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| Because the MAS socket technology is designed to contain the ischial tuberosity and the ischial ramus, comfort, stability and gait are improved. Weight is distributed evenly over the soft tissue of the residual limb. | ||
An innovative, advanced socket design for transfemoral amputees is steadily gaining popularity with O&P practitioners and their patients. The Marlo Anatomical Socket design (MAS), developed by Marlo Ortiz, CP (M), Ortiz Internacional S.A. de C.V., Guadalajara Jalisco, Mexico, provides several advantages over the traditional socket design. Because the MAS socket technology is designed to contain the ischial tuberosity and the ischial ramus, comfort, stability and gait are improved. Weight is distributed evenly over the soft tissue of the residual limb. Ortiz describes this effect as a hydrostatic column because it avoids inappropriate pressures, improving the suction effect of the socket.
“True bone lock promotes stability and security during all phases of gait,” Ortiz told O&P World. “Consequently, the patient feels safe and secure. Moreover, proprioception is enhanced because the socket does not gap or shift in any direction.”
Typically, other socket designs force the wearer to compensate in some way due to lack of containment.
“With the MAS design, it is as if the socket is an integral part of the patient’s body,” said Ortiz.
Improved Functional Gait
One advantage of the MAS design is improved gait. Patients ambulate without lateral displacement of the trunk.
“Since the ramus is contained from heel contact to toe-off, no foot rotation occurs,” said Ortiz.
A wide base of support is not necessary while walking and normal arm swing is maintained. Functional gait is improved, the base gait is narrow and there is no lateral trunk bending. Lateral displacement of the center of gravity is also minimized.
The containment, said Ortiz, is as anteriorly on the ramus as possible, allowing for containment to be maintained throughout the gait cycle, as opposed to more posterior containment where the ischium can slip out of the socket at hip flexion.
Better Suspension
According to the Ortiz Internacional Web site, the use of auxiliary suspension belts is unnecessary with the MAS design. Instead, the prosthesis stays in total contact with the remaining limb by the use of suction valves, silicon, urethane or gel liners with distal or outer external suspension.
“The intimacy of the fit of the MAS design is unique,” said Ortiz
Enhanced Cosmesis
With the MAS design, cosmesis is greatly improved. Because the socket does not gap, it does not protrude.
“This enables us to hide all the trim lines around the socket,” said Ortiz. “The trim lines are virtually invisible, even with light fitting clothes.”
In traditional designs, the posterior trim lines include part of the buttock muscles. With the MAS, the height of the posterior wall to the gluteal fold is lowered, allowing the gluteus maximus to be completely out of the socket. The low trim lines also allow the femur to be placed into an over-adducted position, allowing the same angle of the sound leg, explained Ortiz.
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| (Left) The containment is as anteriorly on the ramus as possible, allowing for containment to be maintained throughout the gait cycle, as opposed to more posterior containment where the ischium can slip out of the socket at hip flexion. | ||
| (Right) An advantage of the MAS design is improved gait. Patients ambulate without lateral displacement of the trunk. A wide base of support is not necessary while walking and normal arm swing is maintained. | ||
Donning and Doffing
Because the weight bearing is shared along the surface of the residual limb, there is no skin breakdown or uncomfortable pressure.
“The containment walls do not distribute weight-bearing forces over the ramus and ischium,” said Ortiz.
Moreover, since there are no high proximal trim lines, donning and doffing are easier than the standard prosthesis.
Unrestricted Range of Motion
Additionally, the anterior and medial walls are lowered below the ischial level allowing for almost unlimited range of motion.
There are no restrictions on flexion, extension or rotation at the level of the hip, and the legs can be crossed up to 90° with no problems.
“Plus, the patient can sit comfortably on the buttocks, because there is no plastic material underneath,” Ortiz said.
The MAS total contact socket design has been fitted on more than 90 patients with various levels of transfemoral amputations. Patients differ in activity levels, ages, gender and types of suspension.
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