Introduction Can be classified into the following acute traumatic occurs equally by gender may occur from a direct blow (ex. helmet to knee collision in football) chronic patholaxity recurrent subluxation episodes occurs more in women associated with malalignment habitual usually painless occurs during each flexion movement pathology is usually proximal (e.g. tight lateral structures - ITB and vastus lateralis) Epidemiology demographics most commonly occurs in 2nd-3rd decades of life risk factors general factors ligamentous laxity (Ehlers-Danlos syndrome) previous patellar instability event "miserable malalignment syndrome" a term named for the 3 anatomic characteristics that lead to an increased Q angle femoral anteversion genu valgum external tibial torsion / pronated feet anatomical factors osseous patella alta causes patella to not articulate with sulcus, losing its constraint effects trochlear dysplasia excessive lateral patellar tilt (measured in extension) lateral femoral condyle hypoplasia muscle dysplastic vastus medialis oblique (VMO) muscle overpull of lateral structures iliotibial band vastus lateralis Pathophysiology mechanism usually on noncontact twisting injury with the knee extended and foot externally rotated patient will usually reflexively contract quadriceps thereby reducing the patella osteochondral fractures occur most often as the patella relocates direct blow less common ex. knee to knee collision in basketball, or football helmet to side of knee Anatomy Passive stability medial patellofemoral ligament (MPFL) femoral insertion origin is between medial epicondyle and adductor tubercle is usual site of avulsion of MPFL is primary restraint in first 20 degrees of knee flexion patellar-femoral bony structures account for stability in deeper knee flexion trochlear groove morphology, patella height, patellar tracking Dynamic stability provided by vastus medialis (attaches to MPFL) Presentation Symptoms complaints of instability anterior knee pain Physical exam acute dislocation usually associated with a large hemarthrosis absence of swelling supports ligamentous laxity and habitual dislocation mechanism medial sided tenderness (over MPFL) increase in passive patellar translation measured in quadrants of translation (midline of patella is considered "0"), and also should be compared to contralateral side normal motion is <2 quadrants of patellar translation lateral translation of medial border of patella to lateral edge of trochlear groove is considered "2" quadrants and is considered abnormal amount of translation patellar apprehension passive lateral translation results in guarding and a sense of apprehension increased Q angle J sign excessive lateral translation in extension which "pops" into groove as the patella engages the trochlea early in flexion associated with patella alta Imaging Radiographs rule out fracture or loose body medial patellar facet (most common) lateral femoral condyle AP views best to evaluate overall lower extremity alignment and version lateral views best to assess for trochlear dysplasia evaluate for patellar height (patella alta vs baja) Blumensaat's line should extend to inferior pole of the patella at 30 degrees of knee flexion Insall-Salvati method normal between 0.8 and 1.2 Blackburne-Peel method normal between 0.5 and 1.0 Caton Deschamps method normal between 0.6 and 1.3 Plateau-patella angle normal between 20 and 30 degrees Sunrise / Merchant views best to assess for lateral patellar tilt lateral patellofemoral angle (normal is an angle that opens laterally ) congruence angle (normal is -6 degrees) CT scan TT-TG Distance measures the distance between 2 perpendicular lines from the posterior cortex to the tibial tubercle and the trochlear groove >20mm usually considered abnormal MRI help further rule out suspected loose bodies osteochondral lesion and/or bone bruising medial patellar facet (most common) lateral femoral condyle tear of MPFL tear usually at medial femoral epicondyle Adult Treatment Nonoperative NSAIDS, activity modification, and physical therapy indications mainstay of treatment for first time patellar dislocator without any loose bodies or intraarticular damage habitual dislocator techniques short-term immobilization for comfort followed by 6 weeks of controlled motion emphasis on strengthening closed chain short arc quadriceps exercises Quad strengthening core and hip strengthening to improve limb positioning and balance (hip abductors, gluteals, and abdominals) patellar stabilizing sleeve or "J" brace consider knee aspiration for tense effusion positive fat globules indicates fracture Operative Arthroscopic debridement (removal of loose body) vs Repair with or without stabilization indications displaced osteochondral fractures or loose bodies may be an indication for operative treatment in a first-time dislocator techniques arthroscopic vs open removal versus repair of the osteochondral fragment primary repair with screws or pins if sufficient bone available for fixation MPFL repair indications acute first time dislocation with bony fragment techniques direct repair when surgery can be done within first few days no clinical studies support this over nonoperative treatment MPFL reconstruction with autograft vs allograft indications recurrent instability no significant underlying malalignment techniques gracilis or semitendinosus commonly used (stronger than native MPFL) femoral origin can be reliably found radiographically (Schottle point) Fulkerson-type osteotomy (anterior and medial tibial tubercle transfer) indications may be used in addition to MPFL or in isolation for significant malalignment TT-TG >20mm on CT techniques anteromedialized displacement of osteotomy and fixation correct TT-TG to 10-15mm (never less than 10mm) tibial tubercle distalization indications patella alta techniques distal displacement of osteotomy and fixation lateral release indications isolated release no longer indicated for instability only indicated if there is excessive lateral tilt or tightness after medialization technique arthroscopic trochleoplasty indications rarely addressed (in the USA) even if trochlear dysplasia present may consider in severe or revision cases techniques arthroscopic or open trochlear deepening procedure Pediatric Treatment Same principles as adults in general but must preserve the physis do not do tibial tubercle osteotomy (will harm growth plate of proximal tibia) Complications Recurrent dislocation redislocation rates with nonoperative treatment may be high (15-50%) at 2-5 years Medial patellar dislocation and medial patellofemoral arthritis almost exclusively iatrogenic as a result of prior patellar stabilization surgery
Medial Retinacular Plication (Modified Insall ) Technique guide are not considered high yield topics for orthopaedic standardized exams including the ABOS, EBOT and RC. Authors: Orthobullets Team MPFL Reconstruction - Pediatric and Adolescent Technique guide are not considered high yield topics for orthopaedic standardized exams including the ABOS, EBOT and RC. Authors: Orthobullets Team MPFL Reconstruction - Adult Technique guide are not considered high yield topics for orthopaedic standardized exams including the ABOS, EBOT and RC. Authors: Brandon Erickson
QUESTIONS 1 of 11 1 2 3 4 5 6 7 8 9 10 11 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ12.72) Which of the following structures attaches between the medial epicondyle and adductor tubercle of the femur? Review Topic QID: 4432 1 Medial head of gastrocnemius 7% (322/4893) 2 Medial collateral ligament 18% (863/4893) 3 Semimembranosus 3% (128/4893) 4 Adductor magnus 6% (303/4893) 5 Medial patellofemoral ligament 67% (3260/4893) Select Answer to see Preferred Response PREFERRED RESPONSE 5 (OBQ10.188) A 27-year-old football player sustains an acute lateral patellar dislocation. Which of the following is the most likely site of injury seen on MRI? Review Topic QID: 3281 1 Midsubstance oblique retinacular ligament rupture 16% (373/2323) 2 Soft-tissue avulsion of medial patellofemoral ligament 56% (1306/2323) 3 Midsubstance medial patellofemoral ligament rupture 18% (414/2323) 4 Partial quadriceps tendon rupture 3% (73/2323) 5 Bony avulsion of medial patellofemoral ligament 6% (144/2323) Select Answer to see Preferred Response PREFERRED RESPONSE 2 (OBQ07.112) You see a patient in the emergency room with an acute lateral patellar dislocation. Which of the following factors is associated with the highest risk of persistent patellar instability? Review Topic QID: 773 1 Younger age 2% (10/457) 2 Increased Q-angle 14% (62/457) 3 Male gender 0% (1/457) 4 Previous patellar instability event 82% (374/457) 5 Amount of lateral patellar tilt 1% (5/457) Select Answer to see Preferred Response PREFERRED RESPONSE 4 (OBQ11.188) Which of the following best describes the radiographic landmarks on a lateral radiograph for locating the femoral attachment of the medial patellofemoral ligament (MPFL) during reconstruction? Review Topic QID: 3611 1 The intersection of a line extended from the middle of the shaft and Blumensaat's line 7% (204/2748) 2 Anterior to a line extended from the middle of the shaft and Blumensaat's line 6% (175/2748) 3 Posterior to a line extended from the posterior cortex of the shaft and distal to Blumensaat's line 7% (201/2748) 4 Anterior to a line extended from the posterior cortex of the shaft and distal to Blumensaat's line 14% (378/2748) 5 Anterior to a line extended from the posterior cortex of the shaft and proximal to Blumensaat's line 64% (1760/2748) Select Answer to see Preferred Response PREFERRED RESPONSE 5 (OBQ07.30) An athlete sustains a traumatic patellar dislocation. The MRI shows a hemarthrosis with a floating osteochondral fragment. Which of the following is the most likely site of origin for the loose fragment? Review Topic QID: 691 1 The lateral patellar facet 12% (166/1380) 2 The medial patellar facet 84% (1164/1380) 3 The odd patellar facet 1% (11/1380) 4 The medial trochlea 2% (29/1380) 5 The central trochlea 1% (9/1380) Select Answer to see Preferred Response PREFERRED RESPONSE 2 (OBQ04.46) All of the following are predisposing factors for lateral patellar dislocation in a native knee EXCEPT? Review Topic QID: 107 1 Excess femoral internal rotation 3% (15/539) 2 Excess external tibial rotation 15% (83/539) 3 Lateral femoral condylar hypoplasia 2% (11/539) 4 Increased Q-angle 2% (9/539) 5 Insufficiency of the vastus lateralis 78% (418/539) Select Answer to see Preferred Response PREFERRED RESPONSE 5 (OBQ08.49) A high school softball player has chronic activity-related anterior knee pain without a history of instability. Which radiographic measurement is used to indicate when a lateral retinacular release may be helpful? Review Topic QID: 435 1 Congruence angle 14% (213/1480) 2 Q angle 22% (329/1480) 3 Sulcus angle 9% (128/1480) 4 Lateral patello-femoral angle 54% (800/1480) 5 Patellar height index 0% (6/1480) Select Answer to see Preferred Response PREFERRED RESPONSE 4
Video Spotlight: MPFL Reconstruction - Matthew T. Provencher, MD , CAPT, MC, USNR (2.39, 2018 Winter SKS) Knee & Sports - Patellar Instability - All WINTER SKS: 2018 SHOULDER, KNEE, & SPORTS MEETINGVideo Spotlight: MPFL Reconstru... 7/16/2018 239 views When should I perform a Trochleoplasty? - Andreas B. Imhoff, MD (2.38, 2018 Winter SKS) Knee & Sports - Patellar Instability - All WINTER SKS: 2018 SHOULDER, KNEE, & SPORTS MEETINGWhen should I perform a Trochle... 7/16/2018 141 views When should I perform an Osteotomy for Patellar Instability? - Robin West, MD (2.37, 2018 Winter SKS) Knee & Sports - Patellar Instability - All WINTER SKS: 2018 SHOULDER, KNEE, & SPORTS MEETINGWhen should I perform an Osteot... 7/16/2018 185 views See More See Less
Patellar Dislocation with Loose Chondral Fragment and Medial Facet Fx (C2390) Knee & Sports - Patellar Instability HPI - 14 year old playing soccer and sustained twisting injury. Fell to the ground. Presented to me with swollen knee. Place in KI and MRI obtained. MRI shows significant lateral patellar subluxation with some tilt. Trochlear dysplasia (flat trochlea) Large medial facet chondral deficiency with loose fragment in suprapatellar pouch. Medial patellar facet fx. MPFL seems to be attached to medial fx fragment. I measured TTTG to be 19-20 I did not appreciate patella alta. What are your guys thoughts? Scope and see if cartilage piece can be fixated? Or let medial facet fx heal then go back and do tibial tubercle transfer with lateral release, medial plication / mpfl and denovo for chondral defect? What would be your next step in treatment of this patient? 10/1/2015 136 3 16 Patella dislocation with large loosebody (C1942) Knee & Sports - Patellar Instability HPI - 25 yo laborer that was dancing at his bachelor party with first-time patella dislocation. evidence of large (approx 2cm)chondral loose body from medial facet with small amount of bone attached to small portion of loose body. TT-TG ratio is normal. In addition to MPFL repair/recon how would you treat the largely chondral fragment with small amounts of bony attachment. would your treatment include attempted fixation of segments with attached bone, debridement, OATS, microfracture? would you use bioscrews or acutrax metal screws for any attempted refixation?? deNovo is not available due to insurance restriction. what would your treatment be for the largely chondral defect with small areas of bony attachment? 6/15/2014 210 4 9 Patella instability and ACL tear (C1922) Knee & Sports - Patellar Instability HPI - 27 yr F. Multiple knee instability episodes. Many patellar dislocations when teenager. Was a dancer. Has generalized ligamentous laxity. Had MPFL repair and lateral release 12 years ago. Did not do well after surgery. Main complaint is instablity. On exam very lax patella. + apprehension. 4 quadrant excursion. + lachman Failed conservative tx. On imaging: + patella alta Caton deshamps 1.3 Trochlear dysplasia Dejour type C + acl tear What to do now? Tibial tubercle tx with distalization and revision mpfl reconstruction When to reconstruct ACL? Do all one surgery or stage? Surgical options? 5/22/2014 92 0 8 See More See Less