Patellar Insertion Research Articles

Muscle damage during minimally invasive surgical total knee arthroplasty traditional versus optimized subvastus approach

Decreased muscle damage is reported as an advantage of minimally invasive surgical (MIS) approaches in total knee arthroplasty (TKA). The purpose of this study was to evaluate the anatomy of vastus medialis obliquus (VMO) tendon at its patellar insertion as well as to determine the amount and location of muscle damage comparing traditional subvastus approach and optimized subvastus approach. TKAs were performed in ten human cadavers (20 knees). In each specimen, one knee underwent the traditional subvastus approach and the contralateral knee the optimized subvastus approach. The risk of tearing and damaging the VMO muscle during the traditional subvastus approach is significantly higher (70% of the cases) compared to the optimized technique (30%). The amount of damage to the VMO muscle using the traditional subvastus approach was: 80% of the muscle's width in two cases, 60% in three cases, and 30% in two. The damage created by the optimized subvastus approach occurred along the edge of the tendon and the first fibers of the VMO muscle close to the muscle–tendon junction (less than 20% of muscle's width). Clinical studies are needed to determine the functional implications of these findings.

Enthesitis and Related Changes in the Knees in Seronegative Spondyloarthropathies and Skin Psoriasis: Magnetic Resonance Imaging Case-Control Study

To describe enhanced magnetic resonance imaging (MRI) features and characteristic entheseal changes in the knees in patients with seronegative spondyloarthropathy (SpA). The 56 patients included 30 with psoriatic arthritis, 5 with ankylosing spondylitis, 5 with reactive arthritis, 5 with ulcerative colitis (UC), 5 with Crohn's disease, and another 6 with skin psoriasis. Controls were 20 healthy subjects without knee complaints. MRI was performed in all participants, emphasizing entheseal sites. Both knees were studied in 45 (80.3%) patients and one knee in 11 (19.6%). MRI showed evidence of bone marrow edema in 13 (23.2%) patients, cartilaginous erosions in 18 (32.1%), and bone erosions in 9 (16.1%). Enthesitis was found in medial collateral ligaments in 18 (32.1%), lateral collateral ligaments in 8 (14.3%), posterior cruciate ligaments in 3 (5.35%), patellar tendon in 18 (32.1%), biceps femoris insertion in 3 (5.35%), medial patellofemoral ligaments (MPFL) in 5 (8.9%), and lateral patellofemoral ligament in 1 patient (1.8%). In the UC and Crohn's patients (n = 10), 2 had bone erosions and 5 had enthesitis. In the skin psoriasis group (n = 6), one had bone marrow edema; enthesitis was detected in 5 at the patellar tendon insertion and in one in the MPFL. Entheseal-related changes were absent in the controls. This is the first study showing entheseal-related changes in the knees in patients with inflammatory bowel disease or skin psoriasis without clinical arthritis. Enthesitis of the knee on MRI may be an early finding in SpA.

Dual tunnel medial patellofemoral ligament reconstruction for patients with patellar dislocation using a semitendinosus tendon autograft

The purpose of this study was to describe a safer and more anatomical technique of MPFL reconstruction and to report the short-term results. The subjects included 20 patients with patellar dislocation with a mean age of 23. The operation was performed using a double-looped autogenous semitendinosus tendon graft. Two small bone tunnels were made at the medial edge of the patella, mimicking the wide patellar insertion of the MPFL and a bone tunnel was made at the femoral insertion site. The free ends of the graft attached to the patella and the loop end was fixed to the femoral side. Five patients were available for follow-up interviews by telephone and the remaining 15 were directly examined by physical examination and radiographic evaluation at 2 years or longer postoperatively. The average follow-up period was 30 months. Re-dislocation or patellar fracture was not seen in any patients. The average Kujala's score was 96 with a range from 84 to 100. Six patients were classified as excellent and 14 as good, according to the Crosby and Insall grading system. Radiographically, narrowing of the patellofemoral joint space was observed in 2 cases with previous osteochondral fracture out of those who were directly examined. The dual tunnel MPFL reconstruction produces favorable results in subjective and functional assessment of outcome without complications.

Functional bundles of the medial patellofemoral ligament

The purpose of this study was to explore the anatomy and evaluate the function of the medial patellofemoral ligament (MPFL). Anatomical dissection was performed on 12 fresh-frozen knee specimens. The MPFL is a condensation of capsular fibers, which originates at the medial femoral condyle. It runs transversely and inserts to the medial edge of the patella. With the landmark of the medial femur epicondyle (MFE), the femoral origination was located: just 8.90±3.27mm proximally and 13.47±3.68mm posteriorly to the MFE. The most interesting finding in present study was functional bundles of its patellar insertion. Approximately from the femoral origination point, fibers of the MPFL form two relatively concentrated fiber bundles: the inferior-straight bundle and the superior-oblique bundle. The whole length of each was 71.78±5.51 and 73.67±5.40mm, respectively. The included angle between bundles was 15.1°±2.1°. Although the superior-oblique bundle and the inferior-straight bundle run on the patellar MPFL inferiorly and superiorly, respectively, as their name indicates, the two bundles are not entirely separated, which make MPFL one intact structure. The inferior-straight bundle is the main static soft tissue restraints where the superior-oblique bundle associated with vastus medialis obliquus (VMO) is to serve as the main dynamic soft tissue restraints. So this finding may provide the theoretical foundation for the anatomical reconstruction of the MPFL and shed lights on the future researchers.

Magnetic Resonance Imaging Characteristics of the Medial Patellofemoral Ligament Lesion in Acute Lateral Patellar Dislocations Considering Trochlear Dysplasia, Patella Alta, and Tibial Tuberosity–Trochlear Groove Distance

The objective of this study was to analyze the injury patterns of the medial patellofemoral ligament (MPFL) in acute lateral patellar dislocations (LPDs) considering the anatomically relevant factors of patellar instability. Knee magnetic resonance images were collected from 73 patients within 7 weeks after LPD, and the injury patterns of the MPFL were evaluated for trochlear dysplasia, for patellar height, and for the tibial tuberosity-trochlear groove (TT-TG) distance. Injury to the MPFL was found in 98.6% of the patients (72 of 73) after the acute LPD, with a complete tear in 51.4% (37 of 72), most frequently localized at the femoral attachment site, and a partial tear in 48.6% (35 of 72). Injury to the femoral origin (Fem), to the midsubstance (Mid), and to the patellar insertion (Pat) of the MPFL was found in 50.0% (36 of 72), 13.9% (10 of 72), and 13.9% (10 of 72), respectively. More than 1 site of injury was found in 22.2% (16 of 72), most frequently as a combined injury at the femoral origin and at the patellar insertion sites (Pat+Fem) (13 of 16). The study population, as well as the Pat, Fem, and Pat+Fem subgroups, showed significantly different values of trochlear dysplasia and patellar height when compared with the control group, whereas the data of the Mid group were not significantly different. In addition, injury at the patellar insertion (Pat) was accompanied by a significantly increased TT-TG distance when compared not only with the control group but also with the Fem, Mid, and Pat+Fem groups. The data from our study indicate that patterns of MPFL injury depend on trochlear dysplasia, patellar height, and TT-TG distance. They show a new aspect in the complex interplay between active, passive, and static stabilizers of the patellofemoral joint. Level IV, diagnostic case-control study.

Failure of the Patellar Tendon with the Patella Everted versus Noneverted in a Matched-Pair Cadaver Model

Avoidance of patellar eversion during total knee arthroplasty may help to prevent injury to the patellar tendon. The purpose of this study was to compare the load-to-failure of the everted versus the noneverted patella in a cadaveric model. Fourteen cadaver knees (seven pairs) were loaded to failure with the patella everted in one knee and not everted in the other. Mean load-at-ultimate failure in the patella-everted group was 1,111 ± 572N, and in the patella-noneverted group was 1,621 ± 683N (p = 0.01). Additionally, loads-at-initial-partial failure were lower (p = 0.04) in the patella-everted compared to the patella-noneverted group, 573 ± 302N versus 1,115 ± 358N, respectively. A partial failure of the patellar tendon occurred in 100% of the everted specimens, whereas only 57% of the noneverted specimens had partial failure. These findings suggest patella eversion may lead to failure of the patellar insertion at lower loads than when the patella is not everted.

Stiffness Associated With Total Knee Arthroplasty

Multiple factors may lead to stiffness after total knee arthroplasty (TKA), including patient diagnosis, preoperative range of motion (ROM), prosthetic geometry used, surgical technique, intraoperative ROM after capsular closure, postoperative rehabilitation, and wound healing factors. An ipsilateral arthritic hip can also inhibit postoperative recovery and lead to knee stiffness. Exposure of the ankylosed knee can be difficult. One must take care to avoid excessive stress on the patellar tendon insertion leading to patellar tendon avulsion. The 2 most common methods to facilitate exposure are a proximal release or a tibial tubercle osteotomy. When patients fail to achieve satisfactory ROM after TKA, manipulation under anesthesia is considered. It is usually performed approximately 6 weeks postoperatively. The best indicator of each patient's potential is his or her intraoperative flexion against gravity with the capsule closed at the end of the procedure.

0226: Polydocanol Use and Success

This workshop is designed to introduce you to a relatively “new “pain relief procedure with the use of ultrasound guidance. Polidocanol (Aethoxysklerol®) is a sclerosing agent used to sclerose neo-vascularisation. This change is related to tendinosis of the tendon. With this change in the tendon, neo-vascularisation occurs to aid in the repair phase. Unfortunately, with new blood flow small nerves also infiltrate and subsequently cause pain on movement- particularly in loading. Under ultrasound guidance it is possible to demonstrate the neo-vascularisation of the structure with the use of colour Doppler. The “feeder” vessel/s is identified and ultrasound is used to the guide the needle into the correct region. Once the vessel/s are demonstrated the Polidocanol is injected into the vessel, and subsequently the vessels are sclerosed /obliterated immediately. With the use of ultrasound and the guiding of the needle the accuracy is greatly increased, therefore, there is a greater degree of confidence that the correct structures have been sclerosed. This gives a better outcome for the patient. The theory behind this type of pain relief is, if there is decreased neo-vascularisation, there is decreased pain, the patient may commence light exercise and hopefully regain full movement - pain free. This technique is predominately used in the “loading “tendons. These are the Achilles tendon, patellar tendon, lateral elbow - common extensor origin, quadriceps tendon at patellar insertion - and some studies have also included the flexor tendons of the hands.

0313: Knee Tendons and Ligaments. Anatomy and Pathology

In the knee, particular strengths of US include the ability to assess traumatic disease affecting tendons and some ligaments. In the quadriceps tendon, US is able to distinguish partial from complete tears thus helping clinical examination that is often misleading. In partial-thickness tears, the superficial tendon layer (from the rectus femoris) is the first involved, followed by the intermediate one (from the vastus medialis and lateralis). In complete tears, the tendon can be retracted at variable distance: the medial and lateral patellar retinacula should also be carefully evaluated because they are often involved. In patellar tendinosis (jumper's knee), chronic microtrauma between the undersurface of the patellar insertion and a prominent patellar tip has been assumed to be a causative factor for chronic impingement and secondary degenerative changes of the patellar tendon. Complete patellar tendon tears may follow a direct local injury or represent the end stage chronic tendinopathy. On the medial knee, MCL injuries can be readily diagnosed with US. Partial tears most often affect the meniscofemoral ligament and can be difficult to differentiate from complete ruptures. Pes anserinus tendinopathy is rare and presents with thickened, hypoechoic tendons and bony cortex irregularities resulting from traction injury. On the lateral knee, chronic local impingement of the iliotibial band against the lateral condyle may lead to friction, local inflammation and pain, the so called “runner's knee”. When inflamed, the bursa between the iliotibial band and the lateral condyle is distended by fluid and can be associated with iliotibial band thickening. In the intercondylar fossa, the middle and distal thirds of the PCL can be demonstrated with US as a deep thick hypoechoic band. Ganglion cysts arising in close proximity to the cruciate ligaments can be occasionally identified with US as incidental findings. A rare tendon-related pathology of the posterior knee is the popliteal artery entrapment syndrome. This syndrome is related to compression of the popliteal artery secondary to the anatomic relationships between the vessel and an abnormal medial head of the gastrocnemius or popliteus. When examining the distal biceps femoris, US scanning should be extended cranially to include the musculotendinous junction as it is a common site of sport-related injuries.

Anatomical double-bundle MPFL reconstruction with an aperture fixation

Since biomechanical studies have shown that the medial patellofemoral ligament (MPFL) is the main restraint against lateral patella displacement, reconstruction of the MPFL has become an accepted method of restoring patellofemoral stability and numerous techniques were described. Due to biomechanical examinations and clinical results, an anatomical double-bundle reconstruction of the "sail-like" MPFL is a reasonable method for achieving stability during complete extension and lower flexion degree. This method also serves to avoid rotation of the patella, providing immediate stability throughout the normal range of motion. However, until today, an aperture fixation technique at the patellar insertion with two bundles has not been described previously. This technique can provide an immediate stability to allow an early rehabilitation with full range of motion.

Open Wedge High Tibial Osteotomy: A Roentgenographic Comparison of a Horizontal and an Oblique Osteotomy on Patellar Height and Sagittal Tibial Slope (SS-62)

Medial opening wedge (OW) high tibial osteotomy (HTO) preserves bone stock while having to only perform one cut, with the advantage of intra-operative adjustment to the desired correction. However, several studies showed that conventional supratubercle horizontal OW is associated with decreasing patellar height and increasing the sagittal tibial slope; both of which can also potentially affect future conversion to a TKR. We hypothesized that performing an oblique osteotomy at the level or distal to the patella tendon insertion could decrease the osteotomy's effects on lowering the patella and increasing the sagittal tibial slope. Hence, the purpose of this study is to evaluate the radiographic effects of a horizontal osteotomy made proximal to the patellar tendon insertion versus on oblique osteotomy made at the level or distal to the patellar tendon insertion on the shift in coronal weight bearing line, sagittal tibial slope and patellar height. A retrospective review of all open wedge HTO cases done by the senior author from January 1998 to August 2005 was performed. Patients were excluded if the indication for surgery was instability or if they had simultaneous ligament repair. Two consecutive cohorts are compared in this study. Initially, the surgeon performed 22 HTO with a horizontal cut proximal to the patellar tendon insertion and a subsequent 19 knees had an HTO with a more distal oblique cut made which would cross at the level or occasionally, distal to, the patella tendon insertion.. The HTO was then fixed open with the appropriate size first generation non-locking Puddu(r) plate (Arthrex, Naples, Fl, USA) (Figure 2). In both groups, the Puudu(r) plate was placed as posteriorly as possible to minimize the increase in sagittal tibial slope. Either autogenous tri-cortical iliac crest bone graft or femoral head allograft and bone substitute were inserted in the osteotomy in all but one patient which had an opening less then 7.5 mm. The patellar height as measured by Blackburne and Peel ratio was decreased in the horizontal group from 0.85 ± 0.16 to 0.67 ± 0.12 post-operatively signifying a lowering of the patella (Table 2). The oblique group trended toward a change in patellar height as the ratio only decreased by 0.05 from a pre-operative value of 0.89 ± 0.09 to 84 ± .13 (p=0.07). The sagittal tibial slope increased following a horizontal HTO from 7.7 ± 4.6o to 10.7 ± 3.8o; this change was statistically significant (p<0.001) In the oblique group however, the slope was not significantly increased: 6.5 ± 4.0o pre-operatively to 7.0 ± 4.1o post-operatively (p=0.90). The more distal oblique osteotomy did not statistically affect the patellar height or the sagittal tibial slope while still allowing a similar coronal correction to the proximal horizontal group. Additionally, the more distal oblique osteotomy has the advantage of a technically easier exposure being distal to the periarticular capsule and allowing easier access to the posterior aspect of tibia for neurovascular protection. Caution should be exercised not to osteotomize too distally into lateral cortical bone to avoid instability and early loss of correction.

Influence of patellar ligament insertion angle on quadriceps usage during walking in anterior cruciate ligament reconstructed subjects

Reduced quadriceps contraction has been suggested as an adaptation to prevent anterior tibial translation in anterior cruciate ligament (ACL)-deficient knees. This theory has been supported by a recent study that peak knee flexion moment (thought to be created by a decrease of quadriceps contraction) during walking was negatively correlated with patellar ligament insertion angle (PLIA) in ACL-deficient knees, but not in contralateral, uninjured knees. In addition, the PLIA was significantly smaller in ACL-deficient knees than in contralateral, uninjured knees. However, it is unknown whether ACL reconstruction restores the PLIA or whether the relationship between the PLIA and knee flexion moments previously observed in ACL-deficient knees disappears. This study tested the following hypotheses: (1) The PLIA of ACL-reconstructed knees is significantly smaller than the PLIA of uninjured contralateral knees; (2) Peak knee flexion moment (balanced by net quadriceps moment) during walking is negatively correlated with the PLIA in ACL-reconstructed knees. The PLIA of 24 ACL-reconstructed and contralateral knees were measured using MRI, and peak knee flexion moments during walking were measured. Results showed that the PLIA of ACL-reconstructed (22.9 +/- 4.4 degrees) knees was not significantly smaller (p = 0.09, power = 0.99) than the PLIA of contralateral (24.1 +/- 4.8 degrees) knees. Peak knee flexion moment was not correlated with the PLIA following ACL reconstruction (R2 = 0.016, power = 0.99). However, the magnitude of the knee flexion moment remained significantly lower in ACL-reconstructed knees. In summary, this study has shown that the PLIA of ACL-reconstructed knees returned to normal and that patients no longer adapt their gait in response to the PLIA, though quadriceps function did not return to normal levels.

Transient medial patellar dislocation: injury patterns at US and MR imaging

Medial dislocation of the patella is an unusual entity. It is usually an iatrogenic complication of surgical lateral retinacular release. We describe the clinical, ultrasound (US), and magnetic resonance (MR) imaging features of a transient medial patellar dislocation in a 19-year-old patient with trochlear groove dysplasia presenting no surgical history. US showed acute injury to the lateral patellar retinaculum with complete avulsion at its patellar insertion. MR imaging confirmed the complete tear of the lateral patellar retinaculum and disclosed contusion of the anteromedial portion of the medial femoral condyle and lateral patella. This case is noteworthy because the injury patterns of patellar soft tissue restraints differ markedly from the classical features of lateral patellar dislocation.

Open Wedge High Tibial Osteotomy

Background In patients with unicompartmental medial knee arthritis, medial opening wedge high tibial osteotomy is used to shift the mechanical weightbearing line laterally to reduce pain and improve function. There have been concerns that opening wedge high tibial osteotomy is associated with a reduction of patellar height and increase in the sagittal posterior tibial slope, both of which can adversely affect the final result. Hypothesis A more distal oblique osteotomy at the level of insertion of the patellar tendon should decrease these effects when compared with a horizontal osteotomy made proximal to the patellar tendon insertion. Study Design Cohort study; Level of evidence, 3. Methods Review of 22 horizontal and 19 oblique high tibial osteotomies with a mean follow-up of 4.2 ± 1.8 years (mean ± SD) was performed. Anatomic tibiofemoral angle, mechanical weightbearing line, medial coronal tibial plateau angle, patellar height (Blackburne and Peel ratio), and sagittal tibial slope were measured. Results In both groups, the weightbearing line was equally shifted toward the center of the plateau. In the horizontal group, the Blackburne and Peel ratio decreased from 0.85 ± 0.16 to 0.67 ± 0.12, and the sagittal tibial slope was increased from 7.7° ± 4.6° to 10.7° ± 3.8° (P < .001). In comparison, the oblique group did not show any significant postoperative changes for these 2 parameters. In the oblique group, 2 patients sustained loss of correction and early failure when the osteotomy remained below the metaphyseal flare on the lateral cortex. Conclusion The oblique osteotomy group showed more normalized postoperative sagittal tibial slope and patellar height. Caution should be exercised not to osteotomize too distally.

Rupture of the quadriceps tendon

A five-month-old, male, 16 kg, mixed breed dog was presented for an acute non-weight bearing lameness of the right hind limb. A subtotal avulsion of the quadriceps tendon at its patellar insertion was diagnosed through radiography and ultrasonography. Two nylon sutures secured with a stainless steel crimp were placed in a locking loop pattern in the quadriceps tendon and through a transverse 2.7 mm drill-hole in the patella. No external coaptation was used postoperatively. A full functional recovery was observed, and was followed for one year postoperatively. Quadriceps tendon rupture has not been described in the veterinary literature to our knowledge; in humans, quadriceps tendon rupture is a well known entity, often due to systemic disease resulting in weakening of the tendinous structures. In the case presented herein, the dog's history, young age and location, without underlying biochemical abnormalities, led us to believe that the observed lesion was of traumatic origin. The surgical treatment performed was based on that performed in humans and also that which has been investigated experimentally in the dog.

Does Osgood-Schlatter Disease exist in the dog?

Osgood-Schlatter disease (OSD) is a condition affecting human adolescents in which there is partial separation of bone fragments from the tibial tuberosity at the site of insertion of the patellar ligament to the tibial tuberosity. Tensile trauma seems to be the most likely aetiology. Clinical signs in people consist of swelling and pain at the proximal part of the tibial tuberosity and around the distal end of patellar ligament. Radiographs frequently show small ossicles at the patellar ligament insertion. Conservative treatment is usually curative. The term OSD has also been used for the canine patient. However, radiographs of these patients typically show an enlarged radiolucent line at the apophyseal plate of the tibial tuberosity. This finding is consistent with a mild avulsion fracture of the canine tibial tuberosity. Based on the radiographic differences between the two species, it seems more appropriate to use the term OSD only for people. The purpose of this paper is to review the literature on OSD in people and the reports of injuries to the proximal tibial tuberosity in dogs. In addition, a new classification system for tibial tuberosity avulsion injuries in the immature dog is proposed, with an algorithm for management of this injury.

Mechanical resistance of the modified stabilization method for the tibial tuberosity advancement technique: ex vivo experimental study in dogs

The present study aimed to evaluate a modification of the stabilization method of the tibial tuberosity advancement technique (TTA), originally described for stabilization of the cranial cruciate deficient stifle. Ten adult mongrel dogs with weights ranging from 25 to 30kg were used. After euthanasia, the hind-limbs were divided into two groups: G1 - test (n=10), and G2 - control (n=10) represented by the contra lateral limb. The test group was submitted to the modified TTA technique, stabilized by one shaft screw in craniocaudal position and a titanium cage inserted at the osteotomy site. The position of the patellar tendon, 90° in relation to the tibial plateau, and the correct position of all implants were confirmed radiographically after surgery. Posteriorly, in both groups, limbs were harvested and tibias collected with their respectively patellar tendon insertion preserved for the mechanical resistance test. The fixation of the tibial tuberosity with a shaft screw and titanium cage resulted in resistance compatible with the normal physiological forces transferred to the hind-limbs during locomotion. The biomechanical tests confirmed the viability of the method performed for the tibial tuberosity fixation and support future clinical trials to validate the technique.

Metric Measurements and Attachment Levels of the Medial Patellofemoral Ligament: An Anatomical Study in Cadavers

OBJECTIVETo determine the metric measurements and to verify the attachment levels of the medial patellofemoral ligament in human cadavers.METHODSSeventeen knees (eight right and nine left knees) from 10 cadavers (nine male and one female) were dissected and stored in a 10% formaldehyde solution. All of the knees were whole and did not show any macroscopic signs of injuries.RESULTSThe medial patellofemoral ligament was present in 88% of the knees studied, localized transversally between the medial femoral epicondyle and the medial margin of the patella. Its dimensions were quite variable, even between the knees of the same individual. The width of the patellar insertion ranged from 16 to 38.8 mm, with a mean of 27.90 mm, and its mean length was 55.67 mm. The margins of the ligament were concave or rectilinear. At the upper margin, the concave form predominated and was better characterized, while at the lower margin, the rectilinear form predominated.CONCLUSIONSThe medial patellofemoral ligament is a very distinct structure with variable anatomical aspects and is always located in a plane inferior to the vastus medialis obliquus muscle.

Estudo anatômico do ligamento patelofemoral lateral em joelho de cadáveres

OBJECTIVES: To describe the lateral patellofemoral ligament (LPFL) after anatomical dissection of fresh cadaver knees. The literature shows a particular interest for the LPFL. Such special attention is due to its anatomical and biomechanical importance, and also due to the need to reconstruct the ligament in the cases of medial patellar instability. METHODS: The LPFL was studied in 20 knees of 20 fresh cadavers by means of anatomical dissections. The dissections were standardized and the data were noted down and forwarded to statistical analysis. RESULTS: The LPFL presented a mean 16.05 mm width (standard deviation of 2.48), 42.10 mm length (standard deviation of 8.84). The femoral insertion was found at the lateral femoral epicondyle and with a fan-like expansion of the fibers, predominantly in the posterior region proximal to the lateral epicondyle. In the patella, the insertion found was in the upper-lateral region (in the middle of the upper third of the coronal plan), also with expanded fibers, but less intensely so. In the sagittal plan, the ligament was located in the posterior half of the border of the patella. The LPFL was isolated in the second lateral retinacular layer, the deep transverse retinaculum. CONCLUSION: The LPFL is located in the deep transverse retinacular layer with the presence of a fan-like expansion of its fibers both in the femoral and in the patellar insertions. The insertion is more posterior and proximal at the femoral epicondyle and in the posterior half of the patellar border (sagittal plan) and in the upper-lateral aspect.

Sonographic Evaluation of the Injuries After Traumatic Patellar Dislocation in Adolescents

Traumatic patellar dislocation (TPD) may be associated with other injuries requiring additional treatment. The superficial localization of the knee extensor apparatus and knee articular cartilage make them accessible to sonographic evaluation (ultrasonography [USG]). Prospective analysis of the value of USG in TPD. In 21 patients, 22 knees were examined by USG after clinical and routine radiographic evaluations. Based on USG findings, operative or nonoperative treatment was done (15 and 7 cases, respectively). In 17 knees, lesions of the medial patellofemoral ligament (MPFL) fibers were visible. In 16 knees, avulsion fractures of the patellar insertion of the MPFL were identified. Injuries of the femoral attachment of the MPFL or intramuscular hematoma of the vastus medialis obliquus (VMO) were present in 7 knees. Eleven osteochondral loose bodies and 1 nondisplaced osteochondral fracture were detected in 11 knees. Corresponding osteochondral lesions were localized in all cases. An osteochondral loose body that was identified by USG was confirmed intraoperatively or by computed tomographic scan in 91.6%, the osteochondral lesion localization in 81.8%, and avulsion fracture of the patellar attachment of the MPFL in 100% of knees. Overall, the USG findings were confirmed by these methods in 88.2% of knees. Ultrasonography is highly efficient in determining the extent of injuries after TPD in adolescents. Ultrasonography allows visualization of loose bodies, localization of osteochondral lesions, and, using a dynamic modification, allows precise assessment of the functional status of the MPFL. II.