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MUSCLE-SPARING KNEE REPLACEMENT · MAKO® ROBOTIC · FRANKLIN, TN

Subvastus Approach Knee
Replacement in Franklin, TN

Quadriceps-Sparing Technique · Mako® Robotic Guidance · Dr. Cory Calendine, MD

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Call (615) 791-2630

The subvastus approach to knee replacement — also called quadriceps-sparing or SubV knee replacement — accesses the knee joint by elevating the vastus medialis muscle rather than cutting through the quadriceps tendon as traditional techniques require. Dr. Cory Calendine performs subvastus approach knee replacement at the Bone and Joint Institute of Tennessee in Franklin, TN, combining the muscle-sparing technique with Stryker Mako® SmartRobotics™ robotic-arm assisted guidance for precise implant positioning within the more confined surgical exposure. The result is a procedure that preserves the muscles controlling knee extension and stability — the muscles responsible for walking, climbing stairs, and recovering quickly — while delivering the same excellent long-term outcomes as standard knee replacement.

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ROBOTIC JOINT REPLACEMENT

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HOW THE SUBVASTUS TECHNIQUE DIFFERS FROM STANDARD KNEE REPLACEMENT

What Is the Subvastus Approach to Knee Replacement?

Surgical Access — Under the Muscle, Not Through It

Every knee replacement surgery requires a pathway to reach the joint. The standard approach — the medial parapatellar technique used in the vast majority of knee replacements performed worldwide — reaches the joint by making an incision through the quadriceps tendon, the thick tendinous structure connecting the powerful quadriceps muscle group to the kneecap. This incision is then repaired at the end of surgery and must heal. The healing process is part of why traditional knee replacement recovery involves a period of reduced quad function and the characteristic muscle weakness of the early weeks.

The subvastus approach takes a fundamentally different path. Rather than entering through the quadriceps tendon, the vastus medialis muscle — the teardrop-shaped muscle on the inner side of the thigh, just above the knee — is gently elevated from its attachment and lifted out of the way. The surgeon then works beneath it to access the joint directly, without any tendon incision. When the procedure is complete, the vastus medialis returns to its anatomical position. There is no tendon to repair and no muscle healing period. The extensors of the knee were never cut.

Medical illustration comparing the standard quadriceps tendon incision (red line) versus the subvastus approach entry route (green line) used in knee replacement surgery, showing muscle preservation with the subvastus technique.

Key Features of the Subvastus Approach

The clinical implications of this anatomical difference drive the recovery advantages that distinguish subvastus knee replacement from the standard technique:

  • Complete Quadriceps Preservation — No incision through the quadriceps tendon. The extensor mechanism remains structurally intact from the moment surgery ends.
  • Maintained Muscle Function — The vastus medialis returns to its native attachment with blood supply and nerve connections undisturbed.
  • Earlier Straight Leg Raise — Because the extensors were not cut, most patients can perform a straight leg raise sooner than after traditional knee replacement — a key early PT milestone.
  • Minimally Invasive Exposure — Smaller surgical corridor with complete joint visualization when performed by an experienced surgeon.
  • Reduced Soft Tissue Trauma — Less disruption to the structures surrounding the knee, contributing to reduced early post-operative pain and swelling.
Total Knee Replacement — Overview

THE SUBVASTUS ADVANTAGE

How Subvastus Compares To Standard Knee Replacement

Subvastus vs. Traditional Knee Replacement — How They Compare

Subvastus quadriceps-sparing approach compared with the traditional medial parapatellar approach to total knee replacement.
FactorSubvastus (Quadriceps-Sparing)Traditional (Medial Parapatellar)
Quadriceps tendonPreserved, no tendon incisionIncised and repaired, must heal post-operatively
Straight leg raiseSooner, often within daysDelayed while the extensor mechanism heals
Early pain levelsReduced: less tissue trauma in the first weekHigher in the first week due to tendon healing
Walker-to-cane transitionFasterStandard timeline: weeks 2 to 3
Long-term outcomes (6 months and beyond)EquivalentEquivalent
Mako robotic compatibilityYes, always combined in Dr. Calendine's practiceYes
Best suited forMost primary knee replacements, especially when early recovery is a prioritySevere deformity, revision, heavy scar tissue, or anatomy that limits muscle elevation
Medical illustration comparing two knee replacement surgical approaches side by side: the Medial Parapatellar (quadricep cutting) approach shown with a red incision line on the left, and the Subvastus or SubV (quadricep sparing) approach shown with a green incision line on the right, against a dark navy background.

The early recovery advantages of the subvastus approach are most pronounced in the first six to eight weeks following surgery. By the six-month mark, functional outcomes between approaches are equivalent. The subvastus technique’s value is in the quality and speed of that early recovery period — not in producing a better knee at two years. Both approaches produce an excellent knee replacement. The subvastus approach produces it with a more comfortable and faster path through the early weeks.

TOTAL KNEE REPLACEMENT BASICS

WHY THE SUBVASTUS APPROACH AND MAKO ROBOTIC GUIDANCE WORK TOGETHER

The Subvastus Approach Combined with Mako® Robotic Guidance

The subvastus approach creates a more confined surgical corridor than the standard medial parapatellar technique. This is the tradeoff of muscle preservation: the vastus medialis elevation limits the degree of lateral patellar eversion that is standard in traditional TKR, which means the surgeon works within a smaller exposure. In a surgeon’s hands without the appropriate experience and instrumentation, this limitation can affect the consistency of bone resection and component positioning. Mako® robotic guidance directly addresses this tradeoff.

Reproducible Results

Knee anatomy varies significantly from patient to patient — varus and valgus deformities, femoral bow, tibial plateau geometry, and soft tissue tension patterns all affect how a knee replacement is planned and executed. The combination of CT-based pre-operative planning and robotic intraoperative guidance provides consistent, reproducible component positioning across this range of anatomical variation. Each subvastus knee replacement achieves the same precision standard regardless of individual anatomical complexity.

Patient-Specific 3D Planning

Before surgery, a CT scan of the patient’s knee joint creates a three-dimensional digital model of that specific and unique anatomy. Dr. Calendine uses this model to plan the implant size, positioning, tibial slope, and component alignment in advance — adapted to the spatial constraints of the subvastus approach corridor. The plan is confirmed, adjusted if needed, and finalized before the patient arrives for surgery. On the day of the procedure, the robotic system executes that plan with guidance, not improvisation.

Enhanced Soft Tissue Protection

Soft tissue protection is the defining goal of the subvastus approach knee replacement technique. The robotic system’s pre-planned boundaries ensure that bone removal does not inadvertently expand into healthy tissue planes adjacent to the preserved vastus medialis muscle complex. The combination of subvastus surgical incision technique and robotic-assisted boundaries creates two independent layers of soft tissue protection — the approach itself, and the technology that keeps the resection within plan.

Precision Within Confined Space

The robotic arm’s AccuStop™ haptic boundary technology defines the pre-planned bone resection zone and provides tactile resistance if instruments approach the boundary. Within the smaller exposure of the subvastus approach, this haptic feedback replaces some of the visual reference points that are available in the wider exposure of traditional TKR. The result is that bone cuts executed within the subvastus corridor achieve the same reproducible accuracy as those performed through a wider approach — a meaningful technical advantage when working in a more restricted field.

Surgical Efficiency Maintained

The subvastus approach involves more technical complexity than standard TKR — the muscle elevation and the modified instrument technique require additional steps. The efficiency of Mako robotic guidance offsets this complexity. Real-time confirmation of bone cuts, immediate feedback on component positioning, and the elimination of guesswork from the resection process all reduce the steps that would otherwise extend operative time. The result is a total operative time comparable to standard knee replacement despite the added technical demands of the muscle-sparing approach.

Mako® Robotic-Assisted Joint Replacement

WHO IS A GOOD CANDIDATE FOR SUBVASTUS KNEE REPLACEMENT?

Is the Subvastus Approach Right for You?

The subvastus approach offers meaningful early recovery advantages for appropriately selected patients. Not every patient with knee arthritis is an ideal candidate for this technique, and the honest evaluation of candidacy is as important as the technique itself. Dr. Calendine’s evaluation process at BJIT assesses anatomy, deformity, prior surgery, body habitus, activity goals, and overall health to determine whether the subvastus approach is the most appropriate path for each individual patient.

Candidacy guide showing when the subvastus approach is well suited versus when the traditional medial parapatellar approach may be preferred for total knee replacement.
FactorSubvastus Approach (Well Suited)Traditional Approach (May Be Preferred)
Arthritis patternPrimary osteoarthritis, mild-to-moderate deformitySevere valgus deformity, complex revision cases
Prior knee surgeryNo prior TKR; minimal prior knee surgeryPrior TKR, significant adhesions, or scarring
Body habitusReasonable body habitus; good tissue qualityVery high BMI
Pre-op range of motionReasonable ROM; no severe flexion contractureSevere stiffness or significant flexion contracture
Activity goalsReturn to work or activity quickly; demanding lifestyleAny activity level: traditional TKR is not inferior

Ideal Candidates — Who Benefits Most

The patients who experience the greatest benefit from subvastus approach knee replacement are those for whom the early recovery timeline matters the most : working adults who need to return to a demanding job, travelers, caregivers, athletes who are accustomed to fast-paced rehabilitation, and anyone for whom the first six weeks of recovery represents a meaningful functional and personal priority. The long-term surgical results are often the same regardless of the specific approach used. The early weeks are where the subvastus difference is felt most directly for patients.

Anatomical and Technical Limitations

The subvastus approach requires specific training in the technique and experience managing the more confined surgical corridor. It is not appropriate for severe deformity cases where the wider exposure of the standard approach is needed for adequate visualization. Patients with prior knee replacement, extensive scar tissue, or anatomical variants that limit vastus medialis elevation may be better served by the traditional approach. Dr. Calendine evaluates each of these factors individually and provides direct guidance on which approach is appropriate for each patient.

Surgeon Experience — Why It Matters for SubV

The learning curve for the subvastus approach is well documented in the orthopedic literature. Surgeons adopting the technique show improvement in surgical efficiency and consistency across the first 50 to 100 cases. Dr. Calendine performs the subvastus approach as a primary technique for appropriate patients, not as an occasional variation. Combined with Mako robotic guidance that compensates for the reduced surgical exposure, his proficiency with the technique allows him to offer it to a broader range of patients than surgeons who perform it infrequently.

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WHAT RECOVERY LOOKS LIKE AFTER SUBVASTUS KNEE REPLACEMENT

Recovery Timeline — Subvastus Approach Knee Replacement

The Early Recovery Advantage in Practice

The recovery advantages of the subvastus approach are most tangible in the first six to eight weeks after surgery — the period when the preserved quadriceps function makes the most visible difference. Most patients are surprised by how quickly they can control and extend the knee, how much less pain they experience in the first week compared to their expectations, and how rapidly they progress through the milestones of early physical therapy. By six months, the functional outcomes between subvastus and traditional TKR are equivalent. The subvastus path to that outcome is demonstrably faster.

Div
Day of Surgery

Walking within hours of surgery. Quadriceps control preserved — most patients can perform a straight leg raise or begin early quad activation exercises the same day. Most go home same day.

Div
Week 1

Walker to cane for balance only. Typically less severe pain than patients expected based on accounts of traditional TKR. This facilitates optimal PT. Swelling being managed with elevation and ice. Waterproof dressing allows you to shower whenever you want.

Div
Weeks 2–3

Expect improved early knee flexion. Sleep quality improving as pain decreases. All stitches are under the skin. We will see you at 2 weeks to remove your bandage. Outpatient PT continues. **You can drive when you are walking steady with a cane and off narcotics.

Div
Months 1–2

Return to desk work earlier but nearly all jobs by 4–6 weeks. Stair climbing with confidence. Returning to the gym and full activity — gradually. PT continues until goals met.

Div
3–6 Months

Full functional recovery for most patients. Long-term outcomes equivalent to traditional TKR — excellent knee function, pain relief, and durability.

Knee Procedures at the Bone & Joint Institute of Tennessee

FREQUENTLY ASKED QUESTIONS

Frequently Asked Questions — Subvastus Knee Replacement

The Technique 

What exactly is the subvastus approach and how is it different from standard knee replacement?

In a traditional knee replacement, the surgeon gains access to the knee joint by making an incision through the quadriceps tendon — the strong tendon that connects the quadriceps muscle group to the kneecap. This approach, called the medial parapatellar approach, is reliable and widely used, but it does require dividing part of the tendon to open the joint. 

 

The subvastus approach takes a fundamentally different path. Rather than going through the tendon, the surgeon passes underneath the vastus medialis — the inner portion of the quadriceps muscle — leaving the entire quadriceps tendon and muscle completely intact. The joint is accessed by lifting the muscle from below rather than cutting through it from above. 

 

The result is a total knee replacement performed without any division of the quadriceps mechanism. In Dr. Calendine’s experience, this translates to faster early recovery of quad strength, a more comfortable initial recovery period, and outcomes that patients consistently describe as feeling more natural in the early weeks after surgery. 

This is one of the most common questions Dr. Calendine hears from patients considering subvastus knee replacement — and the answer genuinely surprises many of them. In a standard knee replacement, the incision runs straight down the center of the knee — directly over the front of the kneecap. It is a vertical midline scar that is prominently visible when the knee is flexed. 

 

With the subvastus approach, Dr. Calendine uses a medial oblique incision — meaning the incision runs at an angle along the inner side of the knee rather than straight down the front. Patients often describe it as the incision “coming in from the side” rather than going straight down the middle. This placement follows the natural path needed to pass underneath the quadriceps muscle rather than through it. 

From a cosmetic standpoint, many patients prefer the medial oblique scar — it sits away from the direct front of the knee, which is particularly noticeable when wearing shorts or kneeling. Functionally, patients also report less tenderness over the scar when kneeling after surgery compared to the standard midline incision. For patients who kneel regularly — whether for work, faith, or recreation — this can be a meaningful difference in daily life.

You may have come across the term “Jiffy Knee” in your research. Jiffy Knee is a federally trademarked brand name, and the surgical technique behind it is the subvastus approach — so there is a genuine connection worth understanding. 

 

Dr. Calendine is not a Jiffy Knee surgeon, and does not perform surgery under that brand. What he does perform is the subvastus approach — the same foundational muscle-sparing technique — combined with robotic precision using the Stryker Mako system. 

The distinction matters because the subvastus approach, while powerful on its own, has a known limitation: by preserving the quadriceps muscle entirely, the surgeon’s direct line of sight into the joint is reduced compared to the standard approach. Dr. Calendine believes that combining the subvastus technique with the Mako robotic system addresses this directly. The Mako system’s real-time three-dimensional guidance compensates for the reduced visual field by providing precise, data-driven confirmation of implant positioning throughout the procedure — something that is not built into technique-only approaches. 

 

The result is the muscle-sparing benefit of the subvastus approach with the precision assurance that robotics adds. That combination is what Dr. Calendine offers his patients. 

In Dr. Calendine’s view, yes — and the reason is directly tied to the technique’s one trade-off. 

 

The subvastus approach preserves the quadriceps muscle entirely, which is its greatest advantage. But that preservation also means the surgeon is working through a more limited visual window into the joint compared to a standard approach. In experienced hands, this is manageable — but it introduces a variable that precision technology can resolve entirely. 

 

The Stryker Mako robotic system creates a patient-specific three-dimensional model of the joint from a pre-operative CT scan. During surgery, the robotic arm provides real-time guidance so that implant positioning is verified continuously against that digital plan — not estimated through visual inspection alone. For the subvastus approach specifically, this means the reduced visual field is effectively offset by data-driven precision that does not depend on sight. 

 

The combination — muscle preservation through subvastus technique, implant precision through Mako robotics — is the approach Dr. Calendine believes gives patients the best of both. 

Am I a Candidate?

Who is a good candidate for the subvastus approach to knee replacement?

The subvastus approach is Dr. Calendine’s preferred technique for total knee replacement in patients whose anatomy supports it. Most patients who come to him for knee replacement are evaluated for subvastus candidacy as part of their consultation. 

 

The technique works best when the knee joint can be accessed adequately through the smaller surgical window the subvastus approach provides. Patients with relatively preserved joint anatomy, without significant structural complexity around the knee, are typically well-suited for this approach. 

 

A consultation with Dr. Calendine — including a review of your X-rays and a physical examination — is the only reliable way to determine whether the subvastus approach is appropriate for your specific knee. If it is not, Dr. Calendine will explain why and discuss what technique he would use instead. 

Yes. While the subvastus approach is Dr. Calendine’s preferred technique for knee replacement in appropriate candidates, it is not universally applicable. There are anatomic situations where the standard medial parapatellar approach is the better — or only — choice. 

 

The most common reasons a patient may not be a candidate for the subvastus approach include: large bone spurs (osteophytes) around the joint that limit access through the smaller surgical window, significant joint deformity that requires greater exposure to correct safely, and prior trauma or previous surgery around the knee that has altered the anatomy in ways that make the subvastus path less reliable. 

 

Revision knee replacement — surgery to replace a previously implanted joint — typically requires the medial parapatellar approach because the greater exposure it provides is necessary to safely address the existing implant and surrounding tissue. 

 

If you are not a candidate for the subvastus approach, Dr. Calendine will discuss exactly why and what approach he would use for your surgery. The goal in every case is the technique that gives you the best outcome — and sometimes that is the standard approach. 

Recovery & Results

How does recovery from subvastus knee replacement differ from standard knee replacement?
The most meaningful difference patients notice in the early weeks of recovery is quadriceps function. Because the subvastus approach leaves the quadriceps tendon and muscle completely intact, the quad is not recovering from any division or repair — it is recovering from the natural response to surgery around the joint itself.  In Dr. Calendine’s experience, patients who undergo the subvastus approach frequently demonstrate stronger early quadriceps activation compared to what is typical after a standard approach. This matters because quad strength is the primary driver of early functional recovery — the ability to straighten the knee fully, climb stairs, and get in and out of a chair all depend on it.  Physical therapy progresses along the same general timeline as standard knee replacement, but many subvastus patients find the early exercises feel more accessible. The knee responds earlier, and confidence in the leg builds faster. These are not dramatic differences in every patient — anatomy and individual healing vary — but they are consistent enough that patients who have had both a standard and  a subvastus replacement in different knees often prefer the subvastus recovery experience. 

Yes. Dr. Calendine performs subvastus knee replacement for patients from across Middle Tennessee and beyond. While his office and surgical facilities are located in Franklin, the majority of his patients travel from surrounding communities throughout the region. 

 

Patients regularly come to Dr. Calendine for subvastus knee replacement from Nashville, Brentwood, Murfreesboro, Spring Hill, Nolensville, Smyrna, Hendersonville, Mt. Juliet, Columbia, Antioch, Thompson’s Station, Gallatin, Belle Meade, Fairview, La Vergne, Arrington, College Grove, Leipers Fork, and communities throughout Middle Tennessee. Out-of-state patients are also welcome — the consultation process can begin remotely. 

 

If you are traveling for surgery, Dr. Calendine’s team can help coordinate your consultation and surgical scheduling to minimize the number of trips required.

FRANKLIN, TN · SERVING NASHVILLE, BRENTWOOD, SPRING HILL & MIDDLE TENNESSEE

Want to Know If the Subvastus Approach Is
Right for Your Knee? Start with a Consultation.

Schedule a consultation at the Bone and Joint Institute of Tennessee, 3000 Edward Curd Lane, Franklin, TN 37067. Dr. Calendine will evaluate your knee anatomy, review your goals, and give you a direct answer about whether the subvastus technique is appropriate for your situation. No referral required.

Schedule Appointment
Call (615) 791-2630