summary Leg Length Discrepancy is a common condition that may be caused by a congenital defect, disruption of the physis, or a paralytic disorder and presents with limb length asymmetry of varying magnitude. Diagnosis is made with block testing and radiographic scanography. CT studies can be used to calculate LLD in the presence of contractures. Treatment is observation with or without shoe lifts for differences < 2 cm at skeletal maturity. Surgical intervention is indicated for differences > 2 cm, with different techniques depending on the discrepancy magnitude and remaining skeletal growth. Epidemiology Incidence 2cm LLD occurs in up to 2/3 of the population Etiology Common causes of LLD congenital disorders hemihypertrophy dysplasias PFFD DDH unilateral clubfoot paralytic disorders spasticity (cerebral palsy) polio physis disruption infection trauma tumor Associated conditions back pain increased prevalence of back pain osteoarthritis decreased coverage of femoral head on long leg side leads to osteoarthritis 84% of the time functional scoliosis inefficient gait equinus contracture of ankle Classification Static malunion of femur or tibia Progressive physeal growth arrest congenital absolute discrepancy increases proportion stats the same Presentation Symptoms usually asymptomatic Physical exam block testing with the patient standing, add blocks under the short leg until the pelvis is level, then measure the blocks to determine the discrepancy block testing is considered the best initial screening method tape measurement measure from the anterior superior iliac spine to the medial malleolus with a tape measure evaluate for hip, knee and ankle contractures affect apparent limb length hip adduction contracture causes apparent shortening of adducted side Imaging Radiographs teleoroentgenography (scanography) measure discrepancy with single exposure from 2m away bone age hand films determine bone age with bone age xray (hand) CT Scanography CT scanography is the most accurate diagnostic test with contractures of the hip, knee, or ankle LLD Projections General assumptions growth continues until 16 yrs in boys and until 14 yrs in girls Methods to project LLD at maturity Mosley graph estimation technique leg grows 23 mm/year, with most of that coming from the knee (15 mm/yr) proximal femur - 3 mm / yr (1/8 in) distal femur - 9 mm / yr (3/8 in) proximal tibia - 6 mm / yr (1/4 in) distal tibia - 5 mm / yr (3/16 in) Can be tracked with Green-Anderson tables uses extremity length for a given age Moseley straight line graph improves on Green-Anderson method by reformatting data in a graph form accounts for differences between skeletal and chronologic age minimizes error averages serial measurements Multiplier method prediction based on multiplying the current discrepancy by a sex and age specific factor most accurate for congenital LLD 1/2 of final leg length girls at age 3 boys at age 4 Treatment Nonoperative shoe lift or observation only indications < 2 cm projected LLD at maturity outcomes not associated with scoliosis or back pain Operative shortening of long side via epiphysiodesis of femur, tibia, or both indications 2-5 cm projected LLD limb lengthening of short side indications > 5 cm projected LLD lengthening often combined with a shortening procedure (epiphysiodesis, ostectomy) on long side physeal bar excision indications bony bridge involves <50% of physis at least 2 years left of growth amputation and prosthetic fitting indications non-reconstructable limb > 20 cmprojected LLD Techniques Distraction osteogenesis (Ilizarov principles) initiation perform osteotomy and place fixator metaphyseal corticotomy to preserve medullary canal and blood supply distraction wait 5-7 days then begin distraction distract ~ 1 mm/day following distraction keep fixator on for as many days as you lengthened concurrent procedures may lengthen over a nail so ex-fix can be removed sooner lengthening often combined with a shortening procedure (epiphysiodesis, ostectomy) on long side Complications Incomplete arrest/ angular deformity open technique percutaneous technique Pin site infections Fracture Delayed union Premature cessation of lengthening Persistent limb length discrepancy due to error in timing of surgery Joint subluxation/dislocation Mechanical axis deviation (MAD) lengthening along the anatomical axis of the femur leads to lateral MAD shortening along the anatomical axis of the femur leads to medial MAD
Technique Guide Technique guides are not considered high yield topics for orthopaedic standardized exams including ABOS, EBOT and RC. Growth Guided Hemiepiphysiodesis Lindsay Andras Paul D Choi Pediatrics - Hemihypertrophy
QUESTIONS 1 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 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 (SBQ13PE.73) A 12-year-old boy is evaluated for limb length inequality. He has a history of osteomyelitis of the left distal femur that was successfully treated. He is otherwise healthy with no other past medical history. Standing full length radiographs confirm a limb length discrepancy of 20 millimeters, attributable to differences in the lengths of the femora. Radiographs of the knee show complete closure of the left distal femoral physis with no angular deformity. If left untreated, what is the projected limb length discrepancy at maturity? QID: 5199 Type & Select Correct Answer 1 2 cm 3% (107/3463) 2 3 cm 3% (107/3463) 3 4 cm 19% (641/3463) 4 6 cm 73% (2516/3463) 5 10 cm 2% (67/3463) L 3 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic (OBQ13.107) A 12-year-old male patient is scheduled to undergo femoral lengthening. The 2 techniques at your disposal are (1) femoral lengthening along the mechanical axis of the limb with an external fixator, and (2) femoral lengthening along the anatomical axis of the femur with a telescoping nail. What happens to the mechanical axis of the limb when performing these techniques? QID: 4742 Type & Select Correct Answer 1 There is no mechanical axis deviation in (1), and medial mechanical axis deviation in (2). 31% (1558/5038) 2 There is lateral mechanical axis deviation in (1) and medial mechanical axis deviation in (2). 6% (324/5038) 3 There is no fixed direction of mechanical axis deviation in either technique. 10% (491/5038) 4 There is medial mechanical axis deviation in (1) and lateral mechanical axis deviation in (2). 6% (310/5038) 5 There is no mechanical axis deviation in (1), and lateral mechanical axis deviation in (2). 46% (2318/5038) L 4 Question Complexity B Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic 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 (OBQ12.29) At what age does longitudinal growth usually arrest in boys at the distal femur physeal growth plate? QID: 4389 Type & Select Correct Answer 1 18 9% (346/3744) 2 16 83% (3125/3744) 3 14 6% (214/3744) 4 12 1% (28/3744) 5 10 0% (8/3744) L 1 Question Complexity B Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ11.203) A 13-year-old boy presents with a leg-length discrepancy with the right leg shorter than the left. He has normal height for his age and his skeletal age is equal to his chronologic age. History and examination of Tanner staging reveals that he began puberty 1 month ago. His final leg length discrepancy at skeletal maturity is projected to be 4.0cm. Which of the following surgical options is the most appropriate? QID: 3626 Type & Select Correct Answer 1 Physeal stapling of the medial left tibial and femoral physis now with staged removal of staples at age 16 10% (336/3445) 2 Immediate lengthening of the right femur with ring external fixator 3% (89/3445) 3 Epiphysiodesis of the left femur 1 year after the onset of puberty 20% (705/3445) 4 Epiphysiodesis of the left femur and tibia 6 months from now 66% (2258/3445) 5 Epiphysiodesis of the bilateral femurs and shortening of the left tibia now 1% (27/3445) L 3 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ08.6) A 14-year-old boy sustains a significant distal femoral physeal fracture. Assuming that he has a complete growth arrest, what is the predicted leg length discrepency? QID: 392 Type & Select Correct Answer 1 1cm 4% (130/2965) 2 2cm 86% (2548/2965) 3 3cm 5% (141/2965) 4 4cm 3% (103/2965) 5 5cm 1% (32/2965) L 1 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic This is an AAOS Self Assessment Exam (SAE) question. Orthobullets was not involved in the editorial process and does not have the ability to alter the question. If you prefer to hide SAE questions, simply turn them off in your Learning Goals. (SAE07PE.19) An 8-year-old girl was treated for a Salter-Harris type I fracture of the right distal femur 2 years ago. Examination reveals symmetric knee flexion, extension, and frontal alignment compared to the contralateral knee. She has 1-cm of shortening of the right femur. History reveals that she has always been in the 50th percentile for height, and her skeletal age matches her chronologic age. Radiographs are shown in Figure 9. What is the expected consequence at maturity? QID: 6079 FIGURES: A Type & Select Correct Answer 1 7-cm limb-length discrepancy with the right femur longer 4% (19/485) 2 7-cm limb-length discrepancy with the left femur longer 90% (437/485) 3 12-degree varus deformity 2% (8/485) 4 18-degree valgus deformity 2% (12/485) 5 20-degree recurvatum deformity 1% (7/485) L 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic This is an AAOS Self Assessment Exam (SAE) question. Orthobullets was not involved in the editorial process and does not have the ability to alter the question. If you prefer to hide SAE questions, simply turn them off in your Learning Goals. (SAE07PE.81) A teenager is undergoing a correction of deformity and lengthening of the femur. Distractions are proceeding as expected; however, during his 6-week follow-up examination, the patient reports that the distraction motors have become harder to turn over for the past 2 to 3 days. Figures 37a and 37b show current radiographs. What is the most likely complication being encountered? QID: 6141 FIGURES: A B Type & Select Correct Answer 1 Incomplete corticotomy 7% (36/512) 2 Knee subluxation 1% (7/512) 3 Wire breakage 6% (31/512) 4 Poor regenerate bone formation 2% (8/512) 5 Premature consolidation 84% (429/512) L 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic This is an AAOS Self Assessment Exam (SAE) question. Orthobullets was not involved in the editorial process and does not have the ability to alter the question. If you prefer to hide SAE questions, simply turn them off in your Learning Goals. (SAE07PE.31) A 14-year-old boy undergoes application of a circular frame with tibial and fibular osteotomy for gradual limb lengthening. He initiates lengthening 7 days after surgery. During the first week of lengthening, he reports that turning of the distraction devices is becoming increasingly difficult. On the 9th day of lengthening, he is seen in the emergency department after feeling a pop in his leg and noting the acute onset of severe pain. What complication has most likely occurred? QID: 6091 Type & Select Correct Answer 1 Joint subluxation and acute ligament rupture 5% (37/679) 2 Incomplete corticotomy at the time of surgery with spontaneous completion and acute distraction 65% (438/679) 3 Premature consolidation of the osteotomy with breakage of bone transfixation wire 12% (83/679) 4 Fracture through the bone regenerate 9% (59/679) 5 Fracture of the tibia through a unicortical half-pin track 9% (58/679) L 3 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic This is an AAOS Self Assessment Exam (SAE) question. Orthobullets was not involved in the editorial process and does not have the ability to alter the question. If you prefer to hide SAE questions, simply turn them off in your Learning Goals. (SAE07PE.15) Which of the following is considered the best method to measure limb-length discrepancy in a patient with a knee flexion contracture? QID: 6075 Type & Select Correct Answer 1 Obtain a standard scanogram 9% (41/473) 2 Obtain a lateral CT scanogram 68% (321/473) 3 Measure the distance from the anterior superior iliac spine to the medial malleolus 10% (46/473) 4 Measure the distance from the umbilicus to the medial malleolus 3% (14/473) 5 Stand the patient on blocks to measure the difference in the heights of the iliac wings 10% (46/473) L 3 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic (OBQ07.255) A 9-year-old male sustains the fracture seen in Figure A. If a complete growth arrests occurs, his expected leg length discrepancy at skeletal maturity would be? QID: 916 FIGURES: A Type & Select Correct Answer 1 2 cm 2% (34/1855) 2 3 cm 3% (54/1855) 3 4 cm 7% (125/1855) 4 5 cm 11% (195/1855) 5 6 cm 78% (1442/1855) L 1 Question Complexity B Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic (OBQ06.108) A 14-year-old male patient with a leg-length discrepancy undergoes a distal femoral and proximal tibial epiphysiodesis on the longer leg. What is the anticipated amount of correction achieved with this procedure in this child? QID: 294 Type & Select Correct Answer 1 1.6 cm 4% (142/3250) 2 2 cm 7% (224/3250) 3 3.2 cm 82% (2656/3250) 4 4 cm 5% (166/3250) 5 6.4 cm 2% (49/3250) L 1 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic (OBQ05.159) A 9-year-old girl presents with a history of juvenile rheumatoid arthritis, and a 20 degree flexion contracture of her left knee. A clinical photo is shown in Figure A. Which of the following is the most accurate method of determining leg length discrepancy in this patient? QID: 1045 FIGURES: A Type & Select Correct Answer 1 Teloradiograph 5% (92/1787) 2 Orthoradiograph 14% (257/1787) 3 Scanogram 19% (345/1787) 4 CT scanogram 59% (1063/1787) 5 Bone scan 1% (18/1787) L 3 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic (SBQ04PE.39) A 17-year-old female presents for evaluation of a limb length discrepancy. While standing, a 10mm block is placed under her short leg resulting in a leveled pelvis. She has no lower extremity contractures. Which of the following next steps would be most appropriate following her initial screening? QID: 2224 Type & Select Correct Answer 1 Observation 81% (1423/1763) 2 Perform a CT scanogram 15% (267/1763) 3 Epiphysiodesis of the longer limb 1% (12/1763) 4 Femoral lengthening of the shorter limb 3% (49/1763) 5 Physeal bar excision 0% (1/1763) L 2 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic 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 (OBQ04.62) A 14-year-old boy has complete growth arrest of his left proximal tibia after a skateboarding injury. He currently has a 3mm leg-length discrepancy with left shorter than the right. A radiograph of the patients left hand, wrist, and fingers demonstrate a bone-age of 14 years. What is the most appropriate management of this patient? QID: 1167 Type & Select Correct Answer 1 Observation 65% (618/951) 2 Left tibial lengthening 2% (20/951) 3 Right tibia epiphysiodesis 26% (251/951) 4 Right femur epiphysiodesis 6% (53/951) 5 Amputation 0% (2/951) L 3 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic
All Videos (6) Podcasts (1) 30th Annual Baltimore Limb Deformity Course Incorporating the Multiplier Method into Your Pediatric Orthopedic Practice - John E. Herzenberg, MD John E. Herzenberg Pediatrics - Leg Length Discrepancy (LLD) 4/11/2022 351 views 5.0 (2) Bobby Menges Memorial HSS Limb Deformity Course 2020 Applications of the IM Lengthening Nail (ILN) in Limb Deformity: Discussion/Q&A Dan Prince Pediatrics - Leg Length Discrepancy (LLD) C 10/20/2020 610 views 3.0 (1) Bobby Menges Memorial HSS Limb Deformity Course 2020 Pre-op Planning for Tibia (ILN) - Mitchell Bernstein, MD, FRCSC Mitchell Bernstein Pediatrics - Leg Length Discrepancy (LLD) C 10/20/2020 692 views 3.0 (1) Pediatrics | Leg Length Discrepancy (LLD) Pediatrics - Leg Length Discrepancy (LLD) Listen Now 26:30 min 4/1/2020 691 plays 5.0 (1) See More See Less
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