with clinical outcomes, failure rates, rotatory instability, and even lesions to the contralateral knee. Evaluating each patient's specific anatomy is recommended when customizing ACL surgery. With further research and increased awareness of relevant bony parameters, we will be able to improve our ability to prevent injury, increase the diagnostic accuracy of associated lesions, and tailor surgery to improve the outcomes and reduce failure rates.

Association Between Meniscal Allograft Tears and Early Surgical Meniscal Allograft Failure.

BACKGROUND: Meniscal allograft transplantation (MAT) has become a viable treatment option for patients with symptomatic meniscal deficiency. Some patients experience early surgical meniscal allograft failure attributed to causes that have not yet been sufficiently clarified. PURPOSE: To evaluate the prevalence, types, and distribution of arthroscopically confirmed meniscal allograft tears and the associated effect on surgical meniscal allograft survival. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Patients undergoing MAT with a minimum 2-year follow-up were retrospectively reviewed. Descriptive and surgical data were collected. Type and location of arthroscopically confirmed meniscal allograft tears were recorded and compared between medial and lateral allografts and suture-only and bone block fixation. A survival analysis was conducted to evaluate the effect of meniscal allograft tears on surgical meniscal allograft survival. RESULTS: This study included 142 patients (54% male; mean ± SD age, 29.6 ± 10.4 years) with a mean follow-up of 10.3 ± 7.5 years. The prevalence of meniscal allograft tears was 32%, observed at a median of 1.2 years (interquartile range, 2.8 years) after MAT. The posterior horns were most frequently affected, followed by the posterior roots, midbodies, anterior horns, and anterior roots. The most frequently observed tear types were root tears (43%), followed by longitudinal, horizontal, radial, complex, bucket-handle, and meniscocapsular separation tears. A statistically significant association was found between meniscal allograft tear types and fixation techniques (P = .027), with root tears predominant after suture-only as compared with bone block fixation (57% vs 22%). Patients with meniscal allograft root tears were a mean of 5.4 years (95% CI, 1.6-9.2 years; P = .007) younger than were patients without root tears. The 1-year surgical meniscal allograft survival rate was significantly lower for torn versus intact meniscal allografts (75% vs 99%; P < .001). CONCLUSION: Meniscal allograft root tears were predominant, associated with younger patient age, and more often observed when using the suture-only fixation technique versus the bone block fixation technique. Torn meniscal allografts were associated with early surgical graft failure when compared with intact meniscal allografts, resulting in a significantly lower 1-year survival rate.

Operative time in adolescent idiopathic scoliosis surgery: a need for a standard definition.

Our objective is to report and define 'operative time' in adolescent idiopathic scoliosis (AIS) posterior spinal fusion surgeries. Documenting key times during surgery are important to compare operative risks, assess learning curves, and evaluate team efficiency in AIS surgery. 'Operative time' in literature has not been standardized. Systematic review was performed by two reviewers. Keywords included operative time, duration of surgery, and scoliosis. One thousand nine hundred six studies were identified, 1092 duplicates were removed and 670 abstracts were excluded. Of the 144 articles, 67 met inclusion and exclusion criteria. Studies were evaluated for number of patients, operative time, and definition of operative time. Meta-analysis was not performed due to confounders. Of the 67 studies (6678 patients), only 14 (1565 patients) defined operative time, and all specified as incision to closure. From these 14 studies, the median operative time was 248 minutes (range 174-448 minutes). In the 53 studies (5113 patients) without a definition, one study reported time in a non-comparable format, therefore, data were analyzed for 52 studies (5078 patients) with a median operative time of 252 minutes (wider range 139-523 minutes). A clear standardized definition of operative or surgical time in spine surgery does not exist. We believe that operative time should be clearly described for each published study for accurate documentation and be defined from incision time to spine dressing completion time in order to standardize study results. Level of evidence: IV.

Evolving evidence in the treatment of primary and recurrent posterior cruciate ligament injuries, part 1: anatomy, biomechanics and diagnostics.

The posterior cruciate ligament (PCL) represents an intra-articular structure composed of two distinct bundles. Considering the anterior and posterior meniscofemoral ligaments, a total of four ligamentous fibre bundles of the posterior knee complex act synergistically to restrain posterior and rotatory tibial loads. Injury mechanisms associated with high-energy trauma and accompanying injury patterns may complicate the diagnostic evaluation and accuracy. Therefore, a thorough and systematic diagnostic workup is necessary to assess the severity of the PCL injury and to initiate an appropriate treatment approach. Since structural damage to the PCL occurs in more than one third of trauma patients experiencing acute knee injury with hemarthrosis, background knowledge for management of PCL injuries is important. In Part 1 of the evidence-based update on management of primary and recurrent PCL injuries, the anatomical, biomechanical, and diagnostic principles are presented. This paper aims to convey the anatomical and biomechanical knowledge needed for accurate diagnosis to facilitate subsequent decision-making in the treatment of PCL injuries.Level of evidence V.

Evolving evidence in the treatment of primary and recurrent posterior cruciate ligament injuries, part 2: surgical techniques, outcomes and rehabilitation.

Isolated and combined posterior cruciate ligament (PCL) injuries are associated with severe limitations in daily, professional, and sports activities as well as with devastating long-term effects for the knee joint. As the number of primary and recurrent PCL injuries increases, so does the body of literature, with high-quality evidence evolving in recent years. However, the debate about the ideal treatment approach such as; operative vs. non-operative; single-bundle vs. double-bundle reconstruction; transtibial vs. tibial inlay technique, continues. Ultimately, the goal in the treatment of PCL injuries is restoring native knee kinematics and preventing residual posterior and combined rotatory knee laxity through an individualized approach. Certain demographic, anatomical, and surgical risk factors for failures in operative treatment have been identified. Failures after PCL reconstruction are increasing, confronting the treating surgeon with challenges including the need for revision PCL reconstruction. Part 2 of the evidence-based update on the management of primary and recurrent PCL injuries will summarize the outcomes of operative and non-operative treatment including indications, surgical techniques, complications, and risk factors for recurrent PCL deficiency. This paper aims to support surgeons in decision-making for the treatment of PCL injuries by systematically evaluating underlying risk factors, thus preventing postoperative complications and recurrent knee laxity. LEVEL OF EVIDENCE: V.