Technical Note: The Use of Step-Lock(TM) Knee Joints in Management of Wrist Flexion Contractures
Frank Searnati, C.P.
Introduction
The problem of managing contractures has long plagued the orthotic and prosthetic profession.
To date there have been numerous techniques used to correct contractures. Some have met with some success, others have not.
With the development of the Step-Lock? Knee Joints by Orthotic Technical Supply Co., the problem of controlling knee flexion
contractures was greatly reduced. The ratchet mechanism of the joint, along with the ease of utilizing the mechanism, either by a therapist
or patient, was truly a step in the right direction.
Recently, when confronted with a patient with a contracture of the wrist, it was decided to try to modify a Step-Lock? Knee Joint to
manage this type of flexion contracture.
Casting and Modification
Casting of the patient is done in the traditional manner, using elastic plaster bandage reinforced with an outer layer of non-elastic wrap.
Hold the patient's wrist in the most corrected position possible during the casting procedure. (Note: this particular patient also had a
fixed contracture of the MCP joint, and no attempt was made to correct this during the bracing procedure.)
Following completion of the casting, modify the positive model in the conventional
manner. Smooth the model, and add reliefs for the styloid and any other significant bony prominences.
Preparation of the Step-Lock? Joint and Uprights
Contour the uprights to the cast in a conventional manner (Figure 1)
.
However, one procedure that is critical to the bending process is the amount of upward bend given to the distal portion of the proximal
upright. It must be noted that since the Step-Lock? was designed to be used at the knee, it will only allow straightening to 1800. By
bending the proximal upright in an upward curve, the joint will then allow for normal wrist extension of approximately 300-350 (Figure 2)
.
Then add a palmar extension to maintain the palmar arch, and finally add a volar forearm band to the frame (Figure 3)
.
Lamination and Trimming Procedure
After the frame is completed, it is ready for lamination. Pull a PVA sleeve over the cast and apply three layers of nylon stockinette. Place
the metal frame on top of the stockinette and add three more layers of nylon over the frame. Finally, pull a single layer of Perlon®
stockinette over the cast to be used as a finishing layer. Stretch a PVA sleeve over the model and laminate the orthosis. (Note: Use a
mixture of 80% rigid 4110 polyester resin and 20% 4134 flexible resin. Add the flex to prevent the plastic from cracking and to add a degree of flexibility to the finished orthosis.)
After curing, trim the orthosis from the cast. Trim the laminate to follow the contours of the underlying frame. The one notable exception in the trimming procedure: leave a portion of the laminate on the dorsal
aspect of the orthosis just proximal to the wrist joint to create a dorsal band, thereby completing the three-point pressure system (Figure 4)
.
Results
The completed orthosis proved to be very effective. The Step-Lock? Joint allowed the
patient's wrist to be stretched into extension at approximate intervals of 30 Because of the ease of the locking mechanism, the patient could easily adjust the orthosis himself, thereby allowing
the contracture to be stretched at virtually any time during the day.
Conclusion
After using this technique on a number of other patients with similar wrist flexion con-
tractures, it has been concluded that the Step-Lock? Joint can be used very successfully in the management of a wrist flexion contracture. It has been found that the orthosis is extremely
functional, light weight, simple to use and cosmetically pleasing in appearance (Figure 5)
.
Acknowledgements
Orthotic Technical Supply, 1050 Northwest First Avenue, Bays 7-9, Boca Raton, Florida
33432 for Step-Lock? Knee Joints. Michael England, C.P.O., George Lambroussis, C.P.O., and Joseph Ruscito, Technician, for their help in the design and fabrication of this orthosis.
Frank Scarnati, C.P., is Vice-President of England Orthopedics, Inc., 239 Aven Street, Avenel, New Jersey 07001.
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