Overview
Primary total knee arthroplasty aims to relieve arthritic pain and restore a stable, functional knee with appropriate component size, alignment, soft-tissue balance and patellar tracking. This guide summarizes a conventional mechanically aligned, measured-resection reconstruction through a medial parapatellar approach. Implant-specific cuts, slope and fixation must follow the chosen system (Campbell, Chapter 8).
Indications and Preoperative Assessment
Confirm severe symptomatic arthritis with radiographic findings that match the clinical picture after appropriate nonoperative treatment.
Evaluate hip, spine, vascular and neurologic sources of pain when symptoms are atypical.
Document motion, flexion contracture, coronal deformity, ligament stability, extensor function and previous incisions.
Review long-leg alignment and any femoral or tibial bowing, retained implants or previous osteotomy that may compromise conventional guides.
Optimize medical, nutritional, wound and infection risks. Active infection and major extensor dysfunction require a different plan.
Choose cruciate retention or substitution, fixation and the level of constraint according to the anatomy and ligament competence, with backup options available.
(Campbell, Chapter 8.)
Exposure
Use an anterior midline incision of adequate length. Incorporate a suitable prior incision and protect skin vascularity when several scars are present.
Keep the medial flap thick and perform the medial parapatellar arthrotomy, retaining a cuff of quadriceps tendon for closure.
Extend the arthrotomy around the medial patellar border and along the medial side of the tendon onto the proximal tibia.
Mobilize the extensor mechanism carefully. Evert or laterally subluxate the patella as exposure permits.
Remove the ACL, accessible meniscal tissue and obstructing osteophytes; manage the PCL according to the selected implant.
Protect the patellar tendon insertion during tibial subluxation, flexion and retraction. Inadequate exposure should be corrected before traction avulses the tendon.
(Campbell, Chapter 8, Technique 8.1.)
Alignment and Bone Resection
Distal Femur
Review the relationship between femoral anatomic and mechanical axes before choosing the distal-cut angle.
Position the intramedullary guide according to the planned axis, accounting for bowing or canal distortion. Use an alternative alignment method when the canal is unsuitable.
Resect an amount matching the implant and reconstruction plan, rather than using extra distal resection as the first response to every flexion contracture.
Protect the joint line; excessive elevation can create midflexion instability.
(Campbell, Chapter 8, Technique 8.2.)
Femoral Rotation and Sizing
Cross-check the transepicondylar axis, AP axis and posterior condyles, considering any condylar hypoplasia or wear.
Do not rely on the posterior condyles alone in a valgus knee with lateral condylar hypoplasia.
Understand whether the system uses anterior or posterior referencing before changing size or modifying the flexion gap.
Complete the anterior, posterior and chamfer cuts while avoiding anterior notching or excessive posterior resection.
Make any box preparation required for a posterior-stabilized design according to its instrumentation.
(Campbell, Chapter 8, Technique 8.2.)
Proximal Tibia
Align the tibial resection with the planned mechanical axis and verify the ankle reference and any tibial bowing.
Set the posterior slope for the chosen implant and PCL strategy. Some systems incorporate slope in the insert, so a universal saw-cut slope is inappropriate.
Set resection depth against the correct reference plateau, accounting for cartilage and bone loss.
Protect the collateral ligaments, patellar tendon and posterior structures during cutting.
Assess the completed surface for alignment, support and defects before trial placement.
(Campbell, Chapter 8.)
Gap Balancing
Remove peripheral and posterior osteophytes before releasing supporting ligaments. Assess both coronal symmetry and the relationship between flexion and extension gaps with spacers or a tensioner. Recheck after each adjustment rather than performing large empiric releases (Campbell, Chapter 8).
Finding | Principle in Campbell |
|---|---|
Extension tight relative to flexion | Check posterior osteophytes and capsular tension; consider the effect of distal femoral adjustment on the joint line. |
Flexion tight relative to extension | Review component size, posterior resection, PCL tension and the referencing system. |
Both gaps equally tight | Additional tibial resection affects flexion and extension together, if appropriate to the reconstruction. |
Both gaps equally lax | Consider insert thickness after confirming component position and ligament competence. |
Asymmetric coronal gaps | Use targeted, incremental balancing; overrelease can create instability and increase constraint requirements. |
In a cruciate-retaining knee, excessive PCL tension can restrict flexion, while insufficient tension causes instability. If the PCL cannot be balanced or is incompetent, select a compatible substitution strategy rather than leaving a predictably unstable construct (Campbell, Chapter 8).
Patellar Assessment and Trial Reduction
Choose the resurfacing strategy based on the patient's patella, implant and operative plan.
If resurfacing, maintain appropriate residual bone and reproduce composite thickness without overstuffing.
With trial components in place, assess full extension, flexion, coronal stability and patellar tracking.
If tracking is abnormal, first reassess femoral and tibial rotation, component position and patellar reconstruction.
Use a lateral release only when the cause and need are established; preserve the superior lateral geniculate circulation where possible.
(Campbell, Chapter 8.)
Implantation and Closure
After satisfactory trials, remove components without hyperextending the unprotected knee.
Prepare the bone surfaces for the selected fixation. For cementation, lavage and dry the cut surfaces and follow the cement's working characteristics.
Seat the components while maintaining alignment and remove extruded cement, including material in posterior recesses.
Before inserting the final polyethylene, search carefully for cement and bone debris.
With final components, reassess motion, stability and tracking. Obtain hemostasis and close the arthrotomy and wound with appropriate tension.
(Campbell, Chapter 8, Technique 8.11.)
Final Checks
Appropriate size, axial alignment and rotation of both components.
Balanced gaps without excessive laxity, persistent contracture or unintended recurvatum.
Stable extensor mechanism and congruent patellar tracking.
Secure component seating, no loose cement and an appropriate final insert.
Intact tendon and ligament attachments, adequate hemostasis and acceptable soft-tissue closure.
(Campbell, Chapter 8.)
Postoperative Care
Begin mobilization with trained assistance when recovery allows. Loading follows the fixation and actual reconstruction. Rehabilitation emphasizes extension, progressive flexion, quadriceps strength, safe gait and daily activities. The authors no longer routinely use continuous passive motion except selected severe preoperative arthrofibrosis cases (Campbell, Chapter 8).
Discharge requires safe assisted walking and appropriate pain control and medical recovery. The source describes outpatient therapy commonly once or twice weekly over 6–8 weeks, supplemented by a home program. Progression must reflect the patient's strength, balance, wound and associated reconstruction.
Complications and Pitfalls
Malrotation and patellar maltracking, with pain or instability.
Unbalanced flexion or extension spaces, overrelease and midflexion instability.
Patellar tendon avulsion, fracture or excessive patellar resection.
Stiffness, infection, wound problems, venous thromboembolism and neurovascular injury.
Aseptic loosening, wear and persistent pain despite a technically intact reconstruction.
(Campbell, Chapter 8.)
References
Ford MC, Holland CT, Mihalko WM. Arthroplasty of the knee. In: Azar FM, Sawyer JR, Throckmorton TW, eds. Campbell's Operative Orthopaedics. 15th ed. Elsevier; 2026. Chapter 8, indications, pp. 417–418; primary approach and measured resection, pp. 428–434, Techniques 8.1–8.2; balancing and patellar tracking, pp. 435–444; implantation, pp. 444–446, Technique 8.11; postoperative management, pp. 447–448.