Effects of Midcarpal Arthrodesis on Wrist Coupling and Performance
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Garg, R ; Kraszewski, A ; Stoecklein, H. ; Backus, S. ; Lenhoff, M. ; Wolff, A. ; Hillstrom, H ; Wolfe,
S.W1, 2
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Hospital for Special Surgery, NY, USA
Weill Cornell Medical College, NY, USA
email: [email protected]
INTRODUCTION
A
composite
wrist
motion
of
radial
deviation/extension to ulnar deviation/flexion has
been termed the “dart thrower’s motion” and is
thought to be important to many activities requiring
force and accuracy [1,2]. There is little information
concerning the relationship between functional
performance and wrist “coupling [3],” the amount
of flexion-extension per degree of radial-ulnar
deviation. The purpose of our study is to compare
wrist coupling and functional performance between
healthy subjects, healthy splinted subjects, and
those who have undergone midcarpal arthrodesis.
We hypothesize that altered wrist coupling will
result in diminished performance.
METHODS
Eighteen reflective markers were fixed to the upper
extremity, trunk, and pelvis of ten healthy males
and ten males who had undergone midcarpal
arthrodesis of their dominant wrist. Each healthy
subject performed 15 dart, basketball and football
throws, and hammered 15 nails with and without a
hinged splint that constrained radial-ulnar deviation
(RUD). Each arthrodesis subject performed these
tasks without a splint. Three-dimensional angular
excursions of the wrist were acquired at 200Hz with
a 12-camera Motion Analysis system (Santa Rosa,
CA). The wrist joint coordinate system was
implemented in Visual3D (Germantown, MD) to
calculate angles. Dart and football throwing
performance was measured as the distance to the
target’s center. A graduated scoring system was
used for basketball accuracy. Hammering
performance was measured by time taken to drive a
nail flush, total number of strikes, and ratio of
missed strikes to total number of strikes. Coupling
was expressed as angles using the arctangent2
function (e.g. -45° indicates 1:1 coupled FE and
RUD). Paired and unpaired t-tests were used to
compare coupling values and performance for
healthy, splinted and arthrodesis subjects.
RESULTS AND DISCUSSION (Table 1)
Wrist coupling and performance were significantly
reduced by splinting in dart throwing, basketball
throwing and hammering for healthy subjects.
Wrist coupling was also reduced for football
throws, however, no difference was found in
performance by splinting. Performance was
significantly different between healthy (free
condition) and midcarpal arthrodesis subjects for all
the tasks, except football. Wrist coupling was also
reduced for all tasks in arthrodesis subjects,
however, it reached statistical significance only for
basketball throwing.
CONCLUSIONS
Constraining radial-ulnar deviation results in
diminished wrist coupling during functional tasks.
Diminished wrist coupling can result in reduced
functional performance in several tasks that require
both accuracy and force. Surgical and rehabilitative
efforts should be focused on the restoration of wrist
coupling following injury.
REFERENCES
1.
Palmer AK, Werner FW, Murphy D,
Glisson R. Functional wrist motion: a
biomechanical study. J Hand Surg [Am]. 1985
Jan; 10(1): 39-46..
2.
Werner FW, Green JK, Short WH, Masaoka
S. Scaphoid and lunate motion during a wrist dart
throw motion. J Hand Surg [Am]. 2004 May;
29(3): 418-22
3. Li ZM, Kuxhaus L, Fisk JA, Christophel TH.
Coupling between wrist flexion-extension and
radial-ulnar deviation. Clin Biomech (Bristol,
Avon). 2005 Feb; 20(2): 177-83.
.
Table 1. Performance and coupling measures for dart throwing, hammering, basketball and football throwing
tasks averaged across ten healthy (free and splinted) and ten midcarpal arthrodesis subjects.
Dart
Hammering
Basketball
Football
Throwing
Throwing
Throwing
Coupling
Perf
Coupling Time
# of
%
Coupling Perf Coupling Perf
(°)
(mm)
(°)
(sec)
strikes missed
(°)
(0-5)
(°)
(mm)
Free(F) -64.3°
-80.7°
69
-59.7°
2.4
4.8
5%
-73.0°
3.9
155
Splinted(S) -78.3°
103
-75.9°
3.5
6.3
9%
-85.0°
3.5
-89.3°
159
Midcarpal -74.5°
133
-63.8°
9.0
17.2
6%
-80.5°
2.8
-98.2°
166
Arthrodesis
(MA)
F vs. S p 0.0001
0.012
0.0001
0.044
0.001
0.029
0.013
0.137
0.119
0.722
F vs. MA p 0.081
0.0001
0.0001 0.0001 0.593
0.046
0.042
0.314
0.129
0.622
Note that a coupling value closer to -45° indicates a more coupled motion.
Performance (Perf): Dart Throwing: Distance (mm) of dart from the target center
Hammering: Time (sec) taken per nail # of strikes to drive the nail flush. Ratio of missed
to the total no of strikes per nail.
Basketball Throwing: 5 points for every ball sunk, 2 points for hitting either front or
back of the rim, 1 point for hitting the side of the rim, and 0 for missing the rim altogether
Football Throwing: Distance (mm) from the center of impact to the center of the target