Pure Motion
WHAT IS A PURE MOTION KNEE REPLACEMENTSM?
A Pure Motion Knee is Dr. W. Gaines Cumbie’s refined approach to knee replacement surgery, defined by three required principles that are applied in every case:
- Medial oblique incision - Placed on the inner side of the knee to reduce tension and discomfort across the front of the knee during bending
- Muscle- and tendon-sparing approach - Designed to support a smoother, faster early recovery
- Patient-specific implant positioning - Designed to restore each patient's unique pre-arthritic alignment and joint line, with the goal of more natural motion after knee replacement
Together, these principles are intended to support knee motion that more closely resembles how the knee moved before osteoarthritis caused pain, stiffness, and loss of function.
PRINCIPLE #1: MEDIAL OBLIQUE INCISION
In a Pure Motion Knee, the skin incision is placed in a medial oblique orientation rather than directly over the front of the knee.
This placement is designed to avoid putting the incision at the point of maximal tension when the patient bends the knee. By positioning the incision slightly off to the side, rather than directly over the front of the knee, this approach may also help reduce discomfort with kneeling after surgery for some patients.
Why patients may appreciate a medial oblique incision:
- The incision is not directly over the front of the knee at the point of maximal tension during bending.
- Positioning the incision off to the side may help reduce discomfort with kneeling.
- Incision placement is designed to better accommodate common knee motion after surgery.
PRINCIPLE #2: COMPLETE MUSCLE- AND TENDON-SPARING KNEE REPLACEMENT
In a Pure Motion Knee, the quadriceps muscle and tendon are left completely intact during surgical exposure.
Rather than cutting the quadriceps tendon, the muscle and tendon are gently mobilized to the side, preserving the knee’s extensor mechanism. This approach is intended to support early strength, stability, and confidence with movement after surgery.
Why patients often appreciate this muscle-sparing approach:
- Preservation of quadriceps strength may support earlier functional recovery
- Reduced irritation of the extensor mechanism may contribute to less early pain and stiffness
- Greater confidence with walking, physical therapy, and daily activities
- A smoother, more comfortable early recovery experience for many patients
PRINCIPLE #3: RESTORING THE PRE-ARTHRITIC JOINT LINE AND LIMB ALIGNMENT
A Pure Motion Knee also requires patient-specific implant positioning designed to restore the knee’s original joint line, axis of rotation, and limb alignment-the way the knee was oriented before arthritis developed.
Traditional knee replacement surgery often relies on standardized implant positioning applied to many patients. Research has shown that most people do not naturally have the same knee alignment. When a knee is reconstructed without regard to a patient’s native anatomy, the surrounding muscles, tendons, and ligaments may not function as they did prior to arthritis.
In contrast, the Pure Motion philosophy focuses on recreating each patient’s native knee anatomy. By restoring the pre-arthritic joint line and limb alignment, the knee is intended to move in a way that may feel more natural-allowing muscles, tendons, and ligaments to function in a manner that more closely resembles how they did before osteoarthritis and cartilage wear caused pain, stiffness, and restricted motion.
WHY MOTION MATTERS AFTER KNEE REPLACEMENT
Before arthritis, the knee moved smoothly and efficiently, with muscles, tendons, and ligaments working together in harmony. Osteoarthritis disrupts this balance and alters how forces travel through the joint.
A Pure Motion Knee is designed to address those changes by:
- Using a medial oblique incision positioned away from the front of the knee
- Preserving critical muscles and tendons
- Restoring the knee’s natural orientation
- Allowing supporting structures to function more similarly to how they did before arthritis
The goal is improved motion, improved function, and a knee that may feel more natural after replacement.
PURE MOTION VS. TRADITIONAL KNEE REPLACEMENT
Traditional Knee Replacement
- Often uses a midline incision directly over the front of the knee
- Often uses a standardized implant position for many patients
- Commonly involves cutting the quadriceps tendon to expose the joint
- When the knee is placed into a standardized position that differs from a patient’s natural alignment, ligaments may need to be cut or released to rebalance the knee, creating additional soft-tissue disruption in order to achieve stability
Pure Motion Knee ReplacementSM
- Uses a medial oblique incision rather than placing the incision directly over the front of the knee
- Preserves the quadriceps muscle and tendon during exposure
- Uses patient-specific implant positioning to closely restore the pre-arthritic joint line and limb alignment
- Aims to preserve natural muscle, tendon, and ligament function in support of more natural motion
A procedure cannot be considered a Pure Motion Knee ReplacementSM unless all three principles-medial oblique incision, complete muscle- and tendon-sparing surgery, and restoration of native alignment-are applied.
WHAT DOES THE RESEARCH SHOW?
Muscle-Sparing Surgical Approach
High-level studies, including systematic reviews and meta-analyses of randomized controlled trials, suggest that muscle-sparing subvastus approaches are associated with earlier return of quadriceps function, lower early pain scores, and improved early range of motion compared with traditional approaches. These early advantages have been reported without increased complication rates, and long-term outcomes appear similar between approaches.
Kinematic Alignment and Patient-Specific Implant Positioning
Multiple randomized trials and meta-analyses evaluating kinematic alignment have reported improved knee function scores, greater knee flexion, and longer walking distances before discharge when native alignment is restored. Other high-quality reviews demonstrate comparable long-term outcomes, highlighting the importance of patient anatomy, surgical execution, and alignment philosophy.
CPAK Classification and Knee Phenotypes
Research using the Coronal Plane Alignment of the Knee (CPAK) classification shows that most people do not have neutral knee alignment. Restoring a patient’s native alignment phenotype and joint line orientation has been associated with improved functional outcomes and patient satisfaction in selected groups.
WHY COMBINING ALL PURE MOTION PRINCIPLES MATTERS
The Pure Motion philosophy reflects published orthopedic research, surgical judgment, and an individualized approach to each patient’s unique anatomy:
- A medial oblique incision is designed to avoid placing the incision at the point of maximal tension and may help reduce discomfort with kneeling in some patients
- Muscle-sparing exposure may support better early recovery
- Restoring native alignment aims to support more natural knee mechanics
Pure Motion Knee ReplacementSM combines all three into one consistent philosophy-using a medial oblique incision, preserving the quadriceps mechanism, and restoring the knee’s original joint line and alignment. Together, this approach is intended to support early confidence, smoother recovery, and a knee that may move more naturally long-term.
WHAT MAKES PURE MOTION DIFFERENT FROM OTHER RAPID-RECOVERY KNEE REPLACEMENTS?
Some rapid-recovery approaches focus primarily on how the knee is exposed during surgery. While exposure technique matters, it is only one part of what determines how the knee functions afterward.
Two surgeons may use the same approach to expose the joint yet position implants very differently.
Pure Motion Knee ReplacementSM is different because it standardizes all three:
- A medial oblique incision designed to avoid the front of the knee at maximal flexion tension and potentially improve kneeling comfort
- A complete muscle- and tendon-sparing exposure intended to reduce soft-tissue disruption and support early recovery
- A defined, evidence-based implant alignment philosophy designed to restore the pre-arthritic joint line and limb alignment in support of more natural motion
PURE MOTION KNEE
More than muscle-sparing. Motion-restoring.
To learn whether Pure Motion Knee ReplacementSM is right for you, call to schedule an appointment with Dr. W. Gaines Cumbie or join one of his free educational virtual webinars.
FREQUENTLY ASKED QUESTIONS:
It is a knee replacement defined by three required principles: a medial oblique incision, a complete muscle- and tendon-sparing approach, and patient-specific implant positioning designed to restore the knee’s pre-arthritic joint line and limb alignment.
No. In a Pure Motion Knee ReplacementSM, the quadriceps muscle and tendon are preserved during surgical exposure.
The quadriceps muscle and tendon are an important part of the knee’s extensor mechanism and play a key role in knee stability, walking, stair climbing, and rising from a seated position. Preserving them may support early strength, stability, and confidence with walking and rehabilitation after surgery.
It means positioning the knee replacement implants based on the patient’s pre-arthritic anatomy rather than applying the same implant position to every knee. The goal is to support motion and soft-tissue function that more closely resemble the patient’s natural knee mechanics.
Traditional knee replacement often uses a midline incision, standardized implant positioning, and commonly cuts the quadriceps tendon.
Pure Motion uses a medial oblique incision, preserves the quadriceps, and uses patient-specific implant positioning designed to closely restore the knee’s pre-arthritic joint line and limb alignment.
Pure Motion is designed to reduce soft-tissue disruption and support early recovery. Many patients may experience less early pain and greater early confidence with movement, although recovery varies from one patient to another.
That is the goal. By preserving key soft tissues and using patient-specific implant positioning, Pure Motion is intended to support knee motion that may feel more natural for many patients after replacement.
Not necessarily. Candidacy depends on factors such as the patient’s anatomy, the severity of arthritis or deformity, prior surgery, and other clinical considerations. Dr. Cumbie evaluates each patient individually to determine the most appropriate surgical plan.
Pure Motion standardizes both the surgical approach (including incision placement and muscle sparing) AND how the implants are positioned.
By addressing both, the philosophy is intended to support early recovery while also promoting knee motion and function that may feel more natural over the long term.
