-i-
`
`Smith & Nephew Ex. 1042
`IPR Petition - USP 7,534,263
`
`

`
`DROR PALEY
`
`PRINCIPLES OF DE F 0 RM I TY
`CORRECTION
`
`With Editorial Assistance from J.E. Herzenberg
`
`With More Than 1,800 Separate Illustrations,
`Clinical Photographs, and Radiographs
`
`i Springer
`
`-ii-
`
`

`
`DROR PALEY,MD,FRCSC
`
`Director, Rubin Institute for Advanced Orthopedics
`Sinai Hospital
`Co-Director, The International Center
`for Limb Lengthening, Sinai Hospital
`Baltimore, MD
`
`Present address:
`
`Rubin Institute for Advanced Orthopedics
`Sinai Hospital
`2401 West Belvedere Avenue
`Baltimore, Maryland 21215-5271, USA
`
`E-mail: dpaley@lifebridgehealth.org
`
`www.limblengthening.org
`
`www.deformitycourse.com
`
`ISBN 978-3-642-59373-4 (eBook)
`ISBN 978-3-642-63953-1
`DOI 10. l 007/978-3-642-59373-4
`
`1st ed. 2002. Corr. 3rd printing 2005
`
`CfP-data applied for
`
`Die Deutsche Bibliothek - CIP-Einheitsaufnahme
`Paley, Dror: Principles of deformity correction I Dror Paley. -
`Berlin ; Heidelberg ; New York ; Barcelona ; Hongkong ;
`London; Mailand ; Paris ; Singapur ; Tokio : Springer, 2002
`
`This work is subject to copyright. All rights are reserved,
`whether the whole or part of the material is concerned, specif(cid:173)
`ically the rights of translation, reprinting, reuse of illustrations,
`recitation, broadcasting, reproduction on microfilm or in any
`other way, and storage in data banks. Duplication of this pub(cid:173)
`lication or parts thereof is permitted only under the provisions
`of the German Copyright Law of September 9, 1965, in its cur(cid:173)
`rent version, and permission for use must always be obtained
`from Springer-Verlag. Violations are liable for prosecution
`under the German Copyright Law.
`
`http://www.springer.de
`
`©Springer-Verlag Berlin Heidelberg 2002
`Originally published by Springer-Verlag Berlin Heidelberg
`New York in 2002
`Softcover reprint of the hardcover 1st edition 2002
`
`The use of general descriptive names, registered names, trade(cid:173)
`marks, etc. in this publication does not imply, even in the
`absence of a specific statement, that such names are exempt
`from the relevant protective laws and regulations and therefore
`free for general use.
`
`Product liability: The publishers cannot guarantee the accu(cid:173)
`racy of any information about dosage and application con(cid:173)
`tained in this book. ln every individual case the user must
`check such information by consulting the relevant literature.
`
`Cover design: E. Kirchner, Heidelberg
`Product management and layout: B. Wieland, Heidelberg
`Typesetting and production: AM-production, Wiesloch
`
`24/3150 - 5 4 3 2 l 0
`Printed on add-free paper
`
`-iii-
`
`

`
`CHAPTER 1
`
`Normal Lower Limb Alignment and Joint Orientation
`
`_____ ..
`
`To understand deformities of the lower extremity, it is
`important to first understand and establish the parame(cid:173)
`ters and limits of normal alignment. The exact anatomy
`of the femur, tibia, hip, knee, and ankle is of great impor(cid:173)
`tance to the clinician when examining the lower limb
`and to the surgeon when operating on the bones and
`joints. To better understand alignment and joint orien(cid:173)
`tation, the complex three-dimensional shapes of bones
`and joints can be simplified to basic line drawings, sim(cid:173)
`ilar to the stick figures a child uses to represent a person
`( ... Fig. 1-1).
`
`Furthermore, for purposes of reference, these line
`drawings should refer to either the frontal, sagittal, or
`transverse anatomic planes. The two ways to generate a
`line in space are to connect two points and to draw a line
`through one point at a specific angle to another line. All
`the lines that we use for planning and for drawing sche(cid:173)
`matics of the bones and joints are generated using one
`of these two methods (""Fig. 1-2).
`
`a. •- -·- -·-------- ···--·--·--- ·- . ··--·•
`
`b.
`
`Fig. Ha,b
`Two methods of drawing a line in space.
`a Connect two points.
`b Draw a line through one point at a specific angle to another
`line.
`
`Mechanical and Anatomic Bone Axes
`
`Each long bone has a mechanical and an anatomic axis
`(""Fig. 1-3). The mechanical axis of a bone is defined as
`the straight line connecting the joint center points of the
`proximal and distal joints. The anatomic axis of a bone
`is the mid-diaphyseal line. The mechanical axis is always
`a straight line connecting two joint center points, wheth(cid:173)
`er in the frontal or sagittal plane. The anatomic axis line
`may be straight in the frontal plane but curved in the
`sagittal plane, as in the femur. Intramedullary nails
`(IMN) designed for the femur have a sagittal plane arc
`to reflect this. In the tibia, the anatomic axis is straight in
`
`Fig.1-1
`Axis lines. A stick figure can be used as a schematic of a com(cid:173)
`plex three-dimensional image of a person. In the same fashion,
`axis and joint lines can be used to describe alignment and joint
`orientation of the bones and joints of the lower limb.
`
`anton.kurtz@gmail.com
`
`-1-
`
`

`
`B
`
`CHAPTER 1 • Normal Lower Limb Alignment and Joint Orientation
`
`a.
`
`I
`
`b.
`
`Mechanical axis
`
`Anatomic axis
`
`Mechanical axis
`
`Anatomic axis
`
`c.
`
`d.
`
`Mechanical axis
`
`Anatomic axis
`
`Mechanical axis
`
`Anatomic axis
`
`Fig. Ha-d
`Mechanical and anatomic axes of bones. The mechanical axis
`is the line from the center of the proximal joint to the center of
`the distal joint. The mechanical axis is always a straight line
`because it is always defined from joint center to joint center.
`Therefore, the mechanical axis line is straight in both the fron(cid:173)
`tal and sagittal planes of the femur and tibia. The anatomic
`axis of a long bone is the mid-diaphyseal line of that bone. In
`straight bones (a, c), the anatomic axis follows the straight mid(cid:173)
`diaphyseal path. In curved bones (b, d), it follows a curved mid(cid:173)
`diaphyseal path. The anatomic axis can be extended into the
`metaphyseal and juxta-articular portions of a bone by extend(cid:173)
`ing its mid-diaphyseal line in either direction.
`
`Fig. 1·4 a, b ,...
`
`a The tibial mechanical and anatomic axes are parallel but not
`the same. The anatomic axis is slightly medial to the me(cid:173)
`chanical axis. Therefore, the mechanical axis of the tibia is
`actually slightly lateral to the midline of the tibial shaft. Con(cid:173)
`versely, the anatomic axis does not pass through the center
`of the knee joint. It intersects the knee joint line at the medi(cid:173)
`al tibial spine.
`b The femoral mechanical and anatomic axes are not parallel.
`The femoral anatomic axis intersects the knee joint line gen(cid:173)
`erally l cm medial to the knee joint center, in the vicinity of
`the medial tibial spine. When extended proximally, it usual(cid:173)
`ly passes through the piriformis fossa just medial to the
`greater trochanter medial cortex. The angle between the
`femoral mechanical and anatomic axes (AMA) is 7±2°.
`
`both frontal and sagittal planes ("'Fig. 1-3). Axis lines
`are applicable to any longitudinal projection of a bone.
`For practical purposes, we refer only to the two anatom(cid:173)
`ic planes, frontal and sagittal. The corresponding radio(cid:173)
`graphic projections are the anteroposterior (AP) and
`lateral (LAT) views, respectively.
`
`In the tibia, the frontal plane mechanical and ana(cid:173)
`tomic axes are parallel and only a few millimeters apart.
`Therefore, the tibial anatomic-mechanical angle (AMA)
`is 0° ("' Fig. l-4a). In the femur, the mechanical and an(cid:173)
`atomic axes are different and converge distally ("' Fig.
`l -4b). The normal femoral AMA is 7±2°.
`
`anton.kurtz@gmail.com
`
`-2-
`
`

`
`CHAPTER 1 · NormallowerlimbAlignmentandJointOrientation . .
`
`a.
`
`b.
`
`Mechanical axis
`
`Anatomic axis
`
`P~tomic
`
`axis
`
`Mechanical
`axis
`
`Mechanical axis
`
`Anatomic axis
`
`Mechanical Anatomic
`axis
`axis
`
`anton.kurtz@gma1l.com
`
`-3-
`
`

`
`B
`
`CHAPTER 1 · Normal Lower Limb Alignment and Joint Orientation
`
`a.
`
`b.
`
`c.
`
`iii
`
`ii
`
`... ·····+·· Ap0< 01 tomo1'1 "'~"
`
`.... ······· ..... ~ ......... ....... Midpoint of femoral condyles
`\
`.. ··::::'........... )
`1
`4
`.. ···~
`/ l .. -....;: ............................... Center of tibial spines
`'( \
`~· ·..
`
`·· .... :::::.'.'.'.'.'.'.'.'.'.) ""· ........... Midpoint of soft tissue outline
`
`(
`
`.......... ) .... Mldpolof ol 'bl•I plot" "'
`
`I
`
`\ .!..\ .............. Ceoto1 ol wft ' ""'
`)
`............... center bones
`,..-::~:::::::r::::.\ ... )
`
`~l Y · ...... )\.'\:) .................. Center of talus
`1
`I
`
`anton.kurtz@gmail.com
`
`-4-
`
`

`
`Joint Center Points
`
`Joint Orientation Lines
`
`CHAPTER 1 • Normal Lower LimbAlignmentandJointOrientation H
`
`As noted above, the mechanical axis passes through the
`joint center points. Because the mechanical axis is con(cid:173)
`sidered mostly in the frontal plane, we need to define
`only the frontal plane joint center points of the hip, knee,
`and ankle(..,... Fig.1-5). Moreland et al. (1987) studied the
`joint center points of the hip, knee, and ankle.
`For the hip, the joint center point is the center of the
`circular femoral head. The center of the femoral head
`can best be identified using Mose circles. Practically, we
`can use the circular part of a goniometer to define this
`point(..,... Fig. 1-5 a).
`Moreland et al. (1987) evaluated different geometric
`methods to define the center of the knee joint. They
`demonstrated that the center of the knee joint is approx(cid:173)
`imately the same using a point at the top of the femoral
`notch, the midpoint of the femoral condyles, the center
`of the tibial spines, the midpoint of the soft tissue
`around the knee, or the midpoint of the tibial plateaus
`(..,... Fig. 1-5 b). Using the top of the femoral notch or tibi(cid:173)
`al spines is the quickest way to mark the knee joint cen(cid:173)
`ter point without measuring the width of the bones or
`soft tissues.
`Similarly, the ankle joint center point is the same
`whether measured at the mid-width of the talus, the
`mid-width of the tibia and fibula at the level of the pla(cid:173)
`fond, or the mid-width of the soft tissue outline (..,... Fig.
`l-5c). The mid-width of the talus or the plafond is the
`easiest to use.
`
`A line can also represent the orientation of a joint in a
`particular plane or projection. This is called the joint ori(cid:173)
`entation line(..,... Fig. 1-6).
`
`Ankle
`
`At the ankle, the joint orientation line in the frontal
`plane is drawn across the fiat subchondral line of the tib(cid:173)
`ial plafond in either the distal tibial subchondral line or
`for the subchondral line of the dome of the talus (..,...Fig.
`l-6a). In the sagittal plane, the ankle joint orientation
`line is drawn from the distal tip of the posterior lip to the
`distal tip of the anterior lip of the tibia(..,... Fig. l-6b).
`
`Knee
`
`The frontal plane knee joint line of the proximal tibia is
`drawn across the flat or concave aspect of the subchon(cid:173)
`dral line of the two tibial plateaus (..,... Fig. l -6c). The
`frontal plane knee joint orientation line of the distal
`femur is drawn as a line tangential to the most distal
`points on the convexity of the two femoral condyles
`(..,... Fig. l-6 d). In the sagittal plane, the proximal joint
`line of the tibia is drawn along the flat subchondral line
`of the plateaus(..,... Fig. l-6e). In the sagittal plane, the dis(cid:173)
`tal femoral articular shape is circular. The distal femoral
`
`~ Fig. Ha-c
`a The midpoint of the femoral head is best identified using
`Mose circles (i). If these are unavailable, measure the longi(cid:173)
`tudinal diameter of the femoral head and divide it in two.
`Use this distance to measure from the medial edge of the
`femoral head. The center of the femoral head is located
`where the distance to the medial border of the femoral head
`is the same as half of the longitudinal diameter (ii). Practi(cid:173)
`cally, we can use the circular part of a goniometer to define
`this point (ill). r, radius.
`b The midpoint of the knee joint line corresponds to the mid(cid:173)
`point between the tibial spines on the tibial plateau line and
`the apex of the intercondylar notch on the femoral articular
`surface. These points are not significantly different from the
`mid condylar point of the distal femur and the mid plateau
`point of the proximal tibia (modified from Moreland et al.
`1987).
`c The midpoint of the ankle joint line corresponds to the mid(cid:173)
`point of the tibial plafond measured between the medial ar(cid:173)
`ticular aspect of the lateral malleolus and the lateral articu(cid:173)
`lar aspect of the medial malleolus. The mid-width of the
`talus and the mid-width of the ankle measured clinically
`yield the same point (modified from Moreland et al. 1987).
`
`Fig. 1-6 a-h ....
`
`a Ankle joint orientation line, frontal plane. Connect two
`points at either end of the ankle plafond line.
`b Ankle joint orientation line, sagittal plane. Connect two
`points from anterior to posterior lip of joint.
`c Proximal tibial knee joint orientation line, frontal plane.
`Connect two points on the concave aspect of the tibial pla(cid:173)
`teau subchondral line.
`d Distal femoral knee joint orientation line, frontal plane.
`Draw a line tangent to the two most convex points on the
`femoral condyles.
`e Proximal tibial knee joint orientation line, sagittal plane.
`Draw a line along the flat portion of the subchondral bone.
`Distal femoral joint orientation line, sagittal plane. Connect
`the two anterior and posterior points where the condyle
`meets the metaphysis. For children, this is drawn where the
`growth plate exits anteriorly and posteriorly.
`g Neck of femur line, frontal plane. Draw a line from the cen(cid:173)
`ter of the femoral head through the mid-diaphyseal point of
`the narrowest part of the femoral neck.
`h Hip joint orientation line, frontal plane. Draw a line from the
`proximal tip of the greater trochanter to the center of the
`femoral head.
`
`anton.kurtz@gmail.com
`
`-5-
`
`

`
`B
`
`CHAPTER 1 • Normal Lower Limb Alignment and Joint Orientation
`
`a.
`
`c.
`
`b.
`
`d.
`
`anton.kurtz@gmail.com
`
`-6-
`
`

`
`e.
`
`f.
`
`CHAPTER 1 • Normal Lower Limb Alignment and Joint Orientation . .
`
`Growth plate
`open
`
`Growth plate
`closed
`
`g.
`
`h.
`
`Fig.1-6 a-h
`
`anton.kurtz@gmail.com
`
`-7-
`
`

`
`B
`
`CHAPTER 1 • Normal Lower Limb Alignment and Joint Orientation
`
`joint orientation can be drawn as a straight line connect(cid:173)
`ing the two points where the femoral condyles meet the
`metaphysis of the femur. For children, this can be drawn
`where the growth plate exits anteriorly and posteriorly
`( ~ Fig. 1-6 f). Alternatively, Blumensaat's line, which can
`be seen as a flat line representing the intercondylar
`notch, can be used as the joint orientation line of the dis(cid:173)
`tal femur in the sagittal plane. This is particularly useful
`for evaluating sagittal plane deformities secondary to
`growth arrest problems.
`
`Hip
`
`Because the femoral head is round, it is necessary to use
`the femoral neck or the greater trochanter to draw a
`joint line for hip orientation in the frontal plane (~ Fig.
`1-6 g). The level of the tip of the greater trochanter has a
`functional and developmental relationship to the center
`of the femoral head. Similarly, the femoral neck main(cid:173)
`tains a developmental relationship to the femoral dia(cid:173)
`physis and femoral head.A line from the proximal tip of
`the greater trochanter to the center of the femoral head
`represents the hip joint orientation line of the hip joint
`in the frontal plane. Alternatively, the mid-diaphyseal
`line of the femoral neck can represent the orientation of
`the hip joint(~ Fig. l-6h). This is drawn using the cen(cid:173)
`ter of the femoral head as one point and the mid-diaphy(cid:173)
`seal width of the neck as the second point.
`
`Joint Orientation Angles and Nomenclature
`
`The joint lines in the frontal and sagittal planes have a
`characteristic orientation to the mechanical and ana(cid:173)
`tomic axes. For purposes of communication, it is impor(cid:173)
`tant to name these angles. These joint orientation angles
`have been given various names by different authors in
`different publications (Chao et al. 1994; Cooke et al.
`1987, 1994; Krackow 1983; Moreland et al. 1987). There is
`no standardization of the nomenclature used in the lit(cid:173)
`erature. This makes communication and comparison
`difficult. We think that the names used by different au(cid:173)
`thors are confusing, difficult to remember, and not user
`friendly. The nomenclature used in this text was devel(cid:173)
`oped so that the names could be easily remembered or
`even derived without memorization (Paley et al. 1994).
`In the frontal and sagittal planes, a joint line can be
`drawn for the hip, knee, and ankle. The angle formed be(cid:173)
`tween the joint line and either the mechanical or ana(cid:173)
`tomic axis is called the joint orientation angle. The name
`of each angle specifies whether it is measured relative to
`a mechanical (m) or an anatomic (a) axis. The angle may
`be measured medial (M),lateral (L),anterior (A),or pos(cid:173)
`terior (P) to the axis line. The angle may refer to the
`proximal (P) or distal (D) joint orientation angle of a
`
`a.
`
`Mechanical
`
`LPFA : 90°
`(85-95°)
`
`JLCA
`(0-2')
`
`Y.PTA=87'
`(85-90°)
`
`LOTA =89°
`(86-92/tf
`
`Fig. 1-7 a-e
`a Frontal plane joint orientation angle nomenclature and nor(cid:173)
`mal values relative to the mechanical axis.
`b Frontal plane joint orientation angle nomenclature and nor(cid:173)
`mal values relative to the anatomic axis. MNSA, medial NSA.
`c Sagittal plane joint orientation angle nomenclature and nor(cid:173)
`mal values relative to the anatomic axis. aPPFA, anatomic
`posterior proximal femoral angle; aADTA, anatomic anteri(cid:173)
`or distal tibial angle.
`d Anatomic axis-joint line intersection points. JCDs for the
`frontal plane.
`e Anatomic axis-joint line intersection points. JERs for the
`sagittal plane.
`
`bone (femur [F) or tibia [T)). Therefore, the mechanical
`lateral distal femoral angle (mLDFA) is the lateral angle
`formed between the mechanical axis line of the femur
`and the knee joint line of the femur in the frontal plane.
`Similarly, the anatomic LDFA (aLDFA) is the lateral
`angle formed between the anatomic axis of the femur
`and the knee joint line of the femur in the frontal plane.
`Sagittal plane angles can just as easily be named. For
`example, the anatomic posterior proximal tibial angle
`(aPPTA) is the posterior angle between the anatomic
`axis of the tibia and the joint line of the tibia in the sag(cid:173)
`ittal plane.
`Schematic drawings of the nomenclature of the me(cid:173)
`chanical and anatomic frontal(~ Fig. l -7a and b) and
`
`anton.kurtz@gmail.com
`
`-8-
`
`

`
`b.
`
`Anatomic
`
`CHAPTER 1 · Normal Lower Limb Alignment and Joint Orientation B
`c.
`
`Sagittal
`
`PPFA =90°
`
`ANSA = 170°
`(165-175. )
`
`PDFA= 83°
`(79-87°)
`
`PPTA = 81 '
`(77-84°)
`
`LDTA =89.
`(86-92°.Yff
`
`ADTA = 80'
`(78- 82°)
`
`d.
`
`e.
`
`aJCD = piriformis Iossa
`
`1
`a·JER = /3
`
`aJCO = medial tibial spine
`10± 5 mm
`
`1
`a-JER= / 5
`
`1
`a-JER = /2
`
`aJCD = 4 ± 4mm
`
`anton.kurtz@gmail.com
`
`-9-
`
`

`
`m CHAPTER 1 • Normal Lower Limb Alignment and Joint Orientation
`
`sagittal (.,.Fig. l-7c) plane joint orientation angles are
`shown. Each axis line and joint orientation line intersec(cid:173)
`tion forms two angles. Either angle could be named with
`this nomenclature. For example, the mechanical medial
`distal femoral angle (mMDFA) and the mLDFA are com(cid:173)
`plementary to each other (they add up to 180°). Al(cid:173)
`though either angle could be used to name the joint ori(cid:173)
`entation angle of the knee to the mechanical axis of the
`femur, the mLDFA is the one used in this text (.,. Fig.
`l-7a). The angles chosen in this text are those that are
`normally less than 90° (normal value of the mLDFA = 87°
`and normal value of the mMDFA=93°). If the normal
`joint orientation was 90°, such as for the mechanical lat(cid:173)
`eral proximal femoral angle (mLPFA) and mechanical
`medial proximal femoral angle (mMPFA), the lateral an(cid:173)
`gle was chosen as the standard angle in this text. When
`it is obvious that the joint orientation angle refers to the
`mechanical or anatomic axis, the m or a prefix can be
`omitted. For example, sagittal plane orientation angles
`usually refer to the anatomic axis because mechanical
`axis lines are rarely used in the sagittal plane. The prefix
`m or a is omitted because anatomic axis is implied. Be(cid:173)
`cause the mechanical and anatomic axes of the tibia are
`parallel, the medial proximal tibial angle (MPTA) and
`lateral distal tibial angle (LOTA) have the same value
`whether they refer to the mechanical or anatomic axis. It
`therefore does not matter whether the prefix m or a is
`used. Finally, because LPFA is used by convention to de(cid:173)
`scribe joint orientation of the hip relative to the mechan(cid:173)
`ical axis and MPFA is used relative to the anatomic axis,
`the m and a prefixes can be omitted. Therefore, the only
`time the m or a prefix must be used is with reference to
`the LDFA. The mLDFA and the aLDFA are both normal(cid:173)
`ly less than 90° and are different from each other. There(cid:173)
`fore, the prefix should always be used to define which
`LDFA is being referenced.
`The angle formed between joint orientation lines on
`opposite sides of the same joint is called the joint line
`convergence angle (JLCA) (.,.Fig. l-7a and b). In the
`knee and ankle joints, these lines are normally parallel.
`Two mid-diaphyseal points define anatomic axis
`lines. The intersection of the anatomic axis with the joint
`line is fairly constant and is important in understanding
`normal alignment and in planning for deformity correc(cid:173)
`tion. The distance from the intersection point of ana(cid:173)
`tomic axis lines with the joint line can be described rel(cid:173)
`ative to the center of the joint line or to one of its edges.
`In the frontal plane, the distance on the joint line be(cid:173)
`tween the intersection with the anatomic axis line and
`the joint center point is called the anatomic axis to joint
`center distance (aJCD) (.,.Fig. l-7d). In the sagittal
`plane, the distance between the point of intersection of
`the anatomic axis line with the joint line and the anteri(cid:173)
`or edge of the joint is called the anatomic axis to joint
`edge distance (aJED). The anatomic axis:joint edge ratio
`(aJER) is the ratio between the aJED and the total width
`
`a.
`
`Shave et al., unpublished results 4.1 ± 4 mm
`Paley et al., 1994
`9.7 ± 6.8 mm
`
`of the joint. Similarly, the anatomic axis: joint center
`ratio (aJCR) is the ratio of the aJCD and the total width
`of the joint. The normal values and range are illustrated
`(.,.Fig. l-7e).
`
`Mechanical Axis and Mechanical Axis Deviation
`(MAD)
`
`The normal relationship of the joints of the lower ex(cid:173)
`tremity has been the focus of several recent studies
`(Chao et al. 1994; Cooke et al. 1987, 1994; Hsu et al. 1990;
`Moreland et al. 1987; Paley et al. 1994). There are two
`considerations when evaluating the frontal plane of the
`lower extremity: joint alignment and joint orientation
`(Paley and Tetsworth 1992; Paley et al. 1990). Alignment
`refers to the collinearity of the hip, knee, and ankle
`(.,.Fig. l-8a). Orientation refers to the position of each
`articular surface relative to the axes of the individual
`limb segments (tibia and femur) (.,. Fig. l -8b). Align(cid:173)
`ment and orientation are best judged using long stand-
`
`anton.kurtz@gmail.com
`
`-10-
`
`

`
`b.
`
`CHAPTER 1 · Normal Lower Limb Alignment and Joint Orientation Ill
`c.
`
`Mechanical
`tibiofemoral
`angle
`
`y;.,PTA
`
`d.
`
`Anatomic
`1.r- tibiofernoral
`If,
`angle
`
`Shave et al., unpublished results
`Chao et al., 1994
`Cook et al., 1994
`Hsu et al., 1990
`Moreland et al., 1987
`
`1.3 :I: 1.3·
`1.2 :I: 2.2·
`1 :1: 2.a ·
`1.2 :I: 2.2·
`1.3:1: 2·
`
`Fig. 1·8a-d
`a MAD is the perpendicular distance from the mechanical ax(cid:173)
`is line to the center of the knee joint line. The frontal plane
`mechanical axis of the lower limb is the line from the center
`of the femoral head to the center of the ankle plafond. The
`normal mechanical axis line passes 8 ± 7 mm medial to the
`center of the knee joint line.
`b Knee joint malorientation is present when the angle between
`the femoral and tibial mechanical axis lines and their respec(cid:173)
`tive knee joint lines (LDFA and/or MPTA) falls outside of
`normal limits (normal=87.5±2°).
`c Tibiofemoral mechanical alignment refers to the relation be(cid:173)
`tween the mechanical axes of the femur and tibia (normal=
`l.3° varus).
`d Tibiofemoral anatomic alignment refers to the relation be(cid:173)
`tween the anatomic axes of the femur and tibia.
`
`Shave et al., unpublished results 6.65 z 1 .4•
`
`anton.kurtz@gmail.com
`
`-11-
`
`

`
`Im CHAPTER 1 • Normal Lower Limb Alignment and Joint Orientation
`
`ing AP radiographs of the entire lower extremity on a
`single cassette (described in greater detail in Chap. 3), so
`that one can also assess the MAD.
`In the frontal plane, the line passing from the center
`of the femoral head to the center of the ankle plafond
`is called the mechanical axis of the lower limb (~ Fig.
`l -8a). By definition, malalignment occurs when the cen(cid:173)
`ter of the knee does not lie close to this line. Although
`normal alignment is often depicted with the mechanical
`axis passing through the center of the knee, a line drawn
`from the center of the femoral head to the center of the
`ankle typically passes immediately medial to the center
`of the knee. Moreland et al. ( 1987) reviewed long stand(cid:173)
`ing AP radiographs of both lower extremities in 25
`normal male volunteers and documented that the center
`points of the hip, knee, and ankle are nearly collinear.
`The angle between the mechanical axis of the tibia and
`femur (tibiofemoral angle) was 1.3±2° varus (~ Fig.
`l -8c). A commonly measured value is the anatomic ti(cid:173)
`biofemoral angle. This is usually approximately 6° val(cid:173)
`gus (~ Fig. l-8d). Hsu et al. (1990) reviewed long stand(cid:173)
`ing AP radiographs of the lower extremity of 120 normal
`volunteers of various ages and reported that the me(cid:173)
`chanical axis generally passes immediately medial to the
`center of the knee. In their population, the mechanical
`tibiofemoral angle measured 1.2±2.2° varus. In a study
`of 50 asymptomatic French women older than 65 years
`(Glimet et al. 1979), the mechanical tibiofemoral angle
`measured 0°. Most recently, Bhave et al. (unpublished re(cid:173)
`sults) studied a group of 30 adults older than 60 years, all
`of whom had no history or evidence of injury, surgery,
`arthrosis, or pain in their lower extremities. The me(cid:173)
`chanical tibiofemoral angle measured 1.3± 1.3°.
`The distance between the mechanical axis line and
`the center of the knee in the frontal plane is the MAD.
`The MAD is described as either medial or lateral. Medi(cid:173)
`al and lateral MADs are also referred to as varus or val(cid:173)
`gus malalignments, respectively. In a retrospective study
`of25 knees in adult patients of different ages, the normal
`MAD was 9.7±6.8 mm medial (Paley et al. 1994) (~ Fig.
`l -8a). In a recent prospective study of normal lower
`limbs in people older than 60 years without any evidence
`of pathological abnormality of the knee, the MAD was
`4.1 ±4 mm (Bhave et al., unpublished results).
`
`Hip Joint Orientation
`
`Previously, hip joint orientation was evaluated using the
`neck shaft angle (NSA). The normal NSA is 125°-131°.
`In an anatomic study of isolated cadaver femora, Yoshi(cid:173)
`oka et al. {1987) determined that the NSA in adult men
`normally measures 129° (~ Fig. 1-9). A line from the tip
`of the greater trochanter to the center of the femoral
`head was described by Paley and Tetsworth {1992) to de(cid:173)
`fine the orientation of the hip in the frontal plane. Chao
`
`Shave et al., unpublished results
`Paley et al .. 1994
`Yoshioka et al., 1987
`
`122 :1: 2.s·
`129.7 :I: 6.2°
`129°
`
`Fig.1-9
`Hip joint orientation in the frontal plane. MNSA according to
`different authors (mean± 1 standard deviation [SD]).
`
`Shave et al.. unpublished results 89.4 :1: 4.8°
`Chao et al., 1994
`94.6 :1: 5.5°
`89.9 :1: 5.2°
`Paley et al., 1994
`
`Fig.1-10
`Hip joint orientation in the frontal plane. LPFA according to
`different authors (mean ± 1 SD).
`
`anton.kurtz@gmail.com
`
`-12-
`
`

`
`CHAPTER 1 · Normal Lower Limb Alignment and Joint Orientation IDI
`
`Bhave et al., unpublished results
`Chao et al .. 1994
`Cooke et al., 1994
`Paley et al., 1994
`
`00.1 ± 1.s•
`88.1 ± 3.2·
`86 ±2.1·
`87.8±1.6·
`
`Bhave et al., unpublished results
`Chao et al .. 1994
`Cooke et al., 1994
`Paley et al .. 1994
`
`88.3± 2'
`87.5± 2.6·
`86.7± 2.3·
`87.2 ± 1.5°
`
`Fig.1-11
`
`Distal femoral knee joint orientation in the frontal plane.
`mLDFA according to different authors (mean± I SD).
`
`Fig.1-12
`Proximal tibial knee joint orientation in the frontal plane.
`MPTA according to different authors (mean ±I SD).
`
`et al. (1994) also measured the LPFA, which they called
`the horizontal orientation angle for the proximal femur,
`from long standing radiographs in 127 normal volun(cid:173)
`teers and stratified the study group according to age and
`gender. There was no significant change noted with age
`in women, and the relationship of this line to the
`mechanical axis of the femur measured 91.5±4.6° in
`younger women and 92. 7 ± 4.9° in older women. In men,
`the relationship of this line relative to the mechanical
`axis of the femur demonstrated an age-related tendency
`toward increasing varus, measuring 89.2 ± 5.0° in young(cid:173)
`er men and 94.6 ± 5.5° in older men. Data from our insti(cid:173)
`tution (Paley et al. 1994), based on a smaller group of 25
`asymptomatic adults, revealed that this proximal femo(cid:173)
`ral joint orientation line measures 89.9± 5.2°. Another
`study from our institution (Bhave et al., unpublished
`results) of asymptomatic older adults (>60 years) with(cid:173)
`out gonarthrosis revealed an LPFA of 89.4±4.8°. Based
`on these observations, we consider 89.9±5.2° to be the
`normal LPFA (Paley and Tetsworth 1992; Paley et al.
`1990, 1994) (• Fig. l-10).
`
`Knee Joint Orientation
`
`Regarding knee joint orientation, Chao et al. (1994} de(cid:173)
`termined that the distal femoral articular surface is nor(cid:173)
`mally in slight valgus relative to the femoral mechanical
`axis, measuring 88.1±3.2°. These results were confirmed
`by our data (Paley et al. 1994), with the distal femur in
`slight valgus relative to the mechanical axis of the femur
`(mLDFA=87.8± 1.6°). Cooke et al. (1987, 1994) obtained
`radiographs of the knee and hip after positioning the
`patient in a QUESTAR frame to improve reproducibility
`of the radiographic technique. In 79 asymptomatic
`young adults, the distal femoral orientation line mea(cid:173)
`sured valgus of 86±2.1°. In one study of older asymp(cid:173)
`tomatic adults (Bhave et al., unpublished results}, the
`LDFA was 88.l ± 1.5°. Based on all these studies, we con(cid:173)
`sider the normal mLDFA to be 87.5±2.5° (Paley et al.
`1994) (•Fig. 1-11).
`To consider the proximal tibial joint orientation,
`Chao et al. (1994) again stratified their data by age and
`
`anton.kurtz@gmail.com
`
`-13-
`
`

`
`Ill CHAPTER 1 • Normal Lower Limb Alignment and Joint Orientation
`
`a.
`
`gender and found a significant difference when compar(cid:173)
`ing older with younger men. In all groups, the proximal
`tibial joint orientation line measured slight varus rela(cid:173)
`tive to the mechanical axis of the tibia (S7.2±2.1°). In
`women, there was no age differential. In asymptomatic
`young men, there was slightly more varus (MPTA=S5.5
`±2.9°} compared with asymptomatic older men (87.5
`±2.6°). These data suggest that some young men with
`more varus later develop symptomatic degenerative ar(cid:173)
`throsis and "drop out" of the asymptomatic group of
`older men. This hypothesis is supported by data regard(cid:173)
`ing alignment of elderly normal lower limbs with no
`previous history of injury or surgery and with no evi(cid:173)
`dence of knee arthrosis or pain. One study ( Glimet et al.
`1979) of 50 elderly asymptomatic French women docu(cid:173)
`mented that the mechanical tibiofemoral angle in this
`select group measures 0° instead of slight varus as is
`seen in the normal population. The second study, from
`our institution (Bhave et al., unpublished results), dem(cid:173)
`onstrated an MPTA of SS.3 ± 2° in patients older than
`60 years. Cooke et al. (1994) reviewed standardized ra(cid:173)
`diographs obtained using a positioning frame and
`found that the MPTA is S6.7±2.3°. These results were
`confirmed by our data (Paley et al. 1994}, with an MPTA
`of 87 .2° varus ± 1.5°,