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Kyle N. Kunze, MD Orthopaedic Sports Medicine Surgeon Cartilage Restoration · Joint Preservation Hip · Knee · Shoulder · Regenerative Medicine

Conditions & Care

Knee Conditions

ACL tears, meniscus injuries, cartilage damage, and knee arthritis — evaluated and treated with an emphasis on returning patients to full activity.

Knee Conditions

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Anatomy

Condition

Classifications

Schenck (anatomic) classification

The Schenck classification is the system most often used for knee dislocations because it describes which ligaments are torn rather than the direction of displacement, which is frequently unknown by the time the knee is examined. It guides both the urgency and the surgical plan. Two modifiers are added to any grade: C for an arterial (vascular) injury and N for a nerve injury — most often the common peroneal nerve.

Grade	Structures involved	What it means clinically
KD I	One cruciate torn, with one or both collateral or corner structures	A multiligament injury in which one cruciate is intact; often treatable with a single-stage reconstruction of the torn structures
KD II	Both ACL and PCL torn, collaterals intact	Uncommon in practice; requires reconstruction of both cruciates with tunnels planned to avoid convergence
KD III-M	ACL, PCL, and the medial side (MCL and posteromedial corner)	The most common pattern; medial structures are addressed early, with cruciate reconstruction in the same setting or staged
KD III-L	ACL, PCL, and the lateral side (LCL and posterolateral corner)	Carries the highest rate of peroneal nerve injury and warrants close vascular assessment; the corner is anatomically reconstructed rather than repaired
KD IV	ACL, PCL, and both the medial and lateral sides	The highest-energy pattern, with the greatest risk of vascular and nerve injury and the most complex staged reconstruction
KD V	Multiligament injury with a periarticular fracture (fracture-dislocation)	Fracture fixation takes priority, with ligament reconstruction planned once the bone has healed and motion is restored

A KD III-L or KD IV injury, or any grade with a C or N modifier, is treated as a limb-threatening problem: ankle–brachial index measurement and CT angiography are obtained urgently, and vascular repair precedes any ligament surgery.

By tear pattern

Longitudinal (vertical) tears run parallel to the circumferential collagen fibers, most often in the peripheral third. Because the fibers that carry hoop stress remain intact and the blood supply is good, these are the most repairable tears — commonly seen in younger patients and alongside ACL injuries.

Bucket-handle (displaced longitudinal) tears are long vertical tears in which the inner fragment flips into the joint, classically causing a locked knee that will not fully straighten. These are urgent to address and are usually repairable if reduced early, since the torn segment is typically peripheral.

Radial tears run perpendicular to the collagen fibers, from the inner free edge outward. They cut across the hoop-stress fibers, so even a small radial tear can substantially compromise the meniscus's ability to distribute load. Historically trimmed, radial tears are now increasingly repaired — often with a side-to-side or transtibial technique — when they extend into vascular tissue, because meniscectomy in this pattern significantly raises contact pressures.

Root tears are avulsions or radial tears within roughly one centimeter of the meniscal root attachment on the tibia. The root anchors the meniscus, so a root tear allows the whole meniscus to extrude out of the joint — biomechanically equivalent to a total meniscectomy. They present as posterior knee pain, sometimes without a clear injury, and are frequently missed on MRI unless specifically sought (a "ghost meniscus" sign or extrusion on coronal images). Repair, typically transtibial pull-out fixation, is favored in patients without established bone-on-bone arthritis.

Ramp lesions are tears at the meniscocapsular junction or the meniscotibial ligament of the posteromedial corner, at the back of the medial meniscus. They occur in 20–40 percent of ACL tears, add to rotational and anterior instability, and are easily missed — they require a dedicated posteromedial arthroscopic view to see. Recognizing and repairing a ramp lesion at the time of ACL reconstruction reduces residual laxity and graft strain.

Horizontal cleavage tears split the meniscus into upper and lower leaves. They are typically degenerative, common in older patients, and often asymptomatic; treatment favors nonoperative care, with selective trimming or repair of the affected leaf if truly symptomatic.

Flap (parrot-beak) tears combine radial and longitudinal components, producing a mobile flap that can catch in the joint. Mechanical symptoms are common, and treatment usually means trimming the unstable flap while preserving the healthy rim.

Complex and degenerative tears combine several patterns in tissue of poor quality, most often in the setting of existing cartilage wear. These are generally treated nonoperatively first; surgery is reserved for genuine mechanical symptoms rather than pain alone.

By location and blood supply

Red–red (outer third) — well vascularized; the best healing potential and the strongest indication for repair.

Red–white (middle third) — partial blood supply; repairable in many patients, particularly younger ones or when biologic augmentation is used.

White–white (inner third) — avascular; unlikely to heal, so an unstable fragment here is usually trimmed.

Tears are also described by the zone involved — anterior horn, body, posterior horn, or root — and by which meniscus is affected. Medial tears are more common and more often degenerative; lateral tears are more often traumatic and associated with ACL injury and with discoid variants.

Other features that change the plan

Stability and displacement — whether the fragment can be displaced with a probe at arthroscopy, and by how much, determines whether it needs treatment at all.

Acute versus chronic and tissue quality — acute tears in healthy tissue heal predictably; chronic, frayed, or deformed tissue heals less reliably.

Meniscal extrusion — the meniscus displaced outside the joint margin, most often with root tears or degeneration, signals loss of load-sharing function even when the tear itself looks small.

Discoid meniscus — a congenitally thickened, disc-shaped meniscus (almost always lateral) that tears more readily in adolescents and is treated by reshaping (saucerization) with repair of any unstable rim rather than removal.

Risk Factors / Causes

Symptoms

Diagnosis

Non-Surgical Treatment ▾

Surgical Treatment ▾

Dr. Kunze’s approach to ACL surgery

There is no single ACL operation that is right for everyone. Dr. Kunze treats each patient individually, building the plan around your goals, your activity level and the sports you want to return to, your age and anatomy, and the specific pattern of the tear on imaging and examination.

A central part of that decision is whether the ACL can be repaired — preserving your own ligament when the tear pattern and tissue quality allow it — or whether it should be reconstructed with a graft. When reconstruction is the right answer, graft choice is discussed with you rather than applied by default, and additional procedures such as a lateral extra-articular tenodesis or meniscus repair are added when they lower the risk of re-injury.

Dr. Kunze’s approach to knee arthritis surgery

The central question in arthritis surgery is how much of the knee actually needs to be replaced. For an active patient with bone-on-bone arthritis confined to a single compartment and intact ligaments, Dr. Kunze favors replacing only that compartment. A partial knee replacement preserves the patient’s own ACL, PCL, and unaffected cartilage, and tends to feel more natural with better range of motion than a total replacement.

A good-quality MRI is always obtained to confirm that the other compartments are healthy before a partial replacement is recommended, because the trade-off of a partial is that an unreplaced compartment can wear over time and eventually require conversion to a total. When arthritis involves two or three compartments, or the ligaments are deficient, a total knee replacement is the more reliable and durable answer.

In either operation, robotic-assisted (MAKO) technique is used to improve the precision of implant positioning from a CT-based 3D plan. Younger patients with early or malaligned arthritis are also evaluated for joint-preserving alternatives — osteotomy or cartilage restoration — before replacement is considered.

Dr. Kunze’s approach to meniscus surgery

Dr. Kunze will critically evaluate your MRI to determine the tear pattern and tissue quality. If possible and when aligned with your goals, Dr. Kunze will attempt to preserve your meniscus as opposed to simply removing the torn piece to promote the longevity and health of your knee. Meniscus preservation is always a priority because removing torn meniscus tissue will accelerate arthritis. This is especially true for younger, active patients when tears occur in locations especially poised to heal. Meniscus allograft transplantion is a procedure reserved for younger patients with a previously resected or irreparable meniscus with preserved cartilage and pain directly localized to the compartment where the meniscus is compromised.

If a meniscus tear must be trimmed out (partial meniscectomy), then Dr. Kunze makes every attempt to preserve as much remaining health meniscus tissue as possible. Partial meniscectomy is reserved only for irreparable complex, radial, or degenerative tears with mechanical symptoms or a low likelihood of healing.

During the consultation, the whole knee is evaluated and attention is not simply directed only to the meniscus tear. If you have meniscus deficiency alongside other conditions, such as malalignment, ligament instability, or cartilage defects, Dr. Kunze addresses these issues as well in order to optimize the longevity of your native knee. For example, a meniscus transplant may be performed alongside a realignment procedure or cartilage procedure to make sure the meniscus transplant has a healthy environment to heal and suceed.

Repair versus removal versus transplant

The right operation depends on the tear pattern, where it sits relative to the blood supply, and how much healthy meniscus remains.

Approach	Best suited for	What happens to the meniscus	Weight-bearing after surgery	Return to sport
Meniscus repair	Vertical, bucket-handle, or peripheral tears in the blood-supplied outer “red zone,” root tears, and ramp lesions — especially in younger, active patients and alongside ACL reconstruction	The tear is sutured so it heals and the meniscus is kept	Protected in a brace with crutches for roughly 4–6 weeks, depending on the tear	About 4–6 months
Partial meniscectomy	Complex, radial, or degenerative tears and tears in the avascular inner “white zone” that cannot heal, with true mechanical symptoms such as catching or locking	Only the unstable fragment is trimmed; the healthy rim is preserved	Full weight-bearing immediately	About 4–6 weeks
Meniscus allograft transplantation	Younger patients with a previously removed meniscus who develop activity-related pain and swelling, with intact ligaments and preserved cartilage — before bone-on-bone arthritis develops	The missing meniscus is replaced with size-matched donor tissue	Protected in a brace with crutches for about 6 weeks, often followed by a period in an unloading brace	About 6–9 months

Why preserving the meniscus matters: it distributes load across the joint and protects the cartilage. Removing more tissue than necessary raises contact stress on the cartilage and can accelerate arthritis — which is why repair is favoured whenever the tear pattern and tissue quality allow it, and why transplantation is offered to selected patients before arthritis sets in.

Risks to understand

Meniscus surgery is common and generally well tolerated, but it carries risks worth weighing before deciding: infection, blood clots, knee stiffness, a repaired or transplanted meniscus that does not fully heal and may re-tear, and progression of arthritis over time — particularly when meniscal tissue has been removed. Because repair and transplantation depend on biological healing, a second procedure is occasionally needed if the tissue fails to heal. Overall, these procedures are designed to reduce pain, relieve mechanical symptoms, and protect the cartilage, and outcomes differ on a patient by patient basis.

Follow-up and long-term outcomes

Partial meniscectomy. Full weight-bearing immediately, with early therapy aimed at swelling control and quadriceps activation; running at around 4 weeks and recreational sport at 4–6 weeks. Desk work is often possible within a few days.

Meniscus repair. Protected weight-bearing in a brace with controlled motion for 4–6 weeks, progressive loading from 6–12 weeks, and return to sport at about 4–6 months while the tear heals.

Meniscus transplantation. Brace and crutches for about 6 weeks, frequently followed by a period in a compartment-unloading brace, then phased therapy over 6–9 months before impact activity.

Choosing the osteotomy: where the correction is made

All three operations realign the leg or the kneecap by making a precise cut in bone and holding it in a corrected position with a plate and screws. Which bone is cut depends on where the deformity actually originates, which compartment is overloaded, and whether the problem is limb alignment or kneecap tracking. Full-length standing alignment X-rays and, in kneecap cases, a CT or MRI measurement of tubercle position are obtained before planning.

Procedure	Where the cut is made	What it corrects	Who is a candidate	Often combined with
High tibial osteotomy (HTO)	Upper tibia, below the joint line	Bow-legged (varus) alignment originating in the tibia; shifts load off the inner (medial) compartment. Slope can also be adjusted in ligament-failure cases.	Younger, active patients with medial-compartment pain or cartilage loss and varus alignment coming from the tibia, good motion, and a stable knee or a planned ligament procedure — too young or too active for replacement	Medial cartilage restoration, meniscus repair or transplant, ACL or PCL reconstruction
Distal femoral osteotomy (DFO)	Lower femur, above the joint line	Knock-kneed (valgus) alignment originating in the femur; shifts load off the outer (lateral) compartment	Patients with lateral-compartment pain or cartilage loss and valgus alignment arising in the femur, with reasonable motion and no widespread arthritis	Lateral cartilage restoration, lateral meniscus transplant, ligament reconstruction
Tibial tubercle osteotomy (TTO)	The bony bump on the front of the tibia where the patellar tendon attaches	Kneecap tracking and load, rather than limb alignment — the tubercle is moved inward, forward, or downward to recentre the patella and unload it	Patients with recurrent kneecap instability or kneecap-area pain and cartilage wear whose measurements show a laterally positioned tubercle or a patella riding high; also used to protect a kneecap cartilage repair	MPFL reconstruction, patellofemoral cartilage restoration, trochlear procedures

Common to all three: correction is planned from standing alignment films, fixed with a plate and screws, and protected with a period of limited weight-bearing while the bone heals — typically around six weeks before progressive loading, with return to sport later than a soft-tissue-only operation. Smoking and poorly controlled diabetes meaningfully impair bone healing and are addressed before surgery.

If the plate becomes bothersome or irritating, it can be taken out safely once the osteotomy site has healed.

Surgical options for knee arthritis

Who is a candidate

The procedure

Partial versus total knee replacement

The right operation depends on how many compartments are arthritic, the condition of the ligaments, and how active you are. A partial replacement preserves healthy tissue when only one compartment is involved; a total replacement is the durable answer for arthritis spread across the knee.

Option	Best suited for	What is preserved	Recovery pace	Expected lifespan
Partial (unicompartmental) knee replacement — MAKO robotic-assisted	Bone-on-bone arthritis confined to one compartment, with intact ACL and PCL and healthy remaining compartments	Your own ligaments and the unaffected compartments; usually feels more natural than a total replacement	Walking the day of surgery; walker or crutches for comfort and stability at first, typically a cane within 1–2 weeks	Designed to last 10–20 years, after which it can be converted to a total knee replacement
Total knee replacement	Arthritis affecting two or three compartments, or a knee with a deficient ACL or significant deformity	Resurfaces all compartments; the most reliable option for widespread arthritis	Similar milestones to a partial replacement but slower, with more emphasis on regaining motion	Designed to last 25 years or more

Why the distinction matters: a partial replacement leaves your own ligaments and healthy cartilage in place, which most patients find feels closer to a natural knee — but it only works when the arthritis truly is confined to one compartment, which is why high-quality imaging of the other compartments is obtained before it is recommended.

Follow-up and long-term outcomes

Partial knee replacement. Walking the day of surgery with a walker or crutches, a cane within 1–2 weeks, driving by about 4 weeks (sooner for a left knee), and recreational activity such as golf, tennis, and skiing in moderation by 3–6 months. Implants typically last 10–20 years before a possible revision to a total replacement.

Patellofemoral replacement. A timeline similar to a medial or lateral partial replacement, with additional early attention to quadriceps strength and kneecap tracking.

Total knee replacement. Walking with assistance the day of or after surgery, off assistive devices over several weeks, and continued gains in strength and motion for 6–12 months. Modern implants are designed to last 25 years or more.

Follow-up visits track motion, strength, and implant position with periodic X-rays. Longevity and outcome depend on which compartments were involved, alignment, body weight, activity level, and how closely the rehabilitation protocol is followed.

Graft Choices ▾

Recovery & Return to Sport ▾

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Disclaimer: All materials presented on this website are the opinions of Dr. Kyle Kunze and any guest writers, and should not be construed as medical advice. Each patient’s specific condition is different, and a comprehensive medical assessment requires a full medical history, physical exam, and review of diagnostic imaging. If you would like to seek the opinion of Dr. Kyle Kunze for your specific case, we recommend contacting our office to make an appointment.