The fate of patellar tendon and infrapatellar fat pad after arthroscopy via central portal

Central Transpatellar Tendon Portal Is Safe When Used for Anterior Cruciate Ligament Reconstruction

Central transpatellar tendon portal (CTP) was suggested first for complex meniscal lesion and subsequently for a better femoral footprint view during reconstruction of anterior cruciate ligament (ACL). A comprehensive evaluation of possible consequences of using the CTP performing an ACL reconstruction does not exist. Our hypothesis was that the use of CTP for ACL reconstruction does not lead to a higher rate of complications or clinically evident radiological abnormalities. In total, 141 patients were prospectively evaluated, 69 underwent ACL reconstruction using a standard high medial portal as view portal, and 72 where a CTP was used. Clinical evaluation, Kujala's score, patellar height, and magnetic resonance (MR) abnormalities were evaluated up to 1-year follow-up. Clinical complications were reported in 16 cases with no statistically significant differences between the two groups. The group 2 had significantly more MR abnormalities (p = 0.048), but the differences in MR alterations do not have any clinical repercussion even in a sports-active population. No differences were found between the groups in Kujala's score, time to return to work, and sport or patellar height. The overall mean preoperative Caton-Deschamps Index decreased significantly (p = 0.034) postoperatively. Postoperative patellar height seems to slightly decrease after ACL reconstruction regardless of the kind of the portals used intraoperatively and the initial patellar height. Nevertheless, this change in patellar height does not influence the postoperative outcome. CTP used for ACL reconstruction does not lead to significative major clinical complications.

Partial resection of the infrapatellar fat pad during anterior cruciate ligament reconstruction has no effect on clinical outcomes including anterior knee pain

BACKGROUND

Anterior knee pain (AKP) is a major complication that occurs after anterior cruciate ligament reconstruction (ACLR), even when hamstring tendon (HT) grafts are used. Damage to the infrapatellar fat pad (IPFP) during arthroscopy can cause AKP. The purpose of this study was to evaluate the influence of IPFP preservation on clinical outcomes, including AKP, in patients who underwent ACLR with HT autografts using the inside-out technique.

METHODS

Forty-two patients who underwent primary ACLR with HT autografts were prospectively assessed for 2 years after surgery. They were randomly selected to undergo treatment with as much intercondylar IPFP preservation as possible or with intercondylar IPFP resection to confirm the ACL origin on the femoral and tibial sides, especially the femoral footprint in deep flexion of the knee joint. The total IPFP volume was calculated using sagittal MR images before and 6 months after surgery. The patients completed a subjective knee score questionnaire and were assessed for patellar tendon tenderness and pain with the half-squat test or single-leg hop test at 6 months and 2 years postoperatively.

RESULTS

There were no differences in the patient characteristics, including age, sex, BMI, time from injury to surgery, and meniscus tear. The difference in the total size of the IPFP preserved was significant (P = 0.004). However, there were no significant differences in the subjective knee scores. Moreover, there were no differences in the clinical assessment parameters between the IPFP preservation and resection groups.

CONCLUSIONS

The size of the IPFP decreased more in the resection group than in the preservation group at 6 months after surgery. However, partial IPFP resection, which was used to better visualize the origin of the ACL, had no effect on the clinical outcomes, including AKP.

LEVEL OF EVIDENCE

Level II.

Central patellar portal placement frequently provokes anterior knee compartment radiological abnormalities in anterior cruciate ligament reconstruction

PURPOSE

A central patellar (CP) portal can be used to view the native femoral insertion site of the anterior cruciate ligament (ACL). It aids in the drilling of an anatomical tunnel; however, its impact on the patellar tendon and the infrapatellar fat pad remains a concern. The aim of this study was to investigate complications associated with the CP portal use in arthroscopic ACL reconstruction (ACLR).

METHODS

A total of 105 patients (107 knees, 60 females) who underwent ACLR with a CP portal from 2012 to 2017 were included in this study. The mean age was 28.3 ± 12.4 years. All surgeries were single-bundle reconstructions using the trans-tibial technique via the CP and anteromedial portals. Post-operative events, magnetic resonance imaging (MRI), and arthroscopic findings associated with CP portal creation were evaluated.

RESULTS

Five patients (4.7%) had symptomatic postoperative complications, which included two patients with patellar tendonitis and three patients with fibrosis in the anterior knee compartment. Abnormal signal intensity of the patellar tendon on MRI and increased thickness at the CP portal area were found in 18 of 25 knees (72%). Three of 56 knees (5.4%) that underwent second-look arthroscopy showed fibrosis of the infrapatellar fat pad. Seven patients (12.5%) showed hypertrophy of the ligamentum mucosum.

CONCLUSIONS

The rate of symptomatic complications associated with CP portal placement was 4.7%; however, abnormal MRI or follow-up arthroscopy findings were much higher than clinically symptomatic patients. This study suggests that CP portal placement could provoke anterior knee compartment fibrosis or hypertrophy.

LEVEL OF EVIDENCE

IV.

The characteristics of the lobular arrangement indicate the dynamic role played by the infrapatellar fat pad in knee kinematics

The infrapatellar fat pad (IFP) is an intracapsular but extrasynovial structure, located between the patellar tendon, the femoral condyles and the tibial plateau. It consists of white adipose tissue, organised in lobules defined by thin connective septa. The aim of this study is the morphometric and ultrasonographic analysis of IFP in subjects without knee pathology during flexion-extension movements. The morphometric study was conducted on 20 cadavers (15M, 5F, mean age 80.2 years). Ultrasound was performed on 24 volunteers with no history of knee diseases (5M, 19F, mean age: 45 years). The characteristics of the adipose lobules near the patellar tendon and in the deep portion of the IFP were evaluated. Numerical models were provided, according to the size of the lobules. At histological examination, the adipose lobules located near the patellar tendon were larger (mean area 12.2 mm²  ± 5.3) than those at a deeper level (mean area 1.34 mm²  ± 0.7, P < 0.001) and the thickness of the septa of the deepest adipose lobules (mean value 0.35 mm ± 0.32) was greater than that of the superficial one (mean value 0.29 mm ± 0.25, P < 0.001). At ultrasound, the IFP was seen to be composed of very large lobules in the superficial part (mean area 0.29 cm²  ± 0.17 in extension), with a significant reduction in flexion (mean area 0.12 cm²  ± 0.07, P < 0.01). The deep lobules were smaller (mean area 0.11 cm²  ± 0.08 in extension) and did not change their values (mean area 0.19 cm²  ± 0.52 in flexion, P > 0.05). In the sagittal plane, the reduction of thickness of the superficial layer (with large adipose lobules) during flexion was 20.6%, whereas that of the deep layer (with small adipose lobules) was 1.3%. Numerical simulation of vertical loads, corresponding to flexion of the knee, showed that stress mainly developed within the interlobular septa and opposed bulging of the lobules. The characteristics of the lobular arrangement of the IFP (large lobules with superficial septa in the superficial part and small lobules with thick septa in the deep one), significant changes in the areas and perimeters of the superficial lobules, and the reduced thickness of the superficial layer during flexion all indicate the dynamic role played by the IFP in knee kinematics.

Strenuous Treadmill Running Induces a Chondrocyte Phenotype in Rat Achilles Tendons

BACKGROUND Although tendinopathy is common, its underlying pathogenesis is poorly understood. This study aimed to investigate the possible pathogenesis of tendinopathy. MATERIAL AND METHODS In this study, a total of 24 rats were randomly and evenly divided into a control (CON) group and a strenuous treadmill running (STR) group. Animals in the STR group were subjected to a 12-week treadmill running protocol. Subsequently, all Achilles tendons were harvested to perform histological observation or biochemical analyses. RESULTS Histologically, hypercellularity and round cells, as well as disorganized collagen fibrils, were presented in rat Achilles tendon sections from the STR group. Furthermore, our results showed that the expression of aggrecan, collagen type II (Col II), and Sex-Determining Region Y Box 9 (Sox 9) were markedly increased in the STR group compared with that in the CON group. Additionally, the mRNA expression of bone morphogenetic protein-2 (BMP-2) and biglycan was significantly up-regulated in the STR group in contrast to that in CON group. CONCLUSIONS These results suggest that a 12-week strenuous treadmill running regimen can induce chondrocyte phenotype in rat Achilles tendons through chondrogenic differentiation of tendon stem cells (TSCs) by BMP-2 signaling.

Single-Portal Versus Two-Portal Knee Arthroscopy: First Clinical Experience With a New Surgical Technique

This pilot study compared efficacy, morbidity, and complication rates with a new single-portal arthroscopy technique and traditional 2-portal knee arthroscopy. This prospective study evaluated 156 patients who underwent arthroscopic knee surgery, 106 with 2 portals and a traditional arthroscope and instruments and 50 with a single portal and newly designed arthroscopy instruments. Patients who had reconstructive procedures, microfractures, lateral release procedures, advanced osteoarthritis, and revision surgery were excluded, as were obese patients. The same surgeon performed all procedures, and the patient groups had no significant differences in sex, age, types of pathology, surgical treatment, medications given, or rehabilitation protocol. All patients were examined and completed questionnaires 1 week, 1 month, and 3 months postoperatively. The surgeon was blinded to the data. Follow-up was 100%. The single-portal technique was technically feasible for treatment of knee pathology in 49 of 50 patients. The 2-portal technique provided adequate treatment of knee pathology in all 106 cases. No difference was reported in pain level in the recovery room or on postoperative day 2. However, patients in the single-portal group reported less pain on day 4 (P=.04) and day 7 (P=.004) and were less likely to use oral narcotic analgesics (P=.0001). The single-portal group reported better function in activities of daily living at 1 month and less interference with sports participation at 3 months. Complication rates were no different in the 2 groups. The findings showed that the single-portal technique improved functional recovery at 1 month and 3 months postoperatively and may result in less morbidity in some parameters.

Anterior knee symptoms after double-bundle ACL reconstruction with hamstring tendon autografts: an ultrasonographic and power Doppler investigation

PURPOSE

Anterior knee pain related to the donor site is a frequent complication of anterior cruciate ligament reconstruction (ACLR) with bone-patellar tendon-bone autograft tissue. Even when hamstring tendon (HT) grafts are used instead, symptoms such as mild pain and discomfort can still occur. The purpose of this study was to elucidate the pathophysiology of anterior knee symptoms after ACLR with HT autografts.

METHODS

Fifty-seven patients (22 men and 35 women; mean age, 24.7 years) who underwent anatomic double-bundle ACLR with HT autografts were examined 6 months post-operatively. The presence of anterior knee symptoms, anterior knee laxity, range of motion, and muscle strength were assessed. Changes in patellar tendon and infrapatellar fat pad (IFP) morphology and blood flow were also evaluated using ultrasound. Potential variables affecting the presence of anterior knee symptoms were subjected to univariate analysis and multivariate logistic regression analysis to identify independent risk factors.

RESULTS

Six months post-operatively, the total incidence of anterior knee symptoms was 56.1 % (32/57). According to univariate analysis, age, quadriceps strength, and increased blood flow in the IFP were significantly associated with the presence of anterior knee symptoms. Multivariate logistic regression analysis revealed that increased blood flow in the IFP was an independent factor for the presence of anterior knee symptoms (odds ratio 5.0; 95 % confidence interval 1.3-19.9). There were no significant findings inside the patellar tendon.

CONCLUSIONS

Increased blood flow in the IFP was identified as an independent factor for the presence of anterior knee symptoms 6 months after ACLR with HT autografts. The ultrasound evaluation can help to define precisely the origin of anterior knee symptoms after ACLR with HT autografts.

LEVEL OF EVIDENCE

Case series with no comparison groups, Level IV.

T2 relaxometry of the infrapatellar fat pad after arthroscopic surgery

OBJECTIVE

To investigate the T2 relaxation values of the infrapatellar fat pad (IFP) after arthroscopic surgery.

MATERIALS AND METHODS

This study was approved by the institutional review board; all individuals signed informed consent. We performed MRI in 16 knees from 8 subjects. Prior to imaging, each subject had unilateral arthroscopic knee surgery and an asymptomatic non-operated contralateral knee. We used a 10-echo multiple-TE fast-spin echo pulse sequence for creation of T2 relaxation time maps. Two musculoskeletal radiologists independently placed regions of interest in the IFP, suprapatellar subcutaneous and deep intermuscular adipose tissue. Qualitative assessments were performed to assess fibrotic changes affecting patellar retinaculum and IFP. Statistical analyses of T2 values determined differences between groups, correlation with time after surgery, and cut-off values to differentiate groups.

RESULTS

The average time between arthroscopy and imaging was 3.5 ± 0.4 years. IFP of knees with prior surgery had significantly shorter mean T2 values (133 ± 14 ms) compared with control knees (147 ± 8 ms, P = 0.03). There was no significant difference between operated and control knees regarding T2 values of suprapatellar subcutaneous (P = 0.3) or deep intermuscular adipose tissue (P = 0.2). There was no correlation between IFP T2 values and time after surgery (P > 0.2). IFP T2 values ≤ 139 ms had 75 % sensitivity and 88 % specificity in identifying prior arthroscopy.

CONCLUSION

Shortening of T2 relaxation values is present in IFP chronically after arthroscopic surgery and may be an indicator of adipose tissue fibrosis.

Patellar tendinopathy: preliminary surgical results

Background:

Calcific deposits (CaDs) may be related to chronic postoperative pain and may affect function after patellar tendon surgery.

Study Design:

Cross-sectional.

Hypothesis:

We hypothesized that patients with CaDs (+CaDs) would rate lower than those without (−CaDs) on measures of knee function and quality of life.

Methods:

Patients completed the Tegner Lysholm Knee Scoring Scale (Lysholm), Knee Injury and Osteoarthritis Outcome Score (KOOS), the International Knee Documentation Committee Subjective Knee Form (IKDC), and the Tegner Activity Level Scale. Sixteen postsurgical and 16 age-matched controls were tested. Patients +CaDs were 5.6 years older than those patients −CaDs and had 4.2 years of longer elapse since surgery. Bilateral patellar tendons were examined for CaDs with musculoskeletal ultrasound imaging. One-way analysis of variance was used to determine if differences existed among patients +CaDs and −CaDs and healthy controls. Hierarchical logistic regressions were used to determine which variables best predicted the presence of CaDs.

Results:

CaDs were found in 44% (7 of 16) of postsurgical patients, who scored lower than controls on all dimensions of the Lysholm, KOOS, and IKDC. Patients +CaD had lower KOOS scores than controls (symptoms, activities of daily living, and quality of life). Age and time since surgery were both moderately related to the presence of CaDs, and both correctly predicted 71% of patients +CaDs.

Conclusion:

Calcific deposits were found in the patellar tendon of 44% of postsurgical patients, who rated themselves lower on all subjective measures of knee function and quality of life following surgery. Age is an important factor for developing CaDs postsurgery.

Clinical Relevance:

Calcific deposits may be present in patellar tendons following surgery, but their direct role in functional or clinical limitations remains unknown.

Single-portal arthroscopy: report of a new technique

A new technique of single-portal arthroscopy using new instrumentation for arthroscopic knee surgery is reported. The procedure is intended for "targeted" surgery to address limited pathology. The arthroscope, cutters, and biters are all introduced into the joint through 1 portal. The technique is generally applicable to knee arthroscopy for isolated conditions and potentially useful in treating other joints. A 2.9-mm-diameter, light-sensitive, high-definition, 20-cm-long arthroscope is inserted through a 4.6-mm cannula. This arthroscope-cannula combination yields fluid flow mechanics similar to a standard 4-mm arthroscope in a 5.8-mm cannula. A Parallel Portal Cannula (PPC) (Stryker Endoscopy) is applied to the arthroscope cannula, producing a "double-barrel" system for entry into the joint. The PPC allows for sliding and rotational freedom along the axis of the arthroscope cannula but also locks in place once a desired position is achieved. PPC devices are available in zero-length, short (25-mm), and long (55-mm) sizes. Cutters that are bent in the mid shaft are available in 3.5- and 4-mm diameters. The instrumentation system allows both viewing with the arthroscope and passage of working cutters and biters through a single 9- to 10-mm portal. Potential advantages of single-portal arthroscopy include decreased patient morbidity and recovery time while still allowing for adequate treatment of limited knee pathology.

The treatment of patellar tendinopathy

BACKGROUND

Patellar tendinopathy (PT) presents a challenge to orthopaedic surgeons. The purpose of this review is to revise strategies for treatment of PT MATERIALS AND METHODS: A PubMed (MEDLINE) search of the years 2002-2012 was performed using "patellar tendinopathy" and "treatment" as keywords. The twenty-two articles addressing the treatment of PT with a higher level of evidence were selected.

RESULTS

Conservative treatment includes therapeutic exercises (eccentric training), extracorporeal shock wave therapy (ESWT), and different injection treatments (platelet-rich plasma, sclerosing polidocanol, steroids, aprotinin, autologous skin-derived tendon-like cells, and bone marrow mononuclear cells). Surgical treatment may be indicated in motivated patients if carefully followed conservative treatment is unsuccessful after more than 3-6 months. Open surgical treatment includes longitudinal splitting of the tendon, excision of abnormal tissue (tendonectomy), resection and drilling of the inferior pole of the patella, closure of the paratenon. Postoperative inmobilisation and aggressive postoperative rehabilitation are also paramount. Arthroscopic techniques include shaving of the dorsal side of the proximal tendon, removal of the hypertrophic synovitis around the inferior patellar pole with a bipolar cautery system, and arthroscopic tendon debridement with excision of the distal pole of the patella.

CONCLUSION

Physical training, and particularly eccentric training, appears to be the treatment of choice. The literature does not clarify which surgical technique is more effective in recalcitrant cases. Therefore, both open surgical techniques and arthroscopic techniques can be used.

Evaluation and treatment of disorders of the infrapatellar fat pad

The infrapatellar fat pad (IFP), also known as Hoffa's fat pad, is an intracapsular, extrasynovial structure that fills the anterior knee compartment, and is richly vascularized and innervated. Its degree of innervation, the proportion of substance-P-containing fibres and close relationship to its posterior synovial lining implicates IFP pathologies as a source of infrapatellar knee pain. Though the precise function of the IFP is unknown, studies have shown that it may play a role in the biomechanics of the knee or act as a store for reparative cells after injury. Inflammation and fibrosis within the IFP, caused by trauma and/or surgery can lead to a variety of arthrofibrotic lesions including Hoffa's disease, anterior interval scarring and infrapatellar contracture syndrome. Lesions or mass-like abnormalities rarely occur within the IFP, but their classification can be narrowed down by radiographical appearance. Clinically, patients with IFP pathology present with burning or aching infrapatellar anterior knee pain that can often be reproduced on physical exam with manoeuvres designed to produce impingement. Sagittal MRI is the most common imaging technique used to assess IFP pathology including fibrosis, inflammation, oedema, and mass-like lesions. IFP pathology is often successfully managed with physical therapy. Passive taping is used to unload or shorten an inflamed IFP, and closed chain quadriceps exercises can improve lower limb control and patellar congruence. Training of the gluteus medius and stretching the anterior hip may help to decrease internal rotation of the hip and valgus force at the knee. Gait training and avoiding hyperextension can also be used for long-term management. Injections within the IFP of local anaesthetic plus corticosteroids and IFP ablation with ultrasound guided alcohol injections have been successfully explored as treatments for IFP pain. IFP pathology refractory to physical therapy can be approached through a variety of operative treatments. Arthroscopic partial resection for IFP impingement and Hoffa's disease has showed favourable results; however, total excision of the IFP performed concomitantly with total knee arthroplasty (TKA) resulted in worse results when compared with TKA alone. Arthroscopic debridement of IFP fibrosis has been successfully used to treat extension block following anterior cruciate ligament reconstruction, and arthroscopic anterior interval release has been an effective treatment for pain associated with anterior interval scarring. Arthroscopic resection of infrapatellar plicae and denervation of the inferior pole of the patella have also been shown to be effective treatments for refractory infrapatellar pain.

Ectopic chondro-ossification and erroneous extracellular matrix deposition in a tendon window injury model

The acquisition of chondro-osteogenic phenotypes and erroneous matrix deposition may account for poor tissue quality after acute tendon injury. We investigated the presence of chondrocyte phenotype, ossification, and the changes in the expression of major collagens and proteoglycans in the window wound in a rat patellar tendon window injury model using histology, von Kossa staining and immunohistochemistry of Sox 9, major collagens, and proteoglycans. Our results showed that the repair tissue did not restore to normal after acute injury. Ectopic chondrogenesis was observed in 33% of samples inside wound at week 4 while ectopic ossification surrounded by chondrocyte-like cells were observed in the window wound in 50% of samples at week 12. There was sustained expression of biglycan and reduced expression of aggrecan and decorin in the tendon matrix in the repair tissue. The erroneous deposition of extracellular matrix and ectopic chondro-ossification in the repair tissue, both might influence each other, might account for the poor tissue quality after acute injury. Higher expression of biglycan and aggrecan were observed in the ectopic chondro-ossification sites in the repair tissue, suggesting that they might have roles in ectopic chondro-osteogenesis.

The macroscopic arthroscopic anatomy of the infrapatellar fat pad

PURPOSE

Our purpose was to define the macroscopic anatomy of the infrapatellar fat pad (IFP) when viewed at arthroscopy and to document the common variations.

METHODS

Ninety-six consecutive patients between 8 and 50 years of age with no previous knee surgery or fat pad pathology underwent arthroscopic examination of the knee. The fat pad of each patient was observed and described regarding size, color, consistency, and the presence of lobules, villous synovium, and lingulae.

RESULTS

The macroscopic arthroscopic anatomy of the IFP was defined. Male fat pads were larger than female fat pads. Two separate parts were described-medial and lateral-with medial dominence being most typical. The specific normal anatomic appearance of each section was defined regarding size, color, consistency, and attributes. Ligamentum mucosum, as the separation limit between the sections, was found in most knees.

CONCLUSIONS

The macroscopic anatomy of the IFP is described at arthroscopy performed for internal pathology of the knee. Two distinct parts were defined-medial and lateral-with medial dominance. A typical fat pad was yellow and included an infrapatellar lingula (85%), lobulation (65%), and villous synovium (65%). We found a ligamentum mucosum in 79% of cases.

CLINICAL RELEVANCE

Knowledge of the macroscopic anatomy of the IFP and variations will allow the accurate diagnosis of pathology of the fat pad, rather than being a diagnosis of exclusion.