O que você está sentindo¶
Uma fratura na extremidade inferior do fêmur, logo acima do joelho, causa dor exatamente no local da fratura. Inicialmente, a dor costuma ser aguda, passando depois para uma dor profunda e contínua. Ficar em pé, apoiar peso na perna, dobrar o joelho ou girar a perna pioram a dor; já o repouso, com a perna imóvel e bem sustentada, traz alívio.
Essa dor costuma piorar à noite e logo ao acordar; também pode pulsar após ficar muito tempo em pé. Até pequenos movimentos do joelho doem, pois a fratura ocorre justamente onde o fêmur se conecta à articulação do joelho. Algumas pessoas sentem que o joelho está instável, como se não conseguisse sustentá-las.
No dia a dia, a perna torna-se difícil de usar: caminhar por distâncias, subir escadas, levantar-se de uma cadeira baixa ou entrar no chuveiro tornam-se tarefas complicadas. Você pode precisar de muletas ou andador; carregar objetos enquanto caminha também se torna difícil. Dormir do lado afetado, dirigir e entrar/sair do carro também podem ser problemáticos.
Essa lesão é mais comum em idosos, especialmente mulheres acima de 60 anos, geralmente quando o osso já está enfraquecido. Em pessoas mais velhas, pode ser uma lesão grave: cerca de 1 em cada 4 pessoas acima da idade de aposentadoria com essa fratura não sobrevivem ao ano seguinte, e complicações médicas após a cirurgia são frequentes nessa faixa etária. Por isso, a cirurgia costuma ser recomendada: manter o osso imóvel permite que o paciente comece a se movimentar cedo, o que é essencial para sua saúde e independência.
A recuperação leva tempo. Mesmo com os tratamentos atuais, a perna pode não voltar totalmente ao normal em um ano; os efeitos da lesão na qualidade de vida podem persistir por até 12 meses. Com o tempo, a mobilidade do joelho e do quadril geralmente é restaurada.
O que está realmente acontecendo¶
O fêmur possui um corpo ósseo largo e uma extremidade inferior que se alarga, formando dois nódulos arredondados, um de cada lado do joelho. Esses nódulos constituem metade da articulação do joelho e são revestidos por cartilagem lisa, permitindo o deslizamento da articulação. Uma fratura do fêmur distal é a ruptura dessa extremidade inferior, logo acima do joelho. Quando o osso se quebra nesse ponto, as bordas irregulares da fratura e qualquer deslocamento da posição óssea são os responsáveis pela dor aguda e pela sensação de que o joelho não consegue sustentar o corpo.
A fratura também pode afetar o alinhamento do joelho. Esses dois nódulos precisam ficar na mesma altura para que o peso seja distribuído uniformemente pela articulação. Se a fratura fizer com que um dos lados desça ou que a superfície articular se desloque, o peso será suportado de forma desigual, acelerando o desgaste da cartilagem ao longo do tempo. O joelho também é mantido unido por ligamentos resistentes, que se fixam justamente na parte do osso que se quebrou; por isso, a articulação pode parecer instável até que o osso seja estabilizado.
Essa lesão é rara, representando cerca de 0,5% de todas as fraturas. É mais comum em idosos, especialmente mulheres, pois nessa faixa etária o osso costuma ser mais fino. Em pessoas mais jovens, geralmente é necessária uma força intensa, como em acidentes de carro ou quedas de altura, para provocar essa fratura. Em idosos, pode ocorrer até mesmo após uma simples queda sobre a perna.
Como o osso se quebra em vários fragmentos que se deslocam, raramente permanece estável por conta própria. Por isso, a cirurgia é geralmente indicada: o osso é mantido na posição correta com uma placa ou uma haste e parafusos, enquanto ocorre sua consolidação. Manter os fragmentos imóveis também permite o início precoce dos movimentos do joelho, o que ajuda a prevenir a rigidez articular. Os principais riscos dessa lesão são a falha na consolidação óssea ou a consolidação em posição inadequada; esses riscos aumentam quando a qualidade do osso é ruim.
O que podemos fazer a respeito¶
Antes de qualquer decisão, determinamos o padrão exato da fratura. Radiografias simples são o primeiro passo habitual. Às vezes, as radiografias são feitas sem que o paciente coloque peso na perna, pois isso permite visualizar a lesão sem risco de deslocamento ósseo adicional. A tomografia computadorizada, que gera imagens detalhadas a partir de radiografias, pode mostrar as linhas de fratura e qualquer deslocamento no joelho. Para fraturas complexas que atingem a superfície articular, uma reconstrução tridimensional por tomografia computadorizada auxilia no planejamento cirúrgico.
Para a maioria dos pacientes com essa fratura, o tratamento consiste em fixar o osso cirurgicamente. O objetivo é alinhar corretamente os fragmentos ósseos e mantê-los nessa posição até que o osso se consolide. Isso é feito com implantes metálicos, geralmente uma haste inserida no canal medular do fêmur ou uma placa com parafusos na face externa do osso. A escolha depende do padrão da fratura, da qualidade óssea e do estado do seu joelho. Quando a fratura rompe a pele, um fixador externo pode manter o osso estável enquanto os tecidos moles cicatrizam. Caso haja prótese de joelho ou quadril prévia, planejamos a fixação de modo que ela se fixe em osso saudável suficiente acima e abaixo da fratura.
Algumas fraturas são simples, com apenas uma fissura entre dois fragmentos. Nesses casos, um parafuso atravessando a fissura pode manter os fragmentos unidos, acelerando a consolidação óssea. Quando o osso se fragmenta em várias partes, às vezes é necessária uma segunda placa do outro lado do osso. Isso pode melhorar a mobilidade do joelho em 6 meses, reduzir complicações e diminuir a probabilidade de má consolidação óssea.
Se o osso não consolidar, pode ser necessária nova cirurgia. Isso pode envolver a adição de uma placa ao lado da haste já existente, às vezes com enxerto ósseo do próprio paciente para favorecer a cicatrização. A preservação do suprimento sanguíneo na região da fratura orienta como proceder nesses casos.
O que esperar¶
A maioria das fraturas na extremidade inferior do fêmur é tratada cirurgicamente; manter o osso imóvel permite que o paciente comece a se movimentar precocemente. Com os tratamentos atuais, a mobilidade do joelho e do quadril geralmente é recuperada com o tempo. Contudo, a recuperação é um processo demorado. Os efeitos dessa lesão na qualidade de vida podem durar até 12 meses; mesmo assim, a perna pode não voltar totalmente ao normal.
A cicatrização em si leva meses, não semanas. Nas fraturas do fêmur tratadas com uma haste inserida no centro do osso, a consolidação costuma ocorrer em cerca de 18 semanas; porém, algumas pessoas precisam de mais de 25 semanas. Caso a consolidação seja lenta ou não ocorra, outras cirurgias podem ajudar, e esse processo também leva meses.
Os principais problemas possíveis são a falha na consolidação do osso ou sua consolidação em posição inadequada. Esse risco é maior quando o osso é fino; em pessoas acima de 70 anos com fratura que atinge a articulação do joelho, quase 1 em cada 5 desenvolve não união óssea. Quando há prótese de joelho ou quadril próxima, cerca de 18% apresentam não união, e aproximadamente 1 em cada 4 tem alguma complicação. Se ocorrer infecção ou não união, isso pode se tornar uma condição crônica em quase um quarto dos pacientes afetados.
Deixar a fratura sem tratamento raramente é uma opção viável. Sem cirurgia, o osso dificilmente permanece no lugar por conta própria; além disso, ficar imóvel por semanas traz problemas próprios, razão pela qual a cirurgia costuma ser recomendada. Em idosos, essa lesão é grave: cerca de 1 em cada 4 pessoas acima da idade de aposentadoria não sobrevivem ao ano seguinte, e complicações médicas após a cirurgia são comuns nesse grupo etário.
O cenário real é o seguinte: com tratamento, a maioria das pessoas recupera a mobilidade do joelho e do quadril com o tempo; porém, a perna pode não parecer totalmente normal por até um ano. Algumas necessitam de novas cirurgias ao longo do processo. Seu cirurgião acompanhará a cicatrização por meio de radiografias e informará como o osso está se consolidando em cada avaliação.
Quando procurar ajuda médica¶
Essa lesão geralmente se manifesta de imediato. A dor é súbita e intensa, e a perna pode não suportar peso; por isso, a maioria das pessoas vai direto ao pronto-socorro. Procure o pronto-socorro se sofreu uma queda ou um golpe na coxa, se a dor é intensa, se a perna parece dobrada ou mais curta, ou se você não consegue ficar de pé sobre ela. Procure ajuda imediatamente se o osso quebrado perfurou a pele. Solicite avaliação por um especialista se já fez uma prótese de joelho ou de quadril e agora sente dor súbita logo acima do joelho, pois uma fratura próxima a uma prótese requer avaliação urgente. Em idosos, essa lesão é grave: cerca de 1 em cada 4 pessoas acima da idade de aposentadoria não sobrevivem por um ano; portanto, não espere para ver se a situação melhora por conta própria.
Evidence & references
This is the clinical evidence summary written for health professionals. It is technical, and it lists the research this page was built from. You do not need to read it to understand your treatment or to make a decision about it.
Anatomy & Pathophysiology¶
Bony Anatomy¶
- The bones of the knee are the distal femur, the proximal tibia, and the patella [1].
- The medial femoral condyle is larger and projects farther posteriorly and distally than the lateral condyle [4].
- The medial epicondyle is the most anterior and distal osseous prominence of the medial femoral condyle [4].
- The adductor tubercle is located proximal and posterior to the medial epicondyle [4].
- The gastrocnemius tubercle is located slightly distal and posterior to the adductor tubercle [4].
- The lateral femoral condyle projects farther anteriorly than the medial condyle [4].
- The lateral femoral condyle is wider in the medial-lateral direction than the medial femoral condyle [4].
- The sulcus terminalis is a small ridge on the lateral femoral condyle just distal to the intercondylar notch that separates the patellofemoral and tibiofemoral articular surfaces [4].
- The trochlear groove separates the femoral condyles anteriorly and constitutes the patellofemoral articulation [4].
- The intercondylar notch is of variable width and is the site of attachment of the cruciate ligaments [4].
- The tibial articular surface slopes 7° to 10° in the sagittal plane [4].
- The medial tibial plateau is larger than the lateral plateau and is concave in its frontal and sagittal planes [4].
- The lateral tibial plateau is smaller and more circular than the medial plateau, concave in the frontal plane, and convex in the sagittal plane [4].
- The medial and lateral tibial plateaus are separated by the intercondylar eminence and its medial and lateral spinous processes [4].
- The tibial tuberosity is the site of attachment of the patellar tendon and is typically located in the midline anteriorly but may be slightly lateral [4].
- Gerdy’s tubercle is the insertion site of the iliotibial band and is located 2 to 3 cm lateral to the tibial tubercle on the proximal tibia [4].
- The proximal fibula articulates with a facet of the lateral cortex of the tibia and is not part of the knee articulation [4].
- The patella is the largest sesamoid bone in the body and averages 2.5 cm in thickness [4].
- The patella has the thickest articular surface in the body, approximately 5 mm in the midportion and 2 mm on the sides [4].
- The patellar articular surface contains a vertical, central ridge that separates the broader lateral facet from the medial facet, and a smaller, more medial facet called the odd facet [4].
- The posterior slope of the medial tibial plateau is a mean of 10.7° and the lateral plateau is a mean of 7.2° [18].
- The fibular head is located a mean of 1.5 cm distal to the joint line, with a range of 6 to 32 mm [18].
- The medial femoral condyle has a large, convex articular surface [18].
- The lateral femoral condyle has a broader mean anterior-posterior dimension than the medial femoral condyle, which allows internal rotation of the distal femur with knee extension [18].
- The lateral femoral condyle has a broader mean medial-lateral dimension than the medial condyle [18].
- The lateral trochlear facet resists lateral subluxation of the patella [18].
- The sulcus terminalis is a transverse ridge extending from the oblique facets of the femoral trochlea that is deeper on the lateral condyle than on the medial condyle [18].
- The PCL inserts on the anteromedial wall of the intercondylar notch and the ACL inserts on the posterolateral wall [18].
- The patella has three facets: lateral, medial, and odd [18].
- The odd facet is a small facet on the distal medial patella that articulates in deep flexion of the knee [18].
Vascular and Nerve Anatomy¶
- The blood supply to the knee is formed from an anastomosis around the knee derived from the descending geniculate artery, medial and lateral superior geniculate arteries, medial and lateral inferior geniculate arteries, middle geniculate artery, and anterior tibial recurrent arteries [4].
- The middle geniculate artery supplies both the anterior and posterior cruciate ligaments [4].
- The inferior geniculate arteries pass deep to their respective collateral ligaments [4].
- The blood supply of the patella is derived from the geniculate artery complex with some contribution from the anterior tibial recurrent artery and primarily exists in the middle to inferior portions of the patella [4].
- The knee is innervated by branches of the femoral nerve (L2, L3, L4), obturator nerve (L2, L3, L4), and sciatic nerve (L4, L5, S1, S2) [4].
- The largest nerve providing innervation of the intra-articular knee is the posterior articular branch of the tibial nerve [4].
- The posterior articular branch of the tibial nerve supplies the infrapatellar fat pad, the synovial covering over the cruciate ligaments, and the periphery of the meniscus [4].
- Nerves to the cruciate ligaments contain vasomotor and pain fibers as well as mechanoreceptors that may be involved in proprioception [4].
- The infrapatellar branch of the saphenous nerve arises proximal to the knee joint medially and crosses distal to the patella to innervate the skin over the region of the anterior knee and proximal tibia [4].
- The popliteus artery travels through the adductor hiatus, where it is relatively immobile, and distally through the fibrous arch deep to the soleus muscle [24].
- The common peroneal nerve travels along the posterior edge of the biceps femoris and continues distally around the fibular neck [24].
- The tibial nerve, after branching from the sciatic nerve, courses distally through the center of the popliteus fossa [24].
Ligaments¶
- The anterior cruciate ligament (ACL) travels from the medial border of the lateral femoral condyle to its insertion site anterolateral to the medial tibial spine [1].
- The ACL prevents anterior translation and rotation of the tibia on the femur [1].
- The posterior cruciate ligament (PCL) prevents posterior subluxation of the tibia on the femur [1].
- The PCL runs from the lateral aspect of the medial femoral condyle to the posterior aspect of the tibia, just below the joint line [1].
- The medial collateral ligament has superficial and deep portions which stabilize the knee to valgus stresses [1].
- The lateral collateral or fibular collateral ligament runs from the lateral femoral condyle to the head of the fibula [1].
- The lateral collateral ligament is the main stabilizer against varus stress [1].
- The lateral collateral ligament is part of the posterolateral “complex” or “corner” of the knee that also resists external rotation [1].
- The popliteofibular ligament is present in 90% of knees and runs from the tendon of the popliteus muscle to the styloid on the posterior fibular head [1].
- The ACL is composed of 90% type I collagen and 10% type III collagen [4].
- The mean length of the ACL is 33 mm and the mean midsubstance width is 11 mm [4].
- The femoral attachment of the ACL is a semicircular area (20 mm long and 10 mm wide) on the posteromedial aspect of the lateral femoral condyle [4].
- The tibial attachment of the ACL is a broad, irregular, oval-shaped area (30 mm long and 10 mm wide) slightly medial and anterior to the midline and between the medial and lateral tibial spinous processes [4].
- The ACL is an intra-articular ligament but technically extrasynovial as it is surrounded by synovium [16].
- The ACL has a variable length of 22 to 41 mm and width of 7 to 12 mm, consistently narrowest in the midsubstance [16].
- The femoral origin of the ACL is on the posteromedial edge of the lateral femoral condyle, posterior to the lateral intercondylar ridge (Resident’s ridge) [16].
- The ACL attachment is usually oval in shape, with the anteromedial bundle arising from the superior and anterior aspects and the posterolateral bundle arising from the posterior and inferior aspects [16].
- The ACL bundles are often separated by the lateral bifurcate ridge, which runs from anterior to posterior on the femur [16].
- The bulk of the ACL anteromedial bundle is attached between 9.30 and 11.30 o'clock and the posterolateral bundle between 8.30 and 10 o'clock on a clock-face description based on the posterior outlet of the femoral intercondylar notch [16].
- The distance on the femur between the centers of the ACL bundles varies from 8 to 10 mm [16].
- The tibial footprint of the ACL is on the tibial plateau in the anterior intercondylar fossa, between the medial and lateral tibial spines [16].
- The tibial insertion of the ACL is 120% larger than the femoral insertion [16].
- The ACL anteromedial bundle is tight in knee flexion and the posterolateral bundle is tight in extension [4].
- The ACL anteromedial bundle is primarily an anterior restraint evaluated by Lachman and anterior drawer tests [5].
- The ACL posterolateral bundle is primarily a rotatory restraint evaluated by pivot shift test [5].
- The ACL is typically subjected to peak loads of 170 N during walking and up to 500 N with running [19].
- The ultimate strength of the ACL in young patients is about 1750 N [19].
- The ACL fails by serial tearing at 10% to 15% elongation [19].
- The PCL has a mean length of 38 mm and mean width of 13 mm [18].
- The PCL has a broad, crescent-shaped femoral attachment on the anterolateral medial femoral condyle with a mean length of 30 mm and mean width of 5 mm [18].
- The tibial insertion of the PCL onto the posterior central sulcus is 10 to 15 mm distal to the joint line of the knee [18].
- The PCL anterolateral bundle is stronger and stiffer than the posteromedial bundle and is tight in knee flexion [18].
- The PCL posteromedial bundle is tight in knee extension [18].
- Sectioning the PCL increases contact pressures in the medial compartment and the patellofemoral joint [19].
- The superficial medial collateral ligament (sMCL) proximal division resists valgus tibial translation and tibial external rotation [5].
- The sMCL distal division resists tibial external rotation in knee extension and tibial internal rotation [5].
- The deep MCL resists valgus translation and tibial internal and external rotation [5].
- The posterior oblique ligament resists tibial internal rotation, especially in knee extension, and tibial external rotation [5].
- The lateral collateral ligament resists varus tibial translation and tibial external rotation, especially at 30 degrees of knee flexion [5].
- The popliteus tendon resists tibial external rotation, especially in knee flexion, and varus tibial translation [5].
- The popliteofibular ligament resists tibial external rotation, especially in knee flexion, and posterior tibial displacement [5].
- The oblique popliteal ligament resists knee hyperextension and varus tibial translation [5].
- The joint capsule and the collateral ligaments are the principal extraarticular static stabilizing structures [7].
- The capsule is a sleeve of fibrous tissue extending from the patella and patellar tendon anteriorly to the medial, lateral, and posterior expanses of the joint [7].
- The medial capsule is more distinct and well defined than its lateral counterpart [7].
- The anteromedial and anterolateral portions of the capsule are relatively thin structures but are reinforced by the medial and lateral patellar retinacular expansions [7].
- The medial patellofemoral ligament runs from the patella near the junction of the middle and superior thirds to the medial femoral epicondyle [7].
- The posteromedial corner of the knee has five major components: the posterior oblique ligament, the semimembranosus tendon and its expansions, the oblique popliteal ligament, the posteromedial joint capsule, and the posterior horn of the medial meniscus [13].
- The posterior oblique ligament is attached proximally to the adductor tubercle of the femur and distally to the tibia and posterior aspect of the capsule [13].
- The distal attachment of the posterior oblique ligament is composed of three arms: the tibial arm, the capsular arm, and the distal arm [13].
- The central portion of the posterior oblique ligament is the thickest and probably the most important arm, originating in the region of the adductor tubercle [13].
- The semimembranosus tendon has five expansions: the direct arm, the anterior or deep arm, the arm to the posterior oblique ligament, the arm to the oblique popliteal ligament, and the expansion to the popliteus aponeurosis [13].
- The oblique popliteal ligament is a broad fascial band originating from the capsular arm of the posterior oblique ligament and the lateral expansion of the semimembranosus to cross the posterior aspect of the knee [13].
- The posteromedial capsule begins posterior to the superficial and deep MCL, with the deep MCL blending with and becoming inseparable from the central arm of the posterior oblique ligament [13].
- The posteromedial portion of the medial capsular ligamentous complex is especially important for valgus and rotational stability to the knee [13].
- The central arm of the posterior oblique ligament must be tightened in surgical repair or reconstruction, or passive stability cannot be attained regardless of any other surgical procedures [13].
Menisci¶
- The menisci are C-shaped fibrocartilaginous disks in the knee that provide shock absorption, allow for increased congruency between joint surfaces, enhance joint stability, and aid in distribution of synovial fluid [1].
- The medial and lateral menisci provide a concave surface with which the convex femoral condyles can articulate [1].
- Without menisci, the convex femoral condyles articulate with the relatively flat tibial plateaus, decreasing surface area of contact and increasing pressure on the articular cartilage [1].
- The medial meniscus is firmly attached to the joint capsule along its entire peripheral edge [1].
- The lateral meniscus is attached to the anterior and posterior capsule, but there is a region posterolaterally where it is not firmly attached [1].
- The medial meniscus has less mobility than the lateral meniscus and is more susceptible to tearing when trapped between the femoral condyle and tibial plateau [1].
- The lateral meniscus is larger than the medial meniscus and carries a greater share of the lateral compartment pressure than the medial meniscus carries for the medial compartment [1].
- The knee menisci are wedge-shaped fibrocartilaginous structures situated between the femoral condyles and tibial plateau [14].
- The medial meniscus has a semicircular shape, which covers approximately 50% to 60% of the medial tibial plateau in adulthood [14].
- The posterior horn of the medial meniscus averages 11 mm in the anterior-posterior dimension, whereas the anterior horn is narrower [14].
- The anterior horn of the medial meniscus attaches to the tibia anterior to the ACL near the intercondylar fossa [14].
- The transverse, or intermeniscal, ligament connects the anterior horns of the medial and lateral menisci [14].
- The posterior root attachment of the medial meniscus lies in the posterior intercondylar fossa between the lateral meniscus and PCL [14].
- The meniscotibial (coronary) ligament stabilizes the medial meniscus through its attachment from the inferior aspect of the posterior horn to the tibia [14].
- The medial meniscus is firmly attached to the deep medial collateral ligament and joint capsule, limiting its mobility [14].
- The lateral meniscus has a more circular C-shape with symmetric sizes of the anterior and posterior horns [14].
- The lateral meniscus anterior root attaches anterior to the intercondylar eminence and just lateral to the ACL insertion site on the tibia [14].
- The lateral meniscus posterior root attaches posterior to the lateral tibial spine just anterior to the medial meniscus posterior root [14].
- The popliteomeniscal fascicles extend from the lateral meniscus to the posterior capsule to create the popliteal hiatus [14].
- The meniscofemoral ligaments are variably present structures which connect the posterior horn of the lateral meniscus to the medial femoral condyle [14].
- The ligament of Humphrey crosses anterior to the PCL and the ligament of Wrisberg crosses posteriorly [14].
- The less continuous attachment of the lateral meniscus to the capsule allows for
Investigations¶
Plain Radiography¶
- Plain radiographs are appropriate initial imaging studies for most knee conditions because they allow the assessment of traumatic injury, arthritis, patellofemoral alignment, osteochondral injury, bone neoplasm, and surgical implants [22].
- Imaging studies should include at least two perpendicular views: AP and lateral [22].
- Weight-bearing AP (extension) views are used to assess cartilage loss from the distal femur and tibial plateau [22].
- Weight-bearing PA (Rosenberg; flexion) views are used to assess cartilage loss from the posterior femur and tibial plateau [22].
- Patellofemoral views are used to assess patellofemoral alignment (tilt/subluxation), patellar and trochlear morphology, osteochondral injury, and patellofemoral arthritis [22].
- Notch views are used to assess posterior femoral cartilage, notch width, and osteophytes [22].
- Non–weight-bearing radiographs may identify acute injury without the risk of fracture displacement in trauma cases [22].
- Radiographs should be inspected for acute fracture, lateral capsular avulsion (Segond fracture), loose bodies, Pellegrini-Stieda lesion (MCL calcification), and evidence of patellar dislocation [10].
- Stress radiographs should be obtained in patients prior to skeletal maturity to rule out an epiphyseal fracture [10].
- Radiographs can underestimate isolated chondral lesions but may demonstrate joint space narrowing, osteophytes, sclerosis, and cysts [26].
- Weight-bearing AP and lateral views and an axial view of the patellofemoral joint should be reviewed for articular cartilage evaluation [26].
- The ability to detect subtle narrowing or an isolated chondral defect on the flexion surface may be improved with a semiflexed PA view [26].
- Long leg alignment views are used to determine the mechanical axis [26].
- If the mechanical axis traverses the involved compartment (varus knees with medial compartment lesions or valgus knees with lateral compartment lesions), realignment may need to be considered as an initial procedure or as an adjunct to a cartilage restorative procedure [26].
- Radiographs are still the standard for initial evaluation of knee arthritis [30].
- Images for knee arthritis evaluation should include weight-bearing AP and lateral views, a view of the weight-bearing knee flexed at 45-degree angle imaged posterior to anterior, a sunrise view (Merchant view), extension and flexion lateral views, and a standing full-length AP radiograph [30].
- A standing full-length AP radiograph from hip joint to ankle joint is used to evaluate limb alignment and knee deformity and to identify femoral and/or tibial bone deformity [30].
- Radiographs should be inspected for acute fractures, lateral capsular avulsion (Segond fracture), loose bodies, fibular head avulsions, and evidence of patellar dislocation in suspected LCL injuries [31].
- With chronic posterolateral instability, degenerative changes of the lateral compartment are often noted on radiographs, including lateral joint space narrowing with osteophytes and subchondral sclerosis [31].
- Stress radiographs can help to better quantify the amount of varus angulation present in LCL injuries [31].
Computed Tomography¶
- Computed tomography provides a three-dimensional study with ionizing radiation that provides enhanced bone detail [22].
- Imaging in the axial, sagittal, and coronal planes may help visualize fracture lines and displacement, osteolytic lesions around joint arthroplasty, and cortical disruption in cases of infection or neoplasia [22].
- Three-dimensional reconstructions may help with preoperative planning for complex intra-articular fractures, multiplanar osteotomy for limb malalignment, and reconstitution of bone loss in joint arthroplasty [22].
- Axial plane imaging of the hip and knee can help assess the rotational alignment of components of a total knee arthroplasty in cases of patellar maltracking [22].
- Three-dimensional CT with remodeling is used for preoperative planning for reconstruction associated with dysplasia, post-trauma planning, and complex total knee arthroplasty (TKA) planning [30].
Magnetic Resonance Imaging¶
- Increasing strength of the magnetic field (measured in Tesla units) increases the resolution of images [22].
- An injected contrast agent (intravenous or intra-articular) may help delineate specific tissues of interest in MRI [22].
- MRI may identify the presence of edema, intra-articular fluid, disruption of ligament fibers, and an atypical ligament contour to suggest cruciate ligament injury [22].
- MRI can identify patterns of meniscal injury by location (anterior, midbody, posterior, peripheral, articular), pattern (horizontal, longitudinal, radial, complex), and displacement [22].
- MRI may identify the degree of articular cartilage injury (chondrosis, full-thickness cartilage loss), the presence of associated bone marrow edema, and the location (medial condyle, lateral condyle, trochlea, patella; anterior, posterior) [22].
- MRI may identify edema, avulsion, or discontinuity for the MCL/lateral collateral ligament (LCL) or associated posteromedial and posterolateral ligamentous complexes [22].
- MRI may be used to assess the continuity of the quadriceps or patellar tendon [22].
- MRI may be used to assess the margin of resection for a neoplasm, identify vascular malformation, or define the location of nerves or vessels relative to popliteal cysts [22].
- MRI is useful for confirming MCL injury and identifying the site of injury [10].
- MRI is useful to detect the presence of meniscal and other injuries to the knee in MCL injuries [10].
- Relative indications for an MRI in MCL injuries include an uncertain ACL status despite multiple examinations, evaluation of a suspected meniscal tear, or preoperative evaluation for a planned MCL reconstruction or repair [10].
- MRI is often a useful adjunct for diagnosing posterolateral corner and LCL injuries in the severely injured knee [31].
- MRI findings can refocus the examination to the posterolateral structures when posterolateral injury can often go unnoticed during an initial evaluation [31].
- MRI is not indicated if the joint space is significantly narrowed on radiograph in the arthritic patient population [30].
- MRI is used when osteonecrosis is suspected in the arthritic patient population [30].
- MRI can be used to evaluate articular cartilage morphology [26].
Nuclear Medicine¶
- Nuclear medicine involves labeled radionuclide injection followed by delayed imaging of gamma radiation, where areas of increased radionuclide concentration appear bright or “hot” [22].
- Nuclear medicine provides a nonspecific study that does not define the etiology of an abnormality but rather the presence of an abnormality that may correlate with a clinical concern [22].
- Increased radionuclide activity in bone may be a normal postoperative finding for up to 6 to 12 months after a fracture repair or arthroplasty [22].
- Technetium-99 (Tc-99) is a radionuclide that may help identify infection, neoplasia, occult fracture, bone healing, active phases of heterotopic ossification, implant loosening, or failure of osseointegration [22].
- Gallium-67 (Ga-67) is a radionuclide that may help differentiate between aseptic and septic prosthetic loosening; 24 to 72 hours are needed for a complete study [22].
Physical Examination¶
- The physical examination begins with observation of the patient’s gait, followed by examination of the uninjured knee as a basis of comparison with the injured knee [1].
- Any swelling or effusion should be noted during physical examination [1].
- A small effusion will cause obliteration of the recesses on the medial and lateral aspects of the patellar tendon; with a larger effusion, diffuse swelling is present in the region of the suprapatellar pouch [1].
- A fluid wave can be palpated on the sides of the patella [1].
- Active and then passive range of motion is tested carefully during physical examination [1].
- The knee is palpated to define areas of localized tenderness [1].
- The joint lines are located at the level of the inferior pole of the patella when the knee is flexed to 90 degrees [1].
- Laxity to valgus stresses is assessed by the amount of medial joint space opening that occurs at 30 degrees of flexion for MCL injuries [10].
- Zero opening is considered normal, with 1-4 mm indicating a grade I injury, 5–9 mm indicating a grade II injury, and 10–15 mm indicating a complete or grade III injury for MCL injuries [10].
- Grade I and II MCL injuries typically have a firm end point, whereas a grade III injury tends to have a soft end point to valgus stress [10].
- The integrity of the LCL is assessed by placing a varus stress, with the knee in full extension and 30 degrees of flexion [31].
- The average baseline for varus opening is 7 degrees [31].
- Exam findings with an isolated LCL injury should include varus laxity at 30 degrees of flexion and no instability in full extension [31].
- The dial test is performed by externally rotating each tibia and noting the angle subtended between the thigh and the foot at 30 and 90 degrees of flexion [31].
- A significant difference in the dial test is an angle 5 degrees or greater than the contralateral leg [31].
- Injury to the posterolateral capsule alone is confirmed with greater external rotation at 30 degrees, an isolated PCL at 90 degrees, and to both structures when there is greater rotation at 30 and 90 degrees compared to the uninjured leg [31].
- A careful neurovascular examination should be performed as the incidence of neurovascular injury, particularly peroneal nerve injury, has been reported in 12–29% of posterolateral knee injuries [31].
- An examination under anesthesia can be valuable when physical examination is unreliable because of the patient guarding the knee [10].
- Diagnostic arthroscopy can be used to evaluate for coexisting pathology, though both examination under anesthesia and diagnostic arthroscopy have largely been replaced by MRI [10].
- An examination while the patient is relaxed under general anesthetic is extremely useful, particularly in the acute setting for multiligamentous knee injuries [31].
Treatment¶
- Substantial improvements in implant design and understanding the determinants of achieving a good clinical outcome have been achieved in the management of distal femur fractures [3].
- The evaluation and management of distal femur fractures require an understanding of the injury mechanism, potential associated injuries, and radiographic and clinical goals [3].
- Surgical management of distal femur fractures requires a clear understanding of the unique anatomy of the distal femur [3].
- Surgical management of distal femur fractures requires comprehensive knowledge of the implant and how it can be used in a biologic-preserving manner to achieve an anatomic reduction and enable fracture healing [3].
- Understanding the unique anatomy of the distal femur is necessary to achieve an anatomic reduction [3].
- Understanding the unique anatomy of the distal femur is necessary for successful maintenance of reduction using modern implants [3].
- Clinical and radiographic assessment of both soft-tissue and osseous injury to the distal femur helps define surgical treatment options [3].
- An understanding of expected outcomes and potential postoperative complications related to the surgical management of distal femur fractures is important for optimal results [3].
References¶
[1] A Lange Medical Book Current Diagnosis Treatment In Orthopedics Fifth Edition. 3Sports Medicine > Image KNEE INJURIES.
[3] Orthopaedic Knowledge Update Trauma. Fractures of the Distal Femur > Summary.
[4] Aaos Comprehensive Orthopaedic Review 3. Anatomy and Biomechanics of the Knee > I. Anatomy.
[5] Miller S Review Of Orthopaedics. SECTION 1 KNEE > ANATOMY (FIG. 4.1).
[7] Campbell S Operative Orthopaedics 4 Volume Set. EXTRAARTICULAR LIGAMENTOUS STRUCTURES.
[10] A Lange Medical Book Current Diagnosis Treatment In Orthopedics Fifth Edition. 3Sports Medicine > 1. Medial Collateral Ligament Injuries.
[13] Campbell S Operative Orthopaedics 4 Volume Set. POSTEROMEDIAL CORNER.
[14] Orthopaedic Basic Science Fifth Edition Print Ebook. Biology and Mechanics of the Skeletal Extracellular Matrix > Gross Anatomy.
[16] Rockwood And Green S Fractures In Adults. 59: Patellar Fractures and Dislocations and Extensor Mechanism Injuries > Anterior Cruciate Ligament Anatomy.
[18] Aaos Comprehensive Orthopaedic Review 3. Radiographic Evaluation and Surgical Anatomy of the Knee > II. Surgical Anatomy of the Knee.
[19] Miller S Review Of Orthopaedics. ARTHRODESIS PERSON > Kinetics.
[22] Aaos Comprehensive Orthopaedic Review 3. Radiographic Evaluation and Surgical Anatomy of the Knee > I. Radiographic Evaluation.
[24] Aaos Comprehensive Orthopaedic Review 3. Knee Dislocations and Patellar Fractures* > I. Knee Dislocations.
[26] Aaos Comprehensive Orthopaedic Review 3. Articular Cartilage Injury and Treatment > IV. Full-Thickness Outerbridge Grade IV Defects.
[30] Miller S Review Of Orthopaedics. SECTION 16 PATELLAR TRACKING IN TOTAL KNEE ARTHROPLASTY > SECTION 11 KNEE ARTHRITIS ASSESSMENT.
[31] A Lange Medical Book Current Diagnosis Treatment In Orthopedics Fifth Edition. 3Sports Medicine > 2. Lateral Collateral Ligament Injuries.
