Summary Adult Limb Deformity is a lower extremity condition that can result from childhood growth impairment, metabolic bone disorders, severe osteoarthritis, trauma, or fracture malunion/nonunion. Diagnosis is made with a combination of clinical examination and plain full limb length radiographs. Treatment is usually osteotomy of the femur and/or tibia, although arthroplasty may also correct deformity in appropriate patients. Epidemiology Incidence varies depending on the underlying cause of the deformity Demographics no gender predilection age younger patients more likely due to trauma/childhood growth abnormalities Location upper extremity - rare deformity is commonly seen at elbow and wrist secondary to fracture malreduction lower extremity (focus of this topic) femur vs. tibia or both location of deformity helps determine where correction should be made proximal vs. distal Risk factors family history trauma Etiology Pathophysiology mechanism of injury related to associated injury or orthopedic condition that contributes to bony limb deformity pathoanatomy in most cases, the anatomic axis of bone is altered for some reason (malunion/nonunion, metabolic bone disease, etc) to the point where there is significant mechanical axis deviation (MAD), leading to altered joint contact pressures and ligamentous stability, which further contributes to joint degeneration and worsening of mechanical alignment over time Associated conditions orthopaedic conditions malunion nonunion previous osteotomies genu valgum/genu varum advanced arthritis with deformity bony tumors childhood abnormalities blount's disease focal fibrocartilaginous dysplasia proximal tibial physeal injury cozen's phenomenon skeletal dysplasia spondyloepiphyseal dysplasia (SED) metaphyseal dysplasia (MED) femoral anteversion limb length discrepancy (LLD) medical conditions metabolic bone disorders renal osteodystrophy rickets vitamin D deficient hypophosphatemic rickets osteogenesis imperfecta neuromuscular disorders cerebral palsy neurofibromatosis Anatomy Osteology femur normal proximal femur neck shaft-angle 130 +/- 7º normal proximal femur anteversion 10 +/- 7º tip of greater trochanter should be at the level of the center of femoral head and is used as the start point for measuring the anatomic axis of the femur (AAF) difference between anatomic and mechanical femoral axes is normally 5-7º tibia shaft is triangular in cross-section tibial tubercle sits anterolaterally and attaches to patellar tendon anatomic and mechanical tibial axes should be equal if no deformity exists Ligaments knee medial collateral ligament (MCL) - superficial MCL (sMCL) and deep MCL (dMCL) sMCL attaches just posterior to medial epicondyle on femur and 6 cm distal to joint line on tibia dMCL attaches has meniscofemoral and meniscotibial attachment sites lateral collateral ligament (LCL) attaches posterior to lateral epicondyle on femur and anteriorly on fibular head both LCL and MCL contribute to coronal plate stability and can complicate deformity abnormal joint line congruence angle JLCA (>2º) is indicative of soft tissue laxity around the joint Classification Descriptive based on bone(s) affected, position (varus/valgus, procurvatum/recurvatum, etc.) and degree of deformity Presentation History prior trauma or childhood deformity/bone disease with/without progression Symptoms common symptoms pain with location based on deformity varus deformity = medial knee pain valgus deformity = lateral knee pain subtle to obvious deformity complaints of abnormal gait or loss of function Physical exam inspection note coronal/sagittal plane deformity note any rotational deformity femoral anteversion - increased IR >70º residual increased external tibial torsion limb-length discrepancy motion range of motion (ROM) at the hip, knee and ankle should be evaluated ligamentous laxity should be evaluated Imaging Radiographs recommended views weight-bearing AP & lateral full-length lower extremity views patellas should be facing directly anterior for correct rotational profile x-ray tube should be placed 10 ft away from cassette at the level of the knees weight-bearing AP & lateral views of each affected limb segment findings anatomic axis - measured on each anatomic segment femur (AAF) bisects medullary canal of femur measured from tip of greater trochanter distally to knee typically exits just medial to midpoint of distal femur tibia (AAT) bisects medullary canal of tibia measured from center of proximal tibia to distal tibia mechanical axis limb line from center of femoral head to center of ankle femur (MAF) line from center of femoral head to center of distal femur tibia (MAT) line from center of proximal tibia to center of ankle should be same as AAT if there are no deformities of tibia joint line axes femur line connecting the distal aspects of the medial/lateral femoral condyles tibia line connecting the proximal aspects of the medial/lateral tibial plateau measurements coronal plane anatomic/mechanical angle relationship between anatomic and mechanical angles femur: 5-7º tibia: AAT = MAT in most cases mechanical axis deviation (MAD) occurs when mechanical limb axis does not pass through center of knee MAD lateral to center of knee = valgus alignment MAD medial to center of knee = varus alignment anatomic axis measurements - denoted with lowercase 'a' femur medial proximal femoral angle (aMPFA) - normal: 84º (80-89º) lateral distal femoral angle (aLDFA) - normal: 81º (79-83º) tibia medial proximal tibial angle (MPTA) - normal: 87º (85-90º) lateral distal tibial angle (aLDTA) - normal: 89º (86-92º) mechanical axis measurements - denoted with lowercase 'm' femur lateral proximal femoral angle (mLPFA) - normal: 90º (85-90º) lateral distal femoral angle (mLDFA) - normal: 87º (85-90º) tibia medial proximal tibial angle (MPTA) - normal: 87º (85-90º) lateral distal tibial angle (mLDTA) - normal: 89º (86-92º) joint line convergence angle (JLCA) JLCA of femur and tibia should be essentially parallel normal = within 0-2º of each other sagittal plane measurements posterior distal femoral angle (PDFA) - normal range: 79-83º posterior proximal tibial angle (PPTA) - normal range: 77-84º leg length discrepancy (LLD) difference between distance from top of femoral head to center of ankle joint on each limb can measure femur and tibia separately to determine source of structural LLD deformity calculation center of rotation and angulation (CORA) is the intersection of proximal and distal mechanical axes of a deformed bone when the deformity is solely angular if the deformity is a combination of angulation and translation, the CORA will move from the site of mechanical axis intersection criteria dictating treatment abnormal values help determine the site of deformity and site/degree of correction needed coronal vs. sagittal plane femur vs. tibia or both proximal vs. distal deformity closer to joint will have greater effect on angulation at that joint CT indications rotational malalignment views axial, sagittal, coronal sequences findings axial cuts particularly helpful for establishing femoral version and axial malalignment Treatment Overview angulation, translation, length, and rotation should be evaluated and corrected in that order Nonoperative bracing/orthoses indications subtle deformity within limits of radiographic parameters listed above deformity with minimal functional deficit unable to undergo surgical intervention modalities dependent on etiology of deformity bracing orthoses (knee-ankle foot) outcomes bracing is often not well tolerated minimal data exists to demonstrate risk of deformity progression with nonoperative management Operative osteotomy derotational femoral osteotomy indications no absolute indications relative indications excessive femoral anteversion, < 10º of external rotation patellar maltracking and instability caused by increased femoral internal rotation gait disturbance with difficulty running techniques proximal intertrochanteric vs diaphyseal vs. distal supracondylar location blade plate vs. locking plate vs. intramedulllary nail for fixation outcomes all forms of derotational osteotomies appear to show improved outcomes ideal degree of version correction remains debated may have undesired impact on coronal plane alignment valgus-producing tibial osteotomy indications varus MAD with MPTA < 85º and CORA located within tibia, indicating that tibia is cause of varus malalignment no clinical or radiographic evidence of arthritis in other two compartments usually performed in younger patients that are not good candidates for total knee arthroplasty (TKA) or who have larger tibial deformity not amenable to treatment with primary TKA techniques medial opening wedge tibial osteotomy lateral closing wedge tibial osteotomy outcomes significant improvements in MAD and outcome scores (Lysholm, SF-36,VAS) 90-95% excellent results at 5 years, decreased to 50-70% at 10 years higher failure rates in smokers, age>60, and concomitant arthritis in other two compartments valgus-producing femoral osteotomy indications varus MAD with increased mLDFA (>90º) or aLDFA (>83º) and CORA located within the femur, indicating femoral contribution to varus malalignment joint line obliquity after valgus-producing tibial osteotomy if deformity in both tibia and femur techniques lateral closing wedge osteotomy outcomes improvements in MAD and outcome scores varus-producing femoral osteotomy indications valgus MAD with decreased mLDFA (<85º) or aLDFA (<79º) valgus deformity >12º clinical and radiographic evidence of no medial compartment arthritis relative indications may help improve patellar tracking in cases of genu valgum with increased Q angle may be useful in cases of MCL stress due to valgus alignment techniques lateral distal femoral opening wedge osteotomy medial distal femoral closing wedge osteotomy outcomes safe, reproducible and effective at normalizing valgus malalignment gradual limb lengthening (LLD) indications >2 cm LLD compared to contralateral side, although specific degree of LLD is not absolute indication/contraindication techniques external fixator intramedullary device +/- external fixator outcomes significantly improved LLD to <1 cm deficit also has the ability to concomitantly correct a small degree of angular deformity, particularly in diaphyseal or metaphyseal location total knee arthroplasty (TKA) indications deformity about the knee joint in setting of multi-compartmental arthritic changes techniques primary TKA with normal implants primary TKA with stemmed implants consider in cases with ligamentous laxity or after osteotomy that compromises collateral integrity TKA after extra-articular osteotomy outcomes consistent improvement in outcome scores able to correct coronal alignment to within several degrees of neutral easier with CORA further from joint more complicated and results less reliable after extra-articular osteotomy Techniques Bracing/orthoses (KAFO) technique consists of an AFO with metal uprights, a mechanical knee joint and two thigh bands Derotational femoral osteotomy approach lateral approach to femur or medial femur subvastus approach depending on technique used technique proximal osteotomy intertrochanteric or subtrochanteric osteotomy performed fixed with blade plate or locking plate also able to correct flexion/extension and varus/valgus deformity diaphyseal osteotomy w/ intramedullary fixation small stab incision laterally over femoral isthmus drill holes used to begin osteotomy intramedullary nail inserted proximally at greater trochanter once nail is passed to level of fracture site, osteotomy can be completed femur is then derotated to 45º of external rotation and 45º of internal rotation with patella in line/slightly externally rotated relative to the ASIS distal supracondylar osteotomy medial subvastus approach schanz pins inserted in proximal and distal segments followed by osteotomy once segment derotated, supracondylar locking plate placed complications under correction over correction causing retroversion and out-toeing rare Valgus producing tibial osteotomy approach lateral closing wedge osteotomy anterolateral medial opening wedge osteotomy anteromedial technique lateral closing wedge osteotomy resect anterior aspect of fibular head osteotomy performed proximal to tuberosity under fluoroscopy wedge removed laterally, with intact medial cortex acting as hinge fixation with staples or plate medial opening wedge osteotomy biplanar alignment guide used place hinge pin from medial to lateral, exiting just below lateral tibial plateau cutting guide placed, patellar tendon protected osteotomy created and packed with bone wedge complications nonunion patellar tendon injury patella baja alterations in tibial slope increases after opening wedge more likely decreases after closing wedge more likely Valgus producing femoral osteotomy approach lateral subvastus approach to distal femur technique lateral closing wedge femoral osteotomy k-wires inserted from laterally at supracondylar femur directed distally aimed at the far medial cortex just proximal to the medial femoral condyle hinge through medial cortex without perforating intact medial cortex provides higher axial/rotational stability after osteotomy closure of wedge with gentle valgus force biplanar vs. uniplanar osteotomy complications nonunion medial hinge fracture Varus producing femoral osteotomy approach lateral opening wedge femoral osteotomy lateral subvastus approach to distal femur medial closing wedge femoral osteotomy medial subvastus approach to distal femur technique lateral opening wedge femoral osteotomy k-wires inserted from lateral to medial at supracondylar femur leave 1-2cm medial cortical hinge spread osteotomy open and place premeasured spacer followed by lateral femoral plate medial closing wedge femoral osteotomy osteotomy site is at metaphyseal-diaphyseal junction medial distal femoral locking plate after closure complications quadriceps tendon injury intercondylar femur fracture if osteotomy too distal lateral hinge fracture less stability of osteotomy after fixation Gradual limb lengthening approach lateral hip approach for intramedullary nailing vs. external fixation technique distraction osteogenesis wait 5-7 days to begin distraction then distract at about 1 mm/day external fixator uniplanar vs. circular/hexapod frame intramedullary device +/- external fixator insertion of intramedullary device to isthmus followed by osteotomy and completion of intramedullary nailing can add external fixator for improved multiplanar stability if also trying to correct angular deformity new intramedullary nails allow controlled lengthening complications external fixator pin site infection scarring poor cosmesis intramedullary lengthening poor regenerate bone formation joint contracture/dislocation nail failure TKA approach standard medial parapatellar technique goal is to restore neutral mechanical alignment with bone cuts of distal femur and proximal tibia valgus cut angle of distal femur from 4-7º based on stature and femur length intramedullary guide based on AAF AAT usually equal to MAT so intramedullary/extramedullary guides usually provide equivalent resection with extra-articular malalignment, same rules of normal limb deformity assessment apply locate CORA on tibia, femur or both as CORA moves further from knee joint, correction ability with distal femur and proximal tibia bone cuts lessens more severe deformity or deformity closer to the joint may require corrective extra-articular osteotomy in addition to TKA applies in both coronal and sagittal planes corrective osteotomy better tolerated on tibia if necessary, as this equally alters flexion/extension gap important to understand location of osteotomy, as this may affect collateral stability if collateral stability compromised by ostetotomy, implant constraint should be increased complications periprosthetic infection ligamentous contractures/laxity patellar tendon injury Complications Deformity undercorrection/overcorrection unfavorable loading on one compartment preoperative planning important to avoid this opening wedge osteotomy may be at higher risk because it can lose some correction over time Nonunion reported rates around 5% risk factors smoking older age > 60 obesity far cortex hinge fracture Ligamentous/tendon damage quadriceps tendon more at risk in femoral osteotomies patellar tendon at risk in tibial osteotomies Patella baja caused by proximal tibia osteotomies supra-tubercle osteotomy increases risk compared to infra-tubercle may cause increased knee pain and difficulty with future TKA Infection 1-4% incidence increases risk of nonunion risk factors smoking admission to hospital vs. outpatient surgery center Prognosis Within first 5 years, radiographic and clinical outcomes remain excellent in >90% of patients. After >10 years, this drops to around 50-70% 15-25% end up requiring TKA within 10 years risk factors for poorer outcomes prior failed arthroscopic treatment obesity age > 60 insufficient correction