Adult Reconstruction
Anteromedial Approach to the Knee
Comprehensive guide to the anteromedial approach to the knee for FRCS exam preparation
Reviewed by OrthoVellum Editorial Team
Orthopaedic clinicians and medical editors • Published by OrthoVellum Medical Education Team
High Yield Overview
ANTEROMEDIAL KNEE APPROACH
Medial Parapatellar | TKA | MCL Access
MedialSide of approach
MPPMedial parapatellar
TKAMost common use
SaphenousNerve at risk
Variations
Medial Parapatellar
PatternMost common
TreatmentTKA standard
Subvastus
PatternMuscle sparing
TreatmentUnder vastus medialis
Midvastus
PatternSplit VM
TreatmentCompromise approach
Critical Must-Knows
- Medial parapatellar arthrotomy is standard for TKA
- Not a true internervous plane (through vastus medialis or around patella)
- Saphenous nerve and vein at risk with distal extension
- Pes anserinus landmark (sartorius, gracilis, semitendinosus)
- Evert patella for TKA exposure
Examiner's Pearls
- "Lateral retinacular release may be needed for patella eversion
- "Subvastus preserves extensor mechanism better theoretically
- "Saphenous nerve runs with great saphenous vein
- "Can extend distally along medial tibia
Critical Anteromedial Knee Approach Points
Medial Parapatellar
Standard TKA arthrotomy. Incision through or adjacent to vastus medialis insertion on patella. Then along medial patellar border and medial to patellar tendon.
Patella Eversion
For TKA, patella is everted laterally to expose joint. May need lateral retinacular release if tight. Subvastus avoids splitting quadriceps.
Saphenous Nerve/Vein
At risk with distal medial extension. Saphenous nerve accompanies great saphenous vein along medial knee and leg. Injury causes medial leg numbness.
MCL Access
The approach provides access to medial collateral ligament for repair or imbrication. Pes anserinus (sartorius, gracilis, semitendinosus) is landmark distally.
At a Glance
The anteromedial approach to the knee is the standard exposure for total knee arthroplasty (TKA), utilising the medial parapatellar arthrotomy. This is not a true internervous plane—the incision passes through or adjacent to vastus medialis. The patella is everted laterally to expose the joint; lateral retinacular release may be needed if tight. Variations include subvastus (muscle-sparing, passes under VM) and midvastus (splits VM). The saphenous nerve and great saphenous vein are at risk with distal extension—injury causes medial leg numbness. The pes anserinus (Sartorius, Gracilis, Semitendinosus—"Say Grace before Tea") is the key distal landmark providing access to MCL.
Mnemonic
SGSPes Anserinus Insertions
S
Sartorius
Most superficial
G
Gracilis
Middle
S
Semitendinosus
Deepest
Memory Hook:Say Grace before Tea (Sartorius, Gracilis, SemiTendinosus)!
Indications and Position
Indications:
- Total knee arthroplasty (most common)
- Unicompartmental knee arthroplasty
- Medial tibial plateau fractures
- MCL repair/reconstruction
- Medial meniscus surgery (open)
- Arthrotomy for infection
Patient Position: Supine with knee flexed to 90° over edge of table or supported.
Overview
Anteromedial Knee Approach Overview
The anteromedial approach to the knee provides versatile exposure for various knee procedures, from arthroscopic portals to open procedures including total knee arthroplasty.
Key Concepts:
- Standard approach for total knee arthroplasty (medial parapatellar variant)
- Not a true internervous plane - passes through or adjacent to vastus medialis
- Provides access to medial compartment, MCL, and medial meniscus
- Can be combined with other approaches for multiligament reconstruction
- Variations include subvastus and midvastus for TKA
Historical Context:
- Medial parapatellar arthrotomy described by Insall for TKA
- Subvastus approach developed to preserve extensor mechanism
- Midvastus represents compromise between exposure and muscle sparing
Anatomy
Surface Anatomy
Palpable Landmarks:
- Patella: Central reference point
- Patellar tendon: From inferior patella to tibial tubercle
- Tibial tubercle: Distal extent of incision
- Medial femoral condyle: Palpable medially
- Medial joint line: At level of inferior patella
- VMO muscle belly: Visible superomedially
Incision Planning:
| Landmark | Position |
|---|---|
| Proximal extent | 5-10 cm above patella (TKA) |
| Central portion | Medial to patella |
| Distal extent | Tibial tubercle or beyond |
| Orientation | Midline or slightly medial |
Classification
Anteromedial Approach Variations
| Variation | Description | Best Indication |
|---|---|---|
| Medial Parapatellar | Standard TKA arthrotomy through/near VMO | Primary and revision TKA |
| Subvastus | Under VMO, muscle sparing | TKA in selected patients |
| Midvastus | Split VMO, compromise approach | TKA with limited exposure |
| Mini-incision | Limited exposure for minimally invasive | UKA, selected TKA |
| Anteromedial portal | Arthroscopic portal at joint line | Arthroscopy, ACL |
| Extended anteromedial | Distal extension along tibia | Plateau fractures, MCL |
Selection Criteria:
- Patient factors: obesity, ROM, deformity
- Procedure type: TKA vs UKA vs trauma
- Surgeon experience and preference
- Previous incisions on medial knee
Clinical Assessment
Preoperative History
Preoperative History
Key History Elements:
- Previous knee surgery or incisions
- Skin quality and soft tissue condition
- History of DVT/PE or anticoagulation
- Corticosteroid or immunosuppressant use
- Diabetes and healing concerns
Factors Affecting Approach Choice:
| Factor | Preferred Approach |
|---|---|
| Primary TKA, standard patient | Medial parapatellar |
| Young patient, concern for recovery | Consider subvastus |
| Obese patient | Medial parapatellar |
| Previous medial incision | Use existing incision |
| Stiff knee, limited ROM | Medial parapatellar |
| Valgus deformity | Lateral approach consideration |
Physical Examination
Physical Examination
Key Examination Findings:
- Skin: Scars, trophic changes, vascularity
- Soft tissue: Swelling, effusion, skin mobility
- Range of motion: Flexion, extension contracture
- Alignment: Varus/valgus deformity
- Patellar tracking: Lateral tilt, subluxation
Specific Assessments:
- Previous incision location and quality
- VMO bulk and function
- Quadriceps strength
- Patellar mobility and J-sign
- Vascular status (pulses, capillary refill)
Approach Selection
Surgical Planning
Approach Selection Algorithm:
| Scenario | Recommended Approach |
|---|---|
| Standard primary TKA | Medial parapatellar |
| Revision TKA | Medial parapatellar (may need tibial tubercle osteotomy) |
| UKA (medial) | Mini-medial parapatellar |
| Medial plateau fracture | Extended anteromedial |
| MCL reconstruction | Anteromedial with distal extension |
| ACL reconstruction | Anteromedial portal or small incision |
Patient Positioning:
- Supine with knee flexed 90° over table edge
- Foot of bed dropped or leg holder
- Tourniquet applied to upper thigh (if used)
- Ensure full flexion and extension achievable
Investigations
Imaging Studies
Standard Preoperative Imaging:
| Study | Purpose |
|---|---|
| Weight-bearing AP radiograph | Assess alignment, joint space |
| Lateral radiograph | Tibial slope, patella alta/baja |
| Skyline/Merchant view | Patellofemoral joint, tracking |
| Long leg alignment | Mechanical axis for TKA planning |
Additional Imaging (Selected Cases):
- MRI: Soft tissue pathology, MCL injury, meniscal disease
- CT: Complex deformity, bone loss, previous hardware
- Vascular studies: If peripheral vascular disease suspected
Management
📊 Management Algorithm
Click to expand
Surgical Setup
Patient Positioning:
- Supine on standard operating table
- Knee flexed 90° over edge of bed
- Leg holder or foot of bed dropped
- Ensure hip and ankle freely mobile
Equipment:
| Item | Purpose |
|---|---|
| Tourniquet | Bloodless field (thigh, 250-300 mmHg) |
| Leg holder | Maintain flexion, free movement |
| Bump under hip | Neutral rotation |
| Bovie cautery | Hemostasis |
| Retractors | Hohmann, bent Hohmann for exposure |
Surgical Technique
Incision: Midline skin incision or slightly medial (anterior midline for TKA). From 5cm above patella to tibial tuberosity.
Arthrotomy: Incise joint capsule along medial patellar border:
- Start proximally in quadriceps tendon (may split vastus medialis obliquus near its insertion)
- Continue along medial patella
- Then medial to patellar tendon
Patella Eversion: After releasing soft tissue attachments, evert patella laterally. May need lateral retinacular release if difficult to evert.
Exposure: Provides excellent exposure of entire joint (femur, tibia, patella) for TKA.
Structures at Risk
Critical Structures
Saphenous Nerve: Accompanies great saphenous vein. At risk with distal extension. Injury causes numbness over medial knee and leg.
Infrapatellar Branch of Saphenous Nerve: Small branch running anterior to MCL. Often transected in TKA. Causes small area of lateral patellar numbness (usually well-tolerated).
Patellar Tendon: Can be damaged during eversion if technique poor. Risk of avulsion.
Complications
Early Complications
| Complication | Incidence | Prevention |
|---|---|---|
| Wound dehiscence | 1-2% | Careful closure, no tension |
| Haematoma | 2-3% | Meticulous hemostasis, consider drain |
| Superficial infection | 1-2% | Prophylactic antibiotics, aseptic technique |
| DVT | 1-2% (with prophylaxis) | VTE prophylaxis protocol |
| Patellar tendon injury | Rare | Careful technique, protect tendon |
Management Principles:
- Early recognition and intervention
- Wound issues: early wound care, may need debridement
- Haematoma: aspiration if tense, rule out bleeding disorder
- Infection: antibiotics, may need washout
Postoperative Care
Immediate Postoperative Care
Day 0-1:
- Compression dressing
- Ice therapy
- Elevation above heart level
- DVT prophylaxis (LMWH or other per protocol)
- Analgesia (multimodal approach)
Wound Management:
| Timeframe | Action |
|---|---|
| Day 1-2 | Check dressing, ensure no excessive bleeding |
| Day 2-3 | Remove drain if present |
| Day 10-14 | Suture/staple removal |
| Week 2-6 | Scar massage when healed |
VTE Prophylaxis:
- Mechanical: TED stockings, foot pumps
- Chemical: LMWH or aspirin per protocol
- Duration: 2-6 weeks depending on risk
Outcomes
Functional Outcomes
TKA Outcomes (Any Approach):
| Metric | Result |
|---|---|
| Pain relief | 90-95% significant improvement |
| ROM | Average 115° flexion |
| Patient satisfaction | 85-90% |
| Return to function | 3-6 months typical |
| Sports (low-impact) | 6-12 months |
Factors Affecting Outcome:
- Preoperative function and ROM
- Patient expectations and motivation
- Surgical technique and alignment
- Implant design and fixation
- Rehabilitation compliance
Evidence Base
Key Studies
Approach Comparison RCTs:
| Study | Comparison | Finding |
|---|---|---|
| Berstock 2018 (Cochrane) | MPP vs Subvastus | No clinically important difference |
| Xie 2012 (Meta) | MPP vs Subvastus | Early benefits subvastus, no long-term difference |
| Liu 2014 (Meta) | MPP vs Midvastus | Similar outcomes |
| Pongcharoen 2013 | MPP vs Subvastus | Faster early recovery subvastus |
Evidence Level:
- Multiple RCTs and meta-analyses available
- Level I evidence: No significant long-term difference between approaches
- Surgeon experience and patient selection more important
Infrapatellar Nerve:
- Mistry 2016: Nerve transection in 100% TKA
- Sensory deficit well-tolerated in most patients
- Does not correlate with functional outcomes
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
VIVA SCENARIOStandard
Scenario 1: Anteromedial Knee Approach
EXAMINER
"Describe the medial parapatellar approach to the knee for total knee arthroplasty."
EXCEPTIONAL ANSWER
The medial parapatellar approach is the standard approach for total knee arthroplasty. The patient is positioned supine with the knee flexed. I make a midline or slightly medial skin incision extending from approximately 5cm above the patella to the level of the tibial tuberosity. For the arthrotomy, I incise the capsule starting in the quadriceps tendon, then continue along the medial border of the patella and finally medial to the patellar tendon. This may involve splitting the vastus medialis obliquus near its insertion on the patella. I then evert the patella laterally to expose the joint. If the patella is difficult to evert, I may need to perform a lateral retinacular release. This provides excellent exposure of the femur, tibia, and patella for TKA. Structures at risk include the infrapatellar branch of the saphenous nerve which crosses anterior to the MCL and is often transected, causing a small area of numbness lateral to the incision. If I extend the approach distally along the medial tibia, I must protect the saphenous nerve and vein which run together posteriorly. The pes anserinus (sartorius, gracilis, semitendinosus) is a landmark distally. At closure, I repair the capsule and quadriceps tendon carefully to restore the extensor mechanism.
KEY POINTS TO SCORE
Midline or medial skin incision
Arthrotomy: Quad tendon → medial patella → medial to patellar tendon
Evert patella laterally for exposure
Saphenous nerve at risk distally
COMMON TRAPS
✗Not knowing arthrotomy details
✗Forgetting lateral retinacular release option
✗Not knowing pes anserinus order
LIKELY FOLLOW-UPS
"What is the subvastus approach?"
"What nerve is usually transected in TKA?"
VIVA SCENARIOChallenging
Scenario 2: Inadequate Exposure During Subvastus TKA - Intraoperative Decision-Making
EXAMINER
"You are performing a total knee arthroplasty via the subvastus approach in a 62-year-old man with primary osteoarthritis. You chose this approach because the patient is relatively young, active, and has good preoperative range of motion (0-125°). You have made your incision, dissected under the vastus medialis obliquus (VMO), and entered the joint. However, after attempting to evert the patella, you find the exposure is significantly limited. The patella will only partially evert and you cannot adequately visualize the anterior femur or safely position your cutting guides. You attempt a lateral retinacular release but the patella still does not fully evert. You are now struggling to proceed with the femoral preparation. The patient is obese (BMI 34) and the soft tissues are bulky making the limited exposure even more challenging. Your assistant suggests converting to a standard medial parapatellar approach. How do you proceed?"
EXCEPTIONAL ANSWER
I would convert to a standard medial parapatellar approach to obtain adequate exposure. The subvastus approach, while theoretically muscle-sparing, has clear limitations when exposure is inadequate - attempting to proceed with poor visualization compromises patient safety through risks of malposition, soft tissue damage, and technical errors. Conversion is a recognized intraoperative decision, not a complication, occurring in 5-15% of attempted subvastus approaches particularly in obese patients or those with limited ROM. To convert, I would extend my arthrotomy proximally into the quadriceps tendon and through the VMO insertion on the patella, effectively creating a medial parapatellar arthrotomy. This involves incising through the VMO tendon where it inserts onto the superomedial patella, then continuing along the medial patellar border as I have already done. The key is to make this decision early before struggling for prolonged periods - better exposure leads to better outcomes and patient safety is paramount. The theoretical benefits of VMO preservation are negated if I cannot perform the arthroplasty safely and accurately. Once converted, I proceed with standard medial parapatellar technique: adequate proximal soft tissue release, careful patella eversion (lateral release already performed), and then standard TKA steps. At closure, I ensure meticulous repair of the quadriceps mechanism and VMO to optimize patellar tracking. I would counsel the patient post-operatively that the approach was modified intraoperatively to ensure the best possible outcome - studies show no difference in long-term outcomes between planned MPP and converted subvastus approaches.
KEY POINTS TO SCORE
Subvastus exposure limitations - higher conversion rate (5-15%) particularly in obese patients or limited ROM: Not a true internervous plane, lifts VMO off septum, provides limited proximal exposure; Obesity (BMI greater than 30), bulky soft tissues, stiff knees (ROM less than 90°) predict inadequate exposure; Attempting to proceed with poor visualization compromises safety
Conversion to medial parapatellar not a complication - recognized intraoperative decision: Better to convert early than struggle with inadequate exposure, patient safety paramount over theoretical muscle-sparing benefits; Conversion involves extending arthrotomy proximally through VMO insertion and into quad tendon, creating standard MPP arthrotomy; Studies show no difference long-term outcomes between planned MPP and converted subvastus
Inadequate exposure risks during TKA - cannot compromise on visualization: Femoral component malposition (flexion-extension, rotation errors), tibial component malposition (slope, alignment errors), soft tissue damage (patellar tendon avulsion, VMO damage), ligament balancing errors; Accurate component position requires excellent exposure - poor exposure leads to poor outcomes regardless of approach
Technical execution of conversion - extend arthrotomy proximally: Incise through VMO insertion on superomedial patella, continue into quadriceps tendon proximally (standard MPP incision path), VMO already mobilized from subvastus dissection; Perform adequate proximal soft tissue releases for patella eversion, lateral retinacular release already performed; Proceed with standard TKA technique ensuring accurate alignment and soft tissue balance
Patient counseling and outcomes - no long-term detriment from conversion: Meta-analyses (Berstock 2018 Cochrane, Xie 2012) show no clinically important difference MPP vs subvastus at 1 year or beyond, theoretical early recovery benefits subvastus not realized if conversion required; Conversion rate higher in obese (BMI greater than 30), stiff knees (ROM less than 90°), valgus deformity; Post-operative counseling: Approach modified to ensure best outcome, no expected functional difference, standard TKA rehabilitation
COMMON TRAPS
✗Persisting with inadequate subvastus exposure despite poor visualization - high risk of component malposition, soft tissue damage, technical errors; Patient safety must override theoretical approach benefits; Better outcomes with good MPP exposure than struggling with inadequate subvastus
✗Not recognizing obesity (BMI 34) as contraindication to subvastus approach - predictive factor for inadequate exposure and conversion; Subvastus best suited for young, thin patients with good ROM; Should have planned MPP approach preoperatively given BMI and patient size
✗Viewing conversion as 'failure' or complication - conversion is recognized intraoperative decision based on exposure assessment; 5-15% conversion rate expected and acceptable; Surgeons should have low threshold to convert if exposure inadequate; Not disclosing conversion to patient creates medicolegal risk
✗Not performing adequate proximal releases after conversion - incomplete conversion leads to persistent inadequate exposure; Must extend arthrotomy fully into quad tendon, perform proximal soft tissue releases; Cannot perform 'partial conversion' - commit fully to MPP technique
✗Inadequate closure of converted approach affecting patellar tracking - meticulous VMO/quad tendon repair essential despite being disrupted by conversion; Poor closure predisposes to lateral patellar maltracking, instability; Use strong suture (#1 Vicryl or Ethibond), test tracking with trial components before final closure
LIKELY FOLLOW-UPS
"What patient factors predict the need for conversion from subvastus to medial parapatellar?"
"What is the reported conversion rate for subvastus approach in the literature?"
"How would your preoperative planning differ for an obese patient versus a thin patient regarding approach selection?"
VIVA SCENARIOCritical
Scenario 3: Patellar Tendon Avulsion During TKA - Critical Complication Management
EXAMINER
"You are performing a primary total knee arthroplasty via the medial parapatellar approach in a 71-year-old woman with end-stage osteoarthritis. The patient has significant stiffness preoperatively with only 75° of knee flexion. You have made your standard skin incision and arthrotomy. When attempting to evert the patella to expose the joint, despite having performed a lateral retinacular release, you encounter significant resistance. You apply traction to evert the patella and suddenly feel a 'give' with loss of resistance. On inspection, you find that the patellar tendon has avulsed from the inferior pole of the patella, detaching a small fragment of bone. The patella is now freely mobile without connection to the tibial tubercle. There is no tension in the extensor mechanism. This is 20 minutes into the case and you have not yet made any bone cuts. How do you manage this intraoperative complication?"
EXCEPTIONAL ANSWER
This is a devastating extensor mechanism disruption requiring immediate repair before proceeding with the arthroplasty. Patellar tendon avulsion from the inferior pole is one of the most serious TKA complications with significant functional consequences if not properly addressed - reported in 0.17-1.0% of primary TKAs, higher risk in stiff knees, rheumatoid arthritis, and revision surgery. My immediate management: (1) I would inform my assistant and theatre team of the complication, request additional instruments (heavy non-absorbable suture, drill, suture anchors or wires), and mentally prepare for a significantly longer and more complex procedure; (2) I would carefully examine the avulsion pattern - the tendon has pulled off the inferior pole with a small bone fragment, so I have tendon-bone avulsion rather than mid-substance rupture (better for repair); (3) The key decision is whether to repair BEFORE or AFTER completing the arthroplasty. The gold standard approach is to repair the patellar tendon FIRST before proceeding with TKA - this protects the repair during arthroplasty bone cuts and trialing, allows me to maintain knee flexion during repair without prosthesis in situ, and prevents contamination of the repair with bone cement. My repair technique: (1) Prepare the inferior pole of the patella by creating drill holes - two parallel 2.5mm drill holes from inferior to superior pole, exiting through the anterior cortex superiorly; (2) Use heavy non-absorbable braided suture (Ethibond #5 or FiberWire #2) in Krackow locking configuration through the patellar tendon for 4-5cm of tendon purchase; (3) Pass both limbs of the suture through the patellar drill holes from inferior to superior, exiting anteriorly; (4) With the knee in full extension, tension the sutures to reduce the tendon back to the inferior pole (may need to reduce the small bone fragment first); (5) Tie the sutures over the anterior patella surface, potentially over a bone bridge or button to prevent cheese-wiring; (6) Consider supplementing with cerclage wiring (18-gauge) around the patella in a circumferential fashion, passing through the tendon distally to add mechanical support; (7) Augment with transosseous tunnel repair if the bone quality permits. After secure repair is achieved with the knee in extension, I test the repair by gently flexing the knee to 30-40° - the repair should hold without gapping. Then I proceed with the TKA: femoral cuts first (allowing distal femoral resection), then tibial cuts. I would limit knee flexion throughout the procedure to 60-90° maximum to protect the repair. After trialing and cementing components, I recheck the patellar tendon repair integrity. At closure, I perform meticulous repair of all layers. Post-operatively: immobilize in extension brace or cylinder cast for 6 weeks, no active knee extension, passive ROM only 0-30° for first 6 weeks, then gradual progression. Weight-bearing toe-touch only for 6 weeks, then progressive. Inform patient of complication, likely prolonged (6 month minimum) rehabilitation, risk of extensor lag (20-30%), risk of re-rupture (5-10%), potential need for further surgery (tendon allograft augmentation if repair fails). Document thoroughly in operation notes. This complication significantly worsens TKA outcomes - reported rates of extensor lag 20-40%, reoperation 15-25%, patient dissatisfaction high. Prevention is key: avoid forceful patella eversion in stiff knees, consider quadriceps snip or tibial tubercle osteotomy if resistance encountered, recognize high-risk patients (stiff knee less than 90° ROM, RA, revision, chronic steroid use).
KEY POINTS TO SCORE
Patellar tendon avulsion - devastating extensor mechanism disruption (0.17-1.0% primary TKA, higher in stiff knees): Occurs during forceful patella eversion when resistance encountered, higher risk if preoperative ROM less than 90°, RA, revision TKA, chronic steroids; Avulsion typically at inferior pole of patella (bone-tendon junction) rather than mid-substance; Complete loss of extensor mechanism continuity - patella no connection to tibial tubercle; Requires immediate recognition and repair before proceeding with arthroplasty
Repair BEFORE completing TKA - gold standard approach protecting repair during bone cuts: Repairing first prevents contamination with cement, allows easier manipulation without components, maintains normal anatomy during repair; Repair technique: (1) Two parallel 2.5mm drill holes inferior-to-superior through patella, (2) Heavy non-absorbable suture (Ethibond #5, FiberWire #2) in Krackow locking configuration through tendon (4-5cm purchase), (3) Pass sutures through patellar drill holes, tension with knee in extension, tie over anterior patella (bone bridge or button), (4) Consider supplemental cerclage wire (18-gauge) circumferentially around patella through tendon distally
Intraoperative decision-making and TKA completion: After secure repair with knee in extension, test by gently flexing to 30-40° without gapping; Proceed with TKA limiting flexion to 60-90° maximum throughout to protect repair; Femoral cuts first, then tibial cuts; Trial components carefully, recheck repair after cementing; Meticulous closure all layers
Post-operative protocol - prolonged protected rehabilitation (6 months minimum): Immobilization: extension brace or cylinder cast 6 weeks, Passive ROM only 0-30° first 6 weeks then gradual progression, NO active knee extension 6 weeks (avoid quadriceps activation stressing repair), Weight-bearing: toe-touch only 6 weeks then progressive; Expect prolonged rehabilitation, high risk extensor lag (20-40% cases), re-rupture risk 5-10%, may need further surgery if repair fails (allograft augmentation)
Prevention strategies in high-risk patients (stiff knee ROM less than 90°, RA, revision): NEVER forcefully evert patella if resistance encountered - high avulsion risk; Extensile exposure techniques if limited exposure: (1) Quadriceps snip (oblique incision in VMO/quad tendon), (2) Tibial tubercle osteotomy with bone fragment (allows controlled distal mobilization); Recognize high-risk patients preoperatively: stiff knee, RA, revision, chronic steroid use; Lower threshold for extensile techniques rather than risking avulsion; Patient counseling pre-op about extensor mechanism injury risk in stiff knees
COMMON TRAPS
✗Attempting to proceed with TKA without immediate repair of patellar tendon avulsion - will lead to permanent extensor mechanism dysfunction; Must recognize and repair immediately; Delaying repair until after TKA completion compromises repair integrity and increases contamination risk
✗Inadequate suture purchase in patellar tendon (less than 4cm) - insufficient mechanical strength, high failure rate; Must use Krackow locking configuration with minimum 4-5cm tendon purchase; Heavy non-absorbable suture essential (Ethibond #5 or FiberWire #2), absorbable suture contraindicated
✗Not protecting the repair during TKA completion - excessive knee flexion during bone cuts or trialing stresses repair; Limit flexion to 60-90° maximum during remainder of procedure; Some surgeons complete femoral cuts first to allow distal femoral resection reducing patellofemoral constraint
✗Inadequate post-operative protection - early active knee extension or aggressive ROM will rupture repair; Must immobilize in extension 6 weeks, passive ROM only initially, NO active extension 6 weeks; Weight-bearing restrictions critical (TTWB 6 weeks); Early aggressive physio is contraindicated and risks repair failure
✗Not informing patient of complication and expected outcomes - medicolegal risk and poor patient experience; Must document thoroughly, inform patient immediately post-op, set realistic expectations (prolonged rehab, high extensor lag risk, potential re-rupture); Patient dissatisfaction high if not counseled appropriately; Outcomes significantly worse than uncomplicated TKA
LIKELY FOLLOW-UPS
"What are the alternative extensile exposure techniques that could have prevented this complication?"
"What is a quadriceps snip and when would you consider it?"
"What are the reported outcomes of patellar tendon avulsion repairs during TKA?"
"If the repair fails at 3 months, what are your options for salvage?"
MCQ Practice Points
Exam Pearl
Q: What are the surgical indications for the anteromedial approach to the knee?
A: Primary indications: ACL reconstruction (hamstring or BTB graft harvest and femoral tunnel drilling); Medial meniscus repair; MCL repair/reconstruction; Medial tibial plateau fractures; Tibial eminence fractures; Loose body removal. Often combined with anterolateral approach for multiligament reconstruction. Provides direct access to medial compartment, posteromedial capsule, and medial meniscus.
Exam Pearl
Q: What are the key anatomical structures at risk during the anteromedial knee approach?
A: Infrapatellar branch of saphenous nerve: Crosses surgical field, causes painful numbness if injured (avoid by staying close to patella); Saphenous nerve and vein: At risk with distal extension along medial border; MCL superficial fibers: Divided in some approaches; Medial inferior genicular artery: Lies along medial joint line; Pes anserinus tendons (sartorius, gracilis, semitendinosus): Protect during distal extension.
Exam Pearl
Q: What is the interval used in the anteromedial knee approach?
A: The approach uses the interval between medial border of patellar tendon and VMO (vastus medialis obliquus). Incision extends from medial patella margin, along medial patellar tendon border, to tibial tubercle. For ACL surgery, extend distally to access hamstring tendons. The medial retinaculum and capsule are incised to enter the joint. Deep dissection may require release of the coronary ligament for meniscal access.
Exam Pearl
Q: How does the anteromedial approach differ from the medial parapatellar approach for TKA?
A: Anteromedial (mini): Smaller incision, stays lateral to VMO, limited exposure, used for arthroscopy portals, meniscal surgery, ACL. Medial parapatellar (standard TKA): Extends through VMO tendon, allows patellar eversion, provides full exposure of knee joint for arthroplasty. The medial parapatellar is more extensile but disrupts VMO insertion, potentially affecting quadriceps function and patellar tracking.
Exam Pearl
Q: What are the advantages and limitations of the anteromedial arthroscopy portal?
A: Advantages: Provides working access to medial compartment; Allows ACL graft passage; Good angle for tibial tunnel drilling; Meniscal suture placement. Limitations: Limited visualization compared to lateral portal; Risk to infrapatellar nerve branch; Instrument crowding with multiple portals. Portal placed just medial to patellar tendon, at joint line level, with knee flexed 90°. Transillumination helps avoid vessels.
Australian Context
Australian Epidemiology
TKA Statistics (AOANJRR 2023):
- Approximately 70,000 TKAs performed annually
- Median age: 69 years
- Female predominance: 56%
- Primary indication: Osteoarthritis (97%)
- Most common approach: medial parapatellar (exact numbers not tracked)
Registry Monitoring:
- AOANJRR tracks implant survival, not surgical approach
- Overall revision rate: 5.6% at 10 years
- Best performing implants identified annually
ANTEROMEDIAL KNEE APPROACH
High-Yield Exam Summary
Medial Parapatellar Arthrotomy
- •Quad tendon → medial patella → medial to PT
- •Through or near VMO insertion
- •Evert patella laterally
- •Lateral release if needed
Variations
- •Subvastus: Under VMO (muscle sparing)
- •Midvastus: Split VMO
Structures at Risk
- •Saphenous nerve/vein (distal extension)
- •Infrapatellar branch (often transected)
- •Patellar tendon (avoid avulsion)
Pes Anserinus (SGS)
- •Sartorius (superficial)
- •Gracilis (middle)
- •Semitendinosus (deep)