Graft failure is a common postoperative complication after anterior cruciate ligament (ACL) reconstruction. Recently, a theory has emerged that histological and microstructural factors of autografts may be related to graft failure. We simultaneously collected the semitendinosus tendon (ST), quadriceps tendon (QT), and patellar tendon (PT) from a 22-year-old patient to provide insights into the differences in the collagen-type composition of the three tendons in skeletally mature patients. These findings may serve as a basis for selecting autografts for ACL to reduce graft failure rates. The patient was a 22-year-old female who required the removal of artificial ligament, screws, and washers and medial patellofemoral ligament (MPFL) reconstruction with an ST autograft after two surgeries for recurrent dislocation of the left patella. The ST, QT, and PT obtained during necessary intraoperative procedures were used as samples. The tissues were processed and immunostained; this was followed by confocal microscopy. Evaluation was performed by calculating the percentage of areas positive for collagen types I and III.The percentage of type I collagen in the ST, QT, and PT groups was 88%, 85%, and 88%, respectively.The collagen-type composition was examined following simultaneous collection of the ST, QT, and PT. The results revealed no significant differences in the content of physically strong type I collagen, which supports previous findings showing that the clinical outcomes after ACL reconstruction do not vary with the autograft used.

UNASSIGNED: The extensor mechanism and patellar tendon (PT) are considered essential components. Adult PT avulsion from the tibial tubercle is uncommon, with little information in the literature. Technical challenges arise during injury management. Knotless anchors have several applications in treating tendon injuries, such as the rotator cuff, distal biceps, and quadriceps tendons but were not used to repair distal PT avulsions.
UNASSIGNED: A 50-year-old male patient, an active adult, presented to emergency department with significant right knee pain, giving away and limitation of range of motion (ROM) that had started after he sustained direct trauma with a ground-level fall on his knee that morning.
UNASSIGNED: In this paper, we report a case and describe a technique to manage a rare presentation of pure distal PT rupture without an avulsion fracture using knotless anchors with FiberTape®, which showed excellent results. To the best of our knowledge, this technique has never been used before in such injury and anatomical location. At 2 years of follow-up, the patient is free of complaints with almost full ROM at the knee and back to his standard daily life activity.

BACKGROUND: Pain provocation tests are recommended for assessing pain severity and as an outcome measure for individuals with patellar tendinopathy.
OBJECTIVE: To evaluate floor and ceiling effects, sensitivity to change, and responsiveness cut-offs of two provocative load tests among athletes with patellar tendinopathy.
METHODS: Athletes (N = 41) performed six repetitions for the single leg decline squat (SLDS) and resisted knee extension (KE) at baseline and 12 weeks. Participants rated their pain during each test on a visual analog scale (VAS). Sensitivity to change was assessed by calculating effect size (ES) and the standardized response mean (SRM). The responsiveness cut-offs were assessed using a combination of anchor and distribution- based methods to determine the minimal clinically important difference (MCID) for each test.
RESULTS: A floor or ceiling effect was observed in only a small number of participants for both tests except for KE, for which approximately one third of participants had a floor effect at week 12. There was higher sensitivity to change for SLDS (ES: 1.93/SRM: 1.43) compared with KE (ES:0.96/SRM: 1.09). The MCID corresponded to a decrease of 1.6 points for SLDS and 1.0 for KE, while the distribution-based method estimated 1.2 points for SLDS and 1.1 for KE.
CONCLUSIONS: This study found moderate to high sensitivity to change and established MCID values for the SLDS and KE test in athletes with patellar tendinopathy before and after rehabilitation. Both tests may be useful as pain on loading outcomes as athletes progress with their rehabilitation, but the KE test results in higher floor effects and has lower sensitivity to change.

Background: The treatment of patellar tendon injury has always been an unsolved problem, and mechanical characterization is very important for its repair and reconstruction. Elastin is a contributor to mechanics, but it is not clear how it affects the elasticity, viscoelastic properties, and structure of patellar tendon. Methods: The patellar tendons from six fresh adult experimental pigs were used in this study and they were made into 77 samples. The patellar tendon was specifically degraded by elastase, and the regional mechanical response and structural changes were investigated by: (1) Based on the previous study of elastase treatment conditions, the biochemical quantification of collagen, glycosaminoglycan and total protein was carried out; (2) The patellar tendon was divided into the proximal, central, and distal regions, and then the axial tensile test and stress relaxation test were performed before and after phosphate-buffered saline (PBS) or elastase treatment; (3) The dynamic constitutive model was established by the obtained mechanical data; (4) The structural relationship between elastin and collagen fibers was analyzed by two-photon microscopy and histology. Results: There was no statistical difference in mechanics between patellar tendon regions. Compared with those before elastase treatment, the low tensile modulus decreased by 75%-80%, the high tensile modulus decreased by 38%-47%, and the transition strain was prolonged after treatment. For viscoelastic behavior, the stress relaxation increased, the initial slope increased by 55%, the saturation slope increased by 44%, and the transition time increased by 25% after enzyme treatment. Elastin degradation made the collagen fibers of patellar tendon become disordered and looser, and the fiber wavelength increased significantly. Conclusion: The results of this study show that elastin plays an important role in the mechanical properties and fiber structure stability of patellar tendon, which supplements the structure-function relationship information of patellar tendon. The established constitutive model is of great significance to the prediction, repair and replacement of patellar tendon injury. In addition, human patellar tendon has a higher elastin content, so the results of this study can provide supporting information on the natural properties of tendon elastin degradation and guide the development of artificial patellar tendon biomaterials.

暂无摘要。

The aim of this study was to investigate the effect of aging and resistance training with a moderate load on the size and mechanical properties of the patellar (PT) and Achilles tendon (AT) and their associated aponeuroses; medial gastrocnemius (MG) and vastus lateralis (VL). Young (Y55; 24.8 ± 3.8 yrs, n = 11) and old men (O55; 70.0 ± 4.6 yrs, n = 13) were assigned to undergo a training program (12 weeks; 3 times/week) of moderate slow resistance training [55% of one repetition maximum (RM)] of the triceps surae and quadriceps muscles. Tendon dimensions were assessed using 1.5 T magnetic resonance imaging before and after 12 weeks. AT and PT cross sectional area (CSA) were determined every 10% of tendon length. Mechanical properties of the free AT, MG aponeurosis, PT, and VL aponeurosis were assessed using ultrasonography (deformation) and tendon force measurements. CSA of the AT but not PT was greater in O55 compared with Y55. At baseline, mechanical properties were generally lower in O55 than Y55 for AT, MG aponeurosis and VL aponeurosis (Young\'s modulus) but not for PT. CSA of the AT and PT increased equally in both groups following training. Further, for a given force, stiffness and Young\'s modulus also increased equally for VL aponeurosis and AT, for boths groups. The present study highlights that except for the PT, older men have lower tendon (AT, MG aponeurosis, and VL aponeurosis) mechanical properties than young men and 12-weeks of moderate slow resistance training appears sufficient to improve tendon size and mechanical adaptations in both young and older men. New and Noteworthy: These novel findings suggest that short-term moderate slow resistance training induces equal improvements in tendon size and mechanics regardless of age.

The surgical treatment of anterior cruciate ligament (ACL) injuries dates back over 100 years from the present day [2022]. While open repair of the torn ACL was popularized in the early 1900s, the first ACL reconstructions utilized the fascia lata as a graft and other extra-articular stabilizing techniques. The first free tendon graft reported for ACL reconstructions was the quadriceps tendon (QT) in the 1930s, followed by the hamstrings tendon (HT), and then the patellar tendon. With improved understanding of the ACL anatomy and biomechanics and the invention of the arthroscope, ACL reconstruction evolved from open procedures to arthroscopic. Similarly, with the help of many surgeon-scientists who reported patient outcomes following ACL reconstruction with various techniques, graft choice evolved with the hamstrings and patellar tendon grafts becoming the dominant and preferred choice of both surgeons and patients. In present day, we see a resurgence of one of the original grafts reported, the QT, as well as primary ACL repair. Future research will result in continued advancements of ACL surgical techniques and graft harvesting, which will allow the orthopedic community (including patients and surgeons) to benefit from such innovations and advanced technologies.

BACKGROUND: There are two variants regarding the low location of the patella in relation to the tibio-femoral joint line: patella baja (PB) and pseudo-patella baja (PPB). The purpose of this study is to investigate the incidence of PB and PPB in a cohort of patients that underwent revision total knee arthroplasty (rTKA) for aseptic reasons and describe any differences in each group\'s ROM.
METHODS: This retrospective study included 114 patients that underwent aseptic revision TKA surgery between 2017 and 2022. Patients were revised either for stiffness (Group 1) or aseptic loosening/instability (Group 2). The Insall-Salvati ratio (ISR) and Blackburne-Peel ratio (BPR) were used to evaluate the patellar position. ISR < 0.8 defined PB, while cases with ISR ≥ 0.8 and BPI < 0.54 were defined as PPB. ROM was measured and a subanalysis was conducted to investigate the progression of the values of ISR and BPR.
RESULTS: 55 patients comprised Group 1, and 59 patients comprised Group 2. Overall, 13 cases (11.4%) had PB before rTKA and 24 (21%) had PB after rTKA. Cases with PPB were 13 (11.4%) before and 34 (29.9%) after rTKA. Group 1 patients presented with more PB before and after rTKA (12.8% vs 10.2% and 27.3% vs 15.2% respectively). However, after rTKA Group 1 patients presented with less PPB (20%) compared to Group 2 (39%) (p = 0.02). In Group 1, patients with PPB after rTKA had less ROM compared to those without PPB [83.2 (± 21.9) vs 102.1 (± 19.9) (p = 0.025)]. The subanalysis (69 patients) showed a statistically significant decrease in ISR before and after rTKA (p = 0.041), and from the native knee to post-rTKA (p = 0.001). There was a statistically significant decrease in BPR before and after rTKA (p = 0.001) and from the native knee to both pre- and post-rTKA (p < 001).
CONCLUSIONS: After undergoing rTKA, the incidences of both patella baja (PB) and pseudo-patella baja (PPB) increased. Stiffness in the knee was associated with a higher incidence of PB, while non-stiffness cases showed a significantly higher incidence of PPB. Patients with stiff knees and PPB after rTKA experienced a significant reduction in range of motion (ROM). Additionally, the study revealed a noteworthy decrease in ISR and BPR with each subsequent surgery. This information is crucial for healthcare providers, as it sheds light on potential risks and outcomes of rTKA, allowing for improved patient management and surgical decision-making.
METHODS: III.

UNASSIGNED: The aim of the study was to explore if the patellar tendon angles (PTAs) is an intrinsic risk factor for anterior cruciate ligament (ACL) rupture. We hypothesised that the PTAs will be increased in ACL rupture patients compared to matched controls.
UNASSIGNED: We performed a retrospective radiographic cohort study. A cohort of ACL-injured patients between 2019 and 2022 was utilised. The control population, from the same time period, was a consecutive series of 100 patients without ligament or meniscal injuries which were prospectively added to our institutional registry. Posterior tibial slope (PTS), static anterior tibial translation (SATT), patellar tendon to tibial plateau angle (PT-TPA), patellar tendon-tibial shaft angle (PT-TSA) were measured.
UNASSIGNED: A total of 100 patients were included in the control cohort and 110 in the ACL cohort. The PT-TPA was significantly less in the ACL cohort compared to the control cohort, mean and SD of 15.33 (±5.74) versus 13.91 (±5.68), respectively (p = 0.01). PT-TSA was also less in the ACL cohort, mean and SD of 116.15 (±5.89) versus 114.27 (±4.81), however, this failed to reach statistical significance (p = 0.08). The PT-TPA was not correlated with PTS (p = 0.65) and the PT-TSA was inversely correlated with PTS; Pearson correlation coefficient of -0.28 (p < 0.01). The PT-TSA had a greater correlation -0.4 (p < 0.01) with SATT than PTS 0.37 (p < 0.01).
UNASSIGNED: PTAs are not elevated in ACL-injured subjects. While anteriorisation of the tibial tubercle is utilised in dogs to decrease the anterior thrust resulting from the anteriorly directed vector of the quadriceps, this treatment in the humans is not warranted and methods to reduce the PTAs should focus on prehabilitation and rehabilitation.
UNASSIGNED: Level III.

UNASSIGNED: Although extensor mechanism failure following total knee arthroplasty (TKA) is a devastating complication and has been heavily studied in the literature, the impact of extensor mechanism rupture and concomitant repair prior to TKA has not previously been evaluated. The purpose of this investigation was to evaluate how quadriceps and/or patellar tendon repairs prior to TKA would impact medical and surgery-related complications following TKA.
UNASSIGNED: The PearlDiver database was retrospectively reviewed to identify all primary TKA patients from 2010 to 2019. Patients who underwent quadriceps or patellar tendon repair prior to TKA were matched using a propensity score algorithm to a control cohort. We compared medical and surgical complication rates, emergency room visits, readmissions, and 90-day cost of care between the groups.
UNASSIGNED: A total of 1197 patients underwent extensor mechanism repair prior to TKA and were matched to 11,970 patients who did not undergo repair prior to TKA. Patients who underwent extensor mechanism repair had higher rates of 90-day medical complications, as well as 1-year surgery-related complications including revision TKA (odds ratio [OR] 6.06; P < .001), lysis of adhesions (OR 2.18; P = .026), aseptic loosening (OR 2.21; P = .018), infection (OR 7.58; P < .001), and fracture (OR 8.53; P < .001). Patients with prior extensor mechanism repair were more likely to return to the emergency department (OR 1.66; P < .001) and become readmitted (OR 4.15; P < .001) within 90 days.
UNASSIGNED: Patients with previous extensor mechanism repair exhibited higher medical and surgery-related complications, including lysis of adhesions, following TKA than a control cohort. These findings may suggest that patients may require additional surveillance in the early postoperative period to avoid these disastrous complications following primary TKA.