Sports Flashcards
Imaging for patellar instability?
-
Anatomy
- Passive stability
- medial patellofemoral ligament (MPFL) is primary restraint in first 20 degrees of knee flexion
- usually avulses from medial epicondyle of femur
- patellar-femoral bony structures account for stability in deeper knee flexion
- Dynamic stability
- vastus medialis (attaches to MPFL)
- Passive stability
-
Radiographs - AP, lateral, skyline, oblique
- rule out fracture or loose body
- medial patellar facet (most common)
- lateral femoral condyle (usually occurs when patella is reduced)
- AP views
- best to evaluate overall lower extremity alignment and version
- lateral views
- best to assess for trochlear dysplasia
- Trochlea >145 = dysplasia
- Crossover sign = dysplasia = trochlea crrosses the supracondylar prominence
- Evaluate for patellar height (patella alta vs baja)
- Blumensatts line should be inferior to patella
- Insall-Salvati method
- Blackburne-Peel method
- Caton-Deschamps
- Plateau-Patella Angle (20-30 deg)
- axial views
- best assess for lateral patellar tilt
- lateral patellofemoral angle
- rule out fracture or loose body
-
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
- CT
- TT-TG > 20 shows excessive varus
- Torsional assessment
- Assess trochlear anatomy
- TT-TG > 20 shows excessive varus
You are concerned about patellar tendon rupture. Give 4 ways to assess patellar height
- Blumensatts line should be inferior to patella
-
Insall-Salvati method
- length patella/length tendon = 1
-
Blackburne-Peel method
- length articular surface/distance from line drawn parallel to tibial plateau = 0.8
-
Caton-Deschamps
- length articular surface/distance to tibial plateau = 1.0
-
Plateau-Patella Angle (20-30 deg)
- line drawn along tibial plateau, then line drawn from posterior plateau to inferior patella
Treatment options for patellar instability?
-
NSAIDS, activity modification, and physical therapy
-
indications
- mainstay of treatment for first time patellar dislocation
- 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
- VMO strengthening
- core strengthening of hip abductors, gluteals, and abdominals
- patellar stabilizing sleeve or “J” brace
- consider knee aspiration for tense effusion
- positive fat globules indicates fracture
-
indications
-
Operatvie Approach
- Address all deformities (Osseous, static, dynamic)
- Options for Osseus
- Dysplasia - groove deepening
- TT-TG or patella alta - tibia osteotomy
- Static
- MPFL reconstruction
- Not all need to be addressed; sometimes an osteotomy with MPFL reconstruction will comprensatate for trochlear dysplasa
-
arthroscopic debridement vs ORIF
- indications
- displaced osteochondral fractures or loose bodies
- chronic patellofemoral instability
- techniques
- arthroscopic vs open
- indications
-
MPFL repair
- indications
- acute first time dislocation
- techniques
- direct repair when surgery can be done within first few days
- no clinical studies support this over nonoperative treatment
- indications
-
MPFL reconstruction with autograft vs allograft
- Has good outcomes and can improve stability even with associated boney abnormalities, however the ideal situation is below
- TT-TG <20
- Caton-dechamps < 1.2
- Apprehension at 30 deg of flexion
- Grade A trochlear dysplasia
- indications
- recurrent instability (>2)
- Has good outcomes and can improve stability even with associated boney abnormalities, however the ideal situation is below
-
medial tibial tubercle transfer
- Indications
- may be used in addition to MPFL or in isolation for significant malignment
- TT-TG >20mm on CT
- Techniques
- anteromedialized displacement of osteotomy and fixation
- correct TT-TG to 10-15mm (never less than 10mm)
- Indications
-
lateral release
- islolated release no longer indicated for instability
- only indicated if there is excessive lateral tilt or tighness after medialization
- To help offload the patella in times of painful PF syndrome refractory to PT
- technique
- arthroscopic
-
trochleoplasty
- Poor outcomes with high rates of OA and limited improvement in pain (despite some reports of improved outcomes)
- Indications
- rarely addressed (in the USA) even if trochlear dysplasia present
- may consider in severe or revision cases
- May consider if there is no other pathology
- *Contra-indicated if there is evidence of arthritis
- Often patients will get increased pain post-op, even though risk of dislocation is dramatically reduced
- techniques
- arthroscopic or open trochlear deepening procedure
-
osteochondral defect repair
- indications
- large osteochondral loose body
- techniques
- primary repair vs allograft depending on size
- indications
Complications associated with patellar instability
<!--StartFragment-->
-
Recurrent dislocation
- redislocation rates of 15-44% have directed interest more towards surgical treatment
-
Medial patellar dislocation and medial patellofemoral arthritis
- almost exclusively iatrogenic as a result of prior patellar stabilization surgery
<!--EndFragment-->
Where is Schottle’s point
- 1 mm anterior to the posterior cortex extension line
- 2.5 mm distal to the posterior origin of the medial femoral condyle
- proximal to the level of the posterior point of the Blumensaat line
- on a lateral radiograph with both posterior condyles projected in the same plane
Ideal situation and indications for MPFL repair
-
Ideal situation
- TT-TG <20
- Caton-dechamps < 1.2
- Apprehension at 30 deg of flexion
- Grade A trochlear dysplasia
-
indications
- recurrent instability (>2)
Doesn’t mean that it can’t be done with boney abnormalities, but it just makes it less likely to suceed
Types of muscle contractions
<!--StartFragment-->
- **Isotonic **
- Force remains constant through range of motion
- improves motor performance
- Biceps curls using free weights
- **Isometric **
- Constant muscle length and tension that is proportional to the external load
- Causes muscle hypertrophy
- Pushing against an immovable object
- **Concentric **
- Shortened muscle and tension that is proportional to the external load
- Biceps curl with elbow flexing
-
Eccentric<!--StartFragment-->
- Force remains constant as muscle lengthens.
- Most efficient method of strengthening muscle
- Biceps curl with elbow extending
- **Isokinetic **
- Muscle contracts at a constant velocity or constant external load.
- often used to objectively evaluate muscle strength during injury rehabilitation.
- Require special machines (e.g, Cybex).
-
Plyometric
- Rapid eccentric-concentric shortening
- Good training for sports the require power
- Box jumps
-
Open chain
- Distal end of extremity moves freely
- Seated leg extensions and curls
- **Closed chain **
- Distal end of extremity is fixed
- Squats with planted foot
<!--EndFragment-->
How does dynamic exercise training improve cardiac output?
increasing stroke volume
Changes that occue during aerobic training
<!--StartFragment-->
-
contractile muscle adapts by increasing energy efficiency
- increases in mitochondrial size, number, and density
- increases in enzymes involved in Krebs cycle, fatty acid processing, and respiratory chain
- over time, increased use of f_atty acids > glycogen_
- over time, oxidative capacity of Type I, IIA, and IIB fibers increase
- percentage of more highly oxygenated IIA fibers increases
- Aerobic Threshold: level of effort at which anaerobic energy pathways become significant energy producer
- Anaerobic (lactate) Threshold: level of effort at which lactate production > lactate removal
<!--EndFragment-->
How does is strength training assoicated with strength gains?
<!--StartFragment-->
- typically high-load, low-repetition activities
- results in increased cross-sectional area of muscle due to muscle hypertrophy
- hyperplasia (increased number of fibers) less likely
- results in increased motor unit recruitment +/- improved synchronization of muscule activity
- maximal force production is proportional to muscle physiologic cross-sectional area
<!--EndFragment-->
how does weight traing change muscle composition
<!--StartFragment-->
-
Effects on muscles
- increased cross-sectional area
- increased strength
- increased mitochondria
- increased capillary density
- thickened connective tissue
- Adult strength gains are associated with muscle hypertrophy
- Adolescent strength gains occur more from increased muscle firing efficiency and coordination
<!--EndFragment-->
What are 4 kinds of muscle injury?
<!--StartFragment-->
-
Muscles soreness
- caused by edema and inflammation in the connective tissue
- leads to increased intramuscular pressure
- occurs primarily in Type IIB fibers
- worse with unaccustomed eccentric exercise
- often with delayed onset: _Delayed-Onset Muscle Soreness (DOMS) _
- peaks at 24-72 hours
- elevated CK levels seen in serum
- caused by edema and inflammation in the connective tissue
-
Muscles strain
- occurs commonly at myotendinous junction (off during eccentric contraction which produces highest forces in skeletal muscle)
- pathoanatomy in inflammation followed by fibrosis
-
Muscle contusion
- non-penetrating blunt injury
- leads to hematoma and inflammation
- extracellular connective tissue forms within 2 days, peaks between 5-21 days
- healing characterized by late scar formation, variable muscle regeneration
- myositis ossificans (bone formation within the muscle tissue)
- most apparent 4 weeks post-injury
-
Muscle laceration (complete tear)
- typically occur near myotendinous junction
- characterized by abnormal muscle countour
- fragments heal by dense connective scar tissue
- this process is mediated by myofibroblasts
- TGF-Beta stimulates differentiation and proliferation of myofibroblasts
- regeneration and renervation: unpredictable and likely incomplete
<!--EndFragment-->
Treatment of muscle injury
<!--StartFragment-->
-
Goals of treatment
- decrease inflammation
- increase local blood flow
- increase tissue compliance
-
Modalities include
- cryo or heat treatments
- massage
- ultrasound
- electrical stimulation
- Iontophoresis
- use of an electrical current to drive charged molecules of medicine through the skin to the deep tissues
- medications including steroids, local anesthetics, salicylates, and non-steroidal anti-inflammatory drugs
<!--EndFragment-->
Approach to chondral defect in the knee
- <2 = drilling
- 2-4 = mosaiplasty
- >4 = allograft
- not enough donor to fill in the defect
- becomes too irregular
- HTO
- If it’s more degenerative
- Or to augment any procedure
- Always look at your alignment
- ACI
- Not used in Canada
- Cost – 25K
- Similar outcomes to microfracture
- Allograft
- Fresh, matched
- Preserved, not frozen
- Needs to be implanted with-in 21 days
- 15K
Risk factors for patellar instability
- ligamentous laxity (Ehlers-Danlos syndrome)
- dysplastic vastus medialis oblique (VMO) muscle
- lateral displacement of patella
- 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
- increased quadriceps angle (Q angle)
- average for women 15 degrees
- average for men 10 degrees
- previous patellar instability event
- “miserable malalignment syndrome”
- femoral anteversion
- genu valgum
- external tibial torsion / pronated feet
Pertient physical exam findings of patellar instablity
- 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
- <1cm at 30 deg of flexion
- patellar 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
Technique for MPFL Repair
- Diagnostic arthroscopy
- ST is harvested
- the graft is prepare with sutures at both ends
- Superomedial patella is exposed, two drill holes are made
- femoral origin can be reliably found radiographically (Schottle point)
- check isometry of the graft
- Drill your hole
- Secure the graft with an interference screw in the femur
- Be careful not to overtension the graft if there is trochlear dysplasia
- Controversial where to tighten the graft
- pull the graft threw the drill holes in the patella and sutured onto themselves
Differential diagnosis for painful cartilage lesion in the knee
-
Secondary osteonecrosis
- older woman
- think risk of AVN
-
Spontaneous osteonecrsis of the knee
- middle age female
- releived by arthroscopy
-
Osteochondritis dissecans (OCD)
- more commonly found at _lateral aspect of medial femoral condyl_e of 15 to 20-year-old males
-
Transient osteoporosis
- more common in young to middle-aged men
- multiple joint involvement found in 40% of patients (transient migratory osteoporosis)
-
Occult fractures and bone bruises
- associated with trauma, weak bones, or overuse
What is the outerbridge classification
Grade 0: Normal cartilage
I: Softening and swelling
II: Partial thickness defect, fissures < 1.5cm diameter
III: Fissures down to subchondral bone, diameter > 1.5cm
IV: Exposed subchondral bone
Factors that will affect your decision making in articular cartilage defect
-
patient factors
- age
- skeletal maturity
- low vs. high demand activities
- ability to tolerate extended rehabilitation
-
defect factors
- size of defect
- location
- contained vs. uncontained
- presence or absence of subchondral bone involvement
Surgical options to address cartilage lesions in the knee
-
Address concominant injuries
- Soft tissue
- Meniscus
- Meniscetomy is a relative contraindication to cartilage salvage procedures
- Young patients may warrant a meniscal transplant
- Cruciate deficiency
- MFPL or patellar stabilization
- Meniscus
- Boney (unloading or alignment)
- High tibial osteotomy
- Tibial tubercle osteotomy
- Soft tissue
-
ORIF
- acute injury
- sufficient osseous portion
-
Microfracture <2X2
- can do retrograde if articular surface is intact
- single procedure
- does not address bone loss
- Best results
- <2X2cm
- contained
- acute
-
Moscaoplasty <2X2
- limited by irregular surface and harvest
- medial and lateral NWB trochlea
- cost effective, single stage
- requires 3 month NWB
-
ACI
- 2 stage, expensive
- requires contained defect
- comparable to microfracture
-
Allograft
- large, uncontained defect
- lots of processing, expensive, but works
For older patients can consider UKA, TKA
What are two patellar unloading procedures
-
Maquet (tibia tubercle anteriorization)
- indicated only for distal pole lesions
- only elevate 1 cm or else risk of skin necrosis
- contraindications
- superior patellar arthrosis (scope before you perform the surgery)
-
Fulkerson alignment surgery (tibia tubercle anteriorization and medialization)
- indications (controversial)
- lateral and distal pole lesions
- increased Q angle
- contraindications
- superior medial patellar arthrosis (scope before you perform the surgery)
- skeletal immaturity
- indications (controversial)
technique for allochondral graft for the knee
-
overview
- goal is to replace cartilage defect with live chondrocytes in mature matrix along with underlying bone
- fresh, refrigerated grafts are used which retain chondrocyte viability
- Max 28 days
- may be performed as a bulk graft (fixed with screws) or shell (dowels) grafts
-
technique
- match the size and radius of curvature of articular cartilage with donor tissue - based on the plain AP
- MRI can be used but will underestimate the size of the lesion
- Small subvastus can be used vs more extended medial or lateral parapatellar for improved exposure
- a recipient socket is drilled at the site of the defect
- an osteochondral dowel of the appropriate size is cored out of the donor
- Thinner is better to reduce amount of implanted bone
- the dowel is press-fit into place
-
Clinical pearls
- Lots of irrigation to reduce thermal injury
- Light impaction of the graft so you don’t injury the condrocytes
-
benefits
- include ability to address larger defects, can correct significant bone loss, useful in revision of other techniques
-
limitations
- limited availability and high cost of donor tissue
- live allograft tissue carries potential risk of infection
-
Post-op
- Avoid shear or compressive stress for 6 weeks
- Limited WB
- Full ROM
- Brace is controversial
- 6-12 weeks
- ADL, progress strength
- 3 months
- Strength, core, proprioceptive with gradual return to sports
- Avoid impact activities (6-12months)
Options for cartilage regeneration
-
Chondrocytes
- ACI: autologous chondrocyte implantation
- chondrocytes harvested from non-wt bearing surface & expanded ex-vivo
- in separate procedure, periosteal flap harvested and sewn over defect; chondrocytes in collagen suspension are squirted underneath & sealed with fibrin
- problem → does not regenerate hyaline cartilage
-
Pluripotent Stem Cells
- embryonic stem cells (ESC) & induced pluripotent stem cells (iPSC)
- may lead to the development of tumor; teratoma formation in vivo is well recognized
- no current studies underway
-
Mesenchymal Stem Cells
- ability to differentiate along various cell lineages, including chondrocytes, adipocytes, osteoblasts, and myocytes
- ideal option for cartilage regeneration because they represent a readily available and accessible supply of cells, and they have the capacity for considerable expansion and differentiation
- TGFβ & BMPs used to induce chondrogenesis
- bone marrow stem cells (BMSC) have been used in some studies with promising results
What are the main factors stimulating cartilage growth
TGFβ family, including BMP-2 & BMP-7
chondrogenic differentiation
stimulating production of cartilage ECM
Others:
FGF, IGF-1, PDGF, and, of course, PRP!
What predisposes females to ACL tears
Neuromuscluar, quads dominant
Landing biomechanics - higher valgus, more extension (see below)
Smaller notches
Smaller ligaments
Hormone levels (arises at puberty, poor understanding)
Valgus leg alignment
Higher tibial slope
Anatomy of the ACL
- 85% of anterior stability
- 1100N to tear
- 90% type 1 collagen
- Secondary restraint to rotation
- Anatomy
- 33X11mm
- LFC
- Anterior to PCL, at level of anterior horn of lateral meniscus
- Bundles
- Anteromedial - isometric
- Posteriolateral - tight in extension, contributes to rotational stability
- Blood supply - middle geniculate artery
- Innervation - posterior articular nerve (from tibial nerve)
Injuries associated with ACL tear
- Often associated with a meniscal tear
- lateral meniscal tears in up to 50% of acute ACL tears
- Bone bruising (50%)
- LFC in sulcus terminalis
- Posterior tib plateau
- Chronic ACL deficient knees associated with
- chondral injuries
- complex unrepairable meniscal tears
- medial meniscal tears
- relation with arthritis is controversial
what degree of slope is at risk for ACL tear
>12 deg
What are key factors to include in an acl prevention program
- 30 min, 3 times/wk for approximately 8 wk
- Preseason implementation for neuromuscular adaptation
- Perform as a warm-up to avoid neuromuscular fatigue
- Maintenance recommended to avoid deconditioning, which can occur at 2 to 8 wk
- Must include neuromuscular and proprioceptive training, plyometrics, agility drills, func-tional balance, and core strengthening
- Low cost and easy to implement
- Identify at-risk players who need more intensive intervention (eg, drop vertical test)
- Encourage compliance (eg, varied workouts, correlate training with improved sport/ muscular performance, risk awareness education/training)