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9
4.5. Актуальные проблемы хирургии
UDK 372.2; 514; 539.13; 611.7; 616.072; 616.7; 617.3; 617.9
K. J. van Zwieten a, K. P. Schmidta, P. Adriaensens a, S. De Muntera, L. Kostena, O. E. Piskun b, S. A. Varzin b c
ASYMMETRIES AND INCONGRUENCES OF THE ARTICULAR SURFACES OF THE PROXIMAL INTERPHALANGEAL (P.I.P.) JOINT IN THE NORMAL HUMAN FINGER - ANATOMICAL OBSERVATIONS IN THE FRONTAL (CORONAL) PLANE
a) Department of Anatomy, University of Hasselt, Diepenbeek, Belgium, b) Department of Physical Culture and Adaptation, Peter-the-Great St. Petersburg Polytechnic University, St. Petersburg, Russia, c) Department of Intermediate Level Surgery, Faculty of Medicine, St. Petersburg State University, St. Petersburg, Russia.
koosjaap.vanzwieten@uhasselt.be
Abstract
By plane geometry graphical constructions, applied on a two-dimensional High Resolution MRI frontal (coronal) slice of the proximal interphalangeal (P.I.P.-) joint of an anatomical specimen of the normal human finger, we quantified the asymmetries and the incongruences of the mating joint surfaces. These allow fingers to perform additional movements, such as axial rotations. Our data may help to design close-to-reality P.I.P.-arthroplasties (artificial joints) for the treatment of osteoarthritis and rheumatoid arthritis.
Keywords PIP-joint; articular surfaces; graphical analysis; arthroplasties. Introduction
Some skeletal anatomy of the proximal interphalangeal joint of the finger is briefly recapitulated here. "The P.I.P.-joint of the human finger is composed by the convex caput (or head) of the proximal phalanx, articulating with the concave basis (or base) of the middle phalanx" [1]. Figure 1 represents the osteology of the index finger of the right hand. In this so-called anatomical position, the palmar side of this finger faces the viewer. By means of arrows, Figure 1 schematically indicates the (otherwise limited) axial rotations in the P.I.P.-joint, of the second phalanx with respect to the first phalanx.
Here, rotations are traditionally defined as supination, this is: the palmar side facing the viewer; and pronation, this is: the palmar side turning away from the viewer.
Fig. 1. Osteology of bones and joints of an otherwise normal index finger, right hand, palmar view. Main structures indicated by their anatomical terms.
State of the art
Figure 2 presents a dorsal view of the osteology of the same P.I.P.-joint. It also shows more details. A (red) asterisk indicates the trochlea, which is the pulley-shaped notch (or groove) between the ulnar condyle and the radial condyle of the head of the first phalanx. As is also visible in Figure 1, the ulnar condyle of the head of the first phalanx of the index finger is somewhat bigger than its radial condyle. As a matter of fact, this also applies to the mating condyles of the base of the second phalanx (Fig. 2). These structural peculiarities were described by [2] as follows. "The articular surfaces of the proximal interphalangeal joint show a slight asymmetry". With respect to other fingers, [3] helpfully specifies this, by stating: "In the coronal plane, the proximal phalanx of the index and long finger have a more prominent ulnar condyle. The ring and small finger have a more prominent radial condyle." [4] and [5] give corresponding and quantitative
observations, but mostly with respect to the condyles of the proximal phalanges. Furthermore, [2] notes the abovementioned pronation and supination of the P.I.P. - joint, suggesting that the specific movements are determined by various details of the mating skeletal elements of the joint, viz. the head of the first phalanx and the base of the second phalanx. In [6], these rotations are successfully quantified for each finger by the use of advanced technologies. Unfortunately however, [6] hardly reveals details of the joint's osteology, necessary to interpret such movements.
Fig. 2. Osteology of the P.I.P.- joint of an otherwise normal index finger, right hand, dorsal view. Asterisk indicates the trochlea, the pulley-shaped notch or groove between the condyles of the head of the first phalanx.
Research question
Our research question is twofold. First, we want to have a better impression of the asymmetry of both skeletal elements in the P.I.P. - joint, namely of the head of the first phalanx and the base of the second phalanx. As [2] rightly states, "the asymmetry of the condylar surfaces in the anteroposterior plane would require a profile projector to be analysed more accurately." Second, it is necessary to
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quantify the incongruences of each of the two convex condyles of the first phalanx in relation to their mating concave condyles of the second phalanx. This is even more pressing in light of recent publications on the design of artificial P.I.P.-joints (arthroplasties) [3, 7] to meet severe hand and finger destruction in rheumatoid arthritis (RA) and osteoarthritis (OA) [8, 9]. As [1] already successfully analysed the incongruences of the articular surfaces of the P.I.P. -joint in a sagittal plane, we here used an identical methodology, but now with regard to the frontal (or coronal) plane.
Material and methods
To obtain this profile projection of the anteroposterior (or frontal) plane suggested above, we used a detailed frame of a High Resolution MRI frontal (coronal) slice of the proximal interphalangeal (P.I.P.-) joint of an otherwise normal anatomical specimen of an extended right third finger. In diagram Figure 3a, the "blue plane" represents the slicing level. The length of the used frame is indicated by Technical data of the original HR MRI were: Varian 400 spectrometer, 9,4 T superconducting magnet. Field of view FOV (mm) in frontal plane: 25 x 25; imaging data matrix of 704 x 350; pixel resolution (^m) 71 x 71,5. Further acquisition parameters: repetition time TR: 2500 ms; echo time TE: 18 ms; number of averages NA = 24; slice thickness 2 mm. First the detailed frame (Fig. 3 b) was analysed with the help of a grid overlay [10] to get a quantitative impression of the asymmetry of both condyles at the head of the first phalanx, as well as of those at the base of the second phalanx. Then the original frame (Fig. 3 b) was used meeting requirements normally posed by plane geometry, to determine approximate radii of the curvatures of the mating articular surfaces. The tracing in Figure 3 c shows the outlines of these curvatures. In plane geometry [11], approximate radii of a curvature can be found through the points of intersection of the perpendicular bisectors of an inscribed open polygon formed by its successive chords (see Figure 4 b, facsimile of [11]). In view of the total number in this frontal slice, of 4 curvatures of articular surfaces to be analysed - namely those of the ulnar condyle of the first phalanx (convex) and the ulnar condyle of the second phalanx (concave), as well as those of the radial condyle of the first phalanx (convex) and the radial condyle of the base of the second phalanx (concave) - both pairs of surfaces were analysed separately. See respectively Figures 5 a and 5 b for the articular surfaces of the mating ulnar condyles, and Figures 6 a and 6 b for the articular surfaces of the mating radial condyles.
Fig. 4 a (left). Grid overlay [10], superimposed on detailed frame of Fig. 3b. Fig. 4 b (right). Approximate radii of a curvature can be found through the perpendicular bisectors of inscribed open polygon formed by its successive chords. Facsimile of the original publication [11].
Results
In Figure 4 a the grid [10] is superimposed on the original frontal slice of the P. I. P.- joint. The upper part of the image shows its ulnar condyles, the lower part shows its radial condyles. The curvature of the ulnar condyle of the first phalanx amounts about 5 squares, the curvature of the radial condyle about 4 squares. The same applies to the mating articular curvatures of the base of the second phalanx. In Figure 5 a the chords of the ulnar curvatures are plotted on the HR-MRI-slice, resulting in the inscribed open polygon C-J for the curvature of the articular surface of the first phalanx, and the inscribed open polygon K-T for the second phalanx. With mathematical computer graphics [12] we constructed the perpendicular bisectors of the chords of both curvatures. This resulted in points of intersection of these bisectors, respectively U, V, W, Z, and B1 for the ulnar (proximal) articular surface of the first
phalanx, and C1, E1, F1, H1, and J1 for the (distal) ulnar articular surface of the second phalanx. For clarity reasons, Figure 5 b shows only the geometry of the lines and the intersection points U - B1 (in red) and C1 - J1 (in green) Most "red" points lie closer to the first phalanx's articular curvature, than most "green" points do with respect to the second phalanx's articular curvature. It means that in the P. I. P.- joint the articular surface of the ulnar condyle of the first phalanx is more convex, in relation to its mating articular surface of the second phalanx. Thus, concerning the joint's ulnar condyles, there is some incongruence of the two articular surfaces, namely a greater convexity of the "ball" relative to a lesser concavity of its "socket", which allows additional (small) translations to occur here.
Fig. 5 a (top). HR-MRI-slice of Fig. 3 b, ulnar condyles with their inscribed polygons, perpendicular bisectors, and points of intersection, see text. Fig. 5 b (bottom). Derived from Figure 5 a, only geometry of lines and points of intersection U - B1 (in red) for 1st phalanx, and C1 - J1 (in green) for 2nd phalanx.
Fig. 6 a (top). HR-MRI-slice of Fig. 3 b, radial condyles with their inscribed polygons, perpendicular bisectors, and points of intersection, see text. Fig. 6 b (bottom). Derived from Figure 6 a, only the geometry of lines and points of intersection A1 - H1 (in red) for the first phalanx, and I1 - Q1 (in green) for the second phalanx.
In a similar way, graphical constructions were performed with respect to the curvatures of the radial condyles of the first phalanx and the second phalanx (Figs. 6 a - 6 b). The inscribed open polygon C-L of the proximal phalanx's articular curvature yielded the perpendicular bisectors' intersection points A1 - H1 (in red), while the perpendicular bisectors of the inscribed polygon M-Z of the second phalanx's articular curvature resulted in intersection points I1 - Q1 (in green). Most of the "green" points of intersection belonging to the first phalanx's articular curvature have more or less the same distance to their curvature as the "red" points of intersection have with respect to the second phalanx's articular curvature. This illustrates that in the P. I. P.- joint, the convex articular surface of the radial condyle of the first phalanx fits in nicely with its mating concave articular surface of the radial condyle of the second phalanx.
In other words, the two radial articular surfaces of both condyles of the P. I. P.-joint are fairly congruent, so that they approach a ball-and-socket - like situation. Therefore, apart from flexion and extension, axial rotation-like motions can occur here. However, lateral P. I. P.- motion is impossible in a normal human finger [2].
Conclusions
Recapitulating these results of our HR-MRI-slice of a P. I. P.- joint of an extended third finger, we state that (1) in frontal plane the ulnar condyles are somewhat greater than the radial ones, with a ratio of about five to four. We also note (2) a difference between congruences of the ulnar and the radial condyles. At the ulnar side the convexity of the condyle of the first phalanx's head is stronger than would be expected from the less curved mating concavity of the condyle of the second phalanx's base. At the radial side, however, the articular surfaces of the mating condyles of first and second phalanx rather show a ball-in-socket configuration.
The above two statements agree with other observations from literature [2-6]. Additional observations
With respect to (1), namely the quantified asymmetry of the ulnar and radial condyles of the P. I. P.- joint, there can be observed an accordance with some additional structures in our HR-MRI-slice. These are some of the associated soft tissues within the P. I. P.-joint, the so-called synovial folds or plicae that arise from the joint capsule. They are "embryological remnants of a synovial membrane that forms during normal develo pment" [13, 14]. Like the other synovial folds in the human body, they can also be visualised by MRI [14, 15]. Here they are
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recognised by their triangular appearance. In our HR-MRI-slice these synovial folds show a somewhat V-like and A-like form, respectively at the ulnar side (Fig. 7a) and the radial side (Fig. 7b) of the P. I. P.- joint. By our grid overlay [10] applied above, the sizes of these folds in the frontal HR-MRI-slice can be quantified, namely about 1 vs. 1,5 squares respectively (Figs. 7c and 7d). This implies that the greater condyles possess a smaller associated synovial fold, and vice versa. By their wedge-like forms, such soft tissues contribute to close-packed positioning of the structures, within synovial joints.
Left to right: Figures 7 a, 7 b, 7 c, and 7d, showing detailed views of Figure 3 b. Fig. 7 a. Synovial fold, V-like form, in P. I. P.- joint of the finger, ulnar side. Fig. 7 b. Synovial fold, A-like form, in P. I. P.- joint of the finger, radial side. Fig. 7 c. Synovial fold from Figure 7 a, quantified by grid overlay [10], see text. Fig. 7 d. Synovial fold from Figure 7 b, quantified by grid overlay [10], see text.
Discussion
Regarding (2), the identified incongruence and congruence in frontal plane of respectively the articular surfaces of the ulnar and the radial condyles, we can make some functional remarks on this configuration, with reference to [6] and [16]. Remarkably, the P. I. P.- pronation and - supination study [6] hardly refers to osteology, while the technically refined P. I. P. osteology measurements of [16] do not take into account P. I. P. - pronation and - supination. Moreover, our in situ data differ from this pure osteology study [16]. In [2] it is noted that P. I. P. - flexion is accompanied by supination. More or less in analogy to the knee joint, where flexion enables axial rotation [17], one might speculate about the location of such a center of rotation in the P. I. P. - joint too. The radial ball-in-socket configuration favors an axial rotation, while the ulnar incongruence creates space for translatory motions.
However this may be, each P. I. P. - joint of the fingers 2 - 5 exhibits its corresponding range of pronation and supination [6]. In the living this can be
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demonstrated, especially at full P. I. P.- flexion in which the various rotations result in directions of the fingers converging towards one point (Fig. 8) [18].
Fig. 8. "When the fist is clenched while the distal interphalangeal joints are still extended, the axes of the two distal phalanges of the four fingers converge at a point corresponding to the 'radial pulse'." After [18], adapted.
Summary
In a High Resolution (HR-) MRI frontal (coronal) slice of the proximal interphalangeal (P. I. P.-) joint of an anatomical specimen of the normal human third finger of the right hand, the asymmetry of the joint was quantified. Graphical analysis by means of plane geometry also revealed the incongruence of the mating articular surfaces of both ulnar condyles, and the congruence of the mating articular surfaces of both radial condyles of the P. I. P.- joint. This may be relevant for P. I. P.- axial rotations, namely pronation and supination. More research is needed to determine whether our conclusions are consistent. Acknowledgements
The authors wish to thank N. Fujihara MD PhD for her clear explanation and professional interest, and T. Gagnon of Gagnon Studio for his kind help.
References
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УДК 61:007+614.88
В.С. Белов, А.С. Воронин, А.И. Самаркин
АНАЛИЗ ЭФФЕКТИВНОСТИ ОКАЗАНИЯ СКОРОЙ МЕДИЦИНСКОЙ ПОМОЩИ ПРИ ДОРОЖНО-ТРАНСПОРТНЫХ ПРОИСШЕСТВИЯХ В Г.ПСКОВЕ (ПО ДАННЫМ 2017-2019 гг.)
Псковский государственный университет, Псков, Россия, kafmik@pskgu.ru
Резюме. Выполнен анализ эффективности оказания скорой медицинской помощи (СМП) при дорожно-транспортных происшествиях (ДТП) в г. Пскове. Мерами оценки эффективности работы станции СМП определены среднее время нахождения бригады СМП на выезде к месту ДТП с момента поступления вызова и 95%-й доверительный интервал его варьирования. Для анализа использованы данные Псковской станции СМП о вызовах на ДТП 2017...2019 годов.
