Patellofemoral Instability

Complex Primary Knee Replacement: Advanced Solutions for Challenging Knees

A complex primary knee replacement is a first-time knee replacement performed on a knee with significant challenges, such as severe deformity, bone loss, or inflammatory arthritis. These cases are managed effectively by a fellowship-trained knee subspecialist using advanced surgical techniques.

Subspecialist Training

Dr Richard J Allom (FRCS, FRACS) specialises exclusively in challenging knee surgeries, including complex primary arthroplasty.

Precision Technology

Utilises robotic assistance and personalised alignment techniques to correct complex deformities and precisely position implants.

Bone Reconstruction

Employs advanced techniques like metal augments and structural cones to rebuild significant bone loss, providing a stable foundation for the replacement.

Defining Complex Primary Arthroplasty

A complex primary knee replacement is a first-time knee replacement that faces significant challenges beyond simple wear-and-tear. These conditions require meticulous planning and advanced surgical techniques to achieve a successful outcome.

Not all knee replacements are straightforward. Some patients present with severe deformity, significant bone loss, previous fractures, or inflammatory arthritis. These challenges require subspecialist precision.

If you have been told your knee arthritis is "too complex", "too severe", or that you need a specialist with advanced training, you are in the right place. Complex primary knee replacement is Dr Richard Allom's subspecialist focus.

With dual fellowship training (FRCS, FRACS), extensive experience managing challenging cases, and access to advanced implant systems, Dr Allom provides expert care for complex cases. Complex does not mean impossible. It simply means you need the right surgeon with the right expertise.

Dr Allom serves patients across South West Sydney (Gledswood Hills, Campbelltown, Liverpool) and the Mid North Coast (Taree, Forster).

Conditions Requiring Complex Surgery

A standard knee replacement typically addresses moderate arthritis with good bone quality. In contrast, a complex case involves significant complications:

Severe Deformity

More than 15–20 degrees 'bow-legged' (varus) or 'knock-kneed' (valgus) alignment. This requires specialist techniques to rebalance the ligaments and reconstruct the joint properly.

Significant Bone Loss

Severe arthritis or old injuries can wear away the bone, leaving an inadequate foundation for a standard implant. This requires bone grafting or metal augments

Previous Fractures or Deformity

Fractures that have healed in a poor position (malunion) or retained hardware alter the joint’s alignment and require complex, pre-operative planning.

Severe Stiffness

A fixed flexion contracture (inability to fully straighten the knee) requires extensive release of scarred tissue during surgery to restore a functional range of motion.

Inflammatory Arthritis

Conditions like Rheumatoid Arthritis cause severe bone erosion and damage ligaments. This often necessitates more complex implants and close coordination with your rheumatologist.

History of Previous Knee Surgery

Converting an existing procedure, such as an osteotomy or a partial knee replacement, into a total knee replacement is a recognised complex scenario.

Subspecialist Management

The Technical Approach

A complex case requires a subspecialist's unique set of skills and tools. Dr Allom’s approach focuses on three core pillars to correct anatomy and ensure long-term stability:

Rebalancing the Knee

A severely deformed knee has ligaments stretched on one side and tight on the other. Dr Allom performs meticulous, measured releases to restore stability and select the correct implant to support this new balance. This prevents an unstable knee.

Rebuilding the Foundation (Bone Loss)

When bone is missing, a standard implant has no solid base. Dr Allom uses advanced solutions like metal augments (wedges or blocks) or porous metal cones (trabecular metal). These act as building blocks to reconstruct the missing bone, providing a durable platform for the new joint.

Precision Correction

Correcting severe deformity can put nearby nerves and blood vessels at risk. Dr Allom’s subspecialist training involves techniques to protect critical structures. He uses CT scans and robotic/navigation systems to execute the personalised plan with the highest precision.

Why Choose Dr Richard Allom for Your Complex Knee

Choose an expert whose daily practice involves the complex cases that others refer out.

Fellowship-Trained Knee Subspecialist

Dr Allom holds dual UK and Australian qualifications: FRCS (Eng) and FRACS (Orth). This level of advanced training is critical for managing non-standard cases.

Comprehensive Complex Case Experience

He regularly manages severe deformity, significant bone loss, post-traumatic arthritis, and failed previous surgeries. This is his focused expertise.

Technology-Enhanced Precision

Uses robotic and computer navigation systems to enhance precision, which is essential for correcting complex alignment and protecting soft tissues.

Access to Advanced Implant Systems

Has experience with the full spectrum of implant systems, including revision-specific implants, constrained systems, and rotating-hinge implants. This ensures the right solution for your unique anatomy.

Evidence-Based and Transparent

Treatment decisions are grounded in medical evidence. He provides transparent communication, setting realistic expectations and discussing all challenges honestly.

Accessible Regional Locations

Provides this subspecialist expertise at convenient locations across South West Sydney and the Mid North Coast, eliminating unnecessary travel.

The Complex Patient Journey and Outcomes

Complex cases require meticulous planning to ensure a safe procedure and optimal recovery. The surgery involves detailed steps designed to maximise your functional outcome.

Pre-Operative Planning

Your journey starts long before the operating theatre. Complex cases demand meticulous planning:

Comprehensive Assessment

Includes advanced imaging such as long-leg alignment X-rays and CT scans. This allows Dr Allom to create a precise digital plan for your surgery.

Medical Optimisation

Involves working with your GP to manage conditions like diabetes, advising on smoking cessation, and coordinating with your rheumatologist. This preparation is key to a safer surgery and smoother recovery.

The Surgical Process

The complexity means the surgery usually takes 2 to 3 hours, which is longer than a standard 60–90 minute procedure.

In the operating theatre, Dr Allom uses navigation or robotic assistance for precise bone cuts. He carefully releases tight soft tissues and reconstructs any bone defects with augments. He then rigorously tests the knee’s stability before selecting the final, most appropriate implant.

Because the surgery is more extensive, your hospital stay will likely be 3 to 6 days.

Recovery and Rehabilitation

Recovery from complex knee replacement requires commitment and patience. It is often longer than a standard procedure.

Recovery Phase	Typical Duration	Focus	Outcome
Early Healing	Weeks 1–6	Strict non-weight-bearing. Gentle mobilisation, pain management, soft tissue healing.	Safe discharge, initial range of motion (ROM) restoration.
Functional Recovery	Months 2–3	Gradual weight-bearing introduction, outpatient physiotherapy (strength, ROM).	Full weight-bearing, independent mobility without aids, return to light work.
Long-Term Outcomes	Months 3–12	Advanced strengthening, endurance, functional activities. Swelling resolution.	85–90% pain relief, functional ROM (typically 0–110 degrees), return to activities.

Outcomes and Realistic Expectations

It is important to have realistic expectations. The outcomes for complex cases are excellent, but the recovery path is different from standard procedures:

Functional Goal

The main goal is significant pain relief and restoring functional motion (typically 0–110 degrees of flexion). While a standard case might achieve 125 degrees, achieving 110 degrees in a complex, stiff knee is a major success.

Implant Longevity

Research shows implant survival is typically 90–94% at 10 years.

Risk Mitigation

Subspecialist expertise is focused on meticulous planning and technique to actively minimise the slightly higher risks associated with these complex procedures. Patient satisfaction is very high when expectations are clear from the start.

Activity Modification

Weight management reduces knee stress, assistive devices support mobility during flare-ups, and pacing activities avoids overexertion.

Frequently Asked Questions

Patellar dislocations usually happen due to a combination of factors. These include underlying anatomical risk factors (like a shallow groove for the kneecap, a high-riding kneecap, or alignment issues) and a specific event (like a sudden twist, pivot, direct blow, or landing awkwardly). Most people who experience recurrent dislocations have an underlying anatomical reason that makes their kneecap prone to instability after the first injury.

It depends on your individual risk factors. Non-surgical management (physiotherapy) might be suitable if it is your first dislocation, you do not have significant anatomical risk factors, you are older (over 25-30), or you have lower activity demands. However, surgery might be considered even after a first dislocation if you have major anatomical issues (like severe trochlear dysplasia, high patella alta, TT-TG >20mm), sustained a cartilage fracture, have a complete MPFL tear seen on MRI, are a young athlete in a high-risk sport, or have instability in both knees. Dr Allom will assess your specific situation and discuss personalised recommendations.

Overall success rates are good. Around 85-95% of patients achieve a stable kneecap after surgery. The risk of re-dislocation drops significantly to 5-15% (compared to 50-70% without surgery for recurrent instability). Patient satisfaction is high (80-95%), and about 70-90% return to their pre-injury activity levels. Success depends on choosing the right patients, addressing all anatomical issues, precise surgery, and commitment to rehabilitation.

Yes, re-dislocation is possible but uncommon (around 5-15% risk). It can happen due to a significant new injury, graft failure, underlying bony problems that were not addressed, technical issues during surgery (like graft placement or tensioning), or returning to sport too soon. To prevent this, it is crucial to address all anatomical factors, choose the right procedure, strictly follow the rehabilitation plan, progress return to sport gradually, and continue neuromuscular training.

The timeline varies depending on the demands of your sport. General guidelines are: low-impact sports (swimming, cycling) around 3-4 months; running sports 6-8 months; pivoting sports (netball, basketball, football) 9-12 months; high-risk activities (gymnastics, skiing) 12 months or more. However, return is based on meeting specific criteria, not just time: strength should be at least 90% of the other leg, full range of motion, passing functional tests, no apprehension, and clearance from Dr Allom. Returning too early significantly increases re-injury risk.

Each time the kneecap dislocates, it causes some damage to the cartilage lining the joint. This cumulative damage increases the long-term risk of developing arthritis. Untreated recurrent instability has a high arthritis risk (estimated 60-80% develop arthritis within 20 years). Surgical stabilisation significantly lowers the risk of further dislocations, helping to protect the joint, but it cannot completely eliminate the underlying arthritis risk resulting from previous damage. Having fewer dislocations before stabilisation surgery generally leads to better long-term joint health. Arthritis prevention involves early stabilisation if needed, addressing all anatomical risk factors, maintaining strong quadriceps, weight management, and appropriate activity modification.

Next Steps

If you have experienced patellar dislocation, especially if it keeps happening, an expert assessment is crucial. Dr Allom can determine if surgical stabilisation is the right option for you and which specific procedures will best address the underlying causes of your instability.

Dr Richard Allom provides comprehensive evaluation, advanced surgical techniques, and evidence-based rehabilitation to restore patellar stability and help you confidently return to your activities.

What to Bring: Please bring your referral letter, all relevant imaging studies (X-rays, CT scans, MRI if performed), and your list of current medications to your consultation.

Book Your Consultation

Convenient Locations in Two Regions

I consult and operate from five locations, providing local access to subspecialist expertise without the need for long-distance travel.

South West Sydney Locations

Phone Number

04 3818 3832

Gledswood Hills

The George Centre, Suite 12, 1A The Hermitage Way

Campbelltown

Centric Park, Level 3, 4 Hyde Parade

Liverpool

Sydney South West Private Hospital, Suite 3.02, 24-40 Bigge Street

Mid North Coast Locations

Phone Number

02 6551 0722

Taree

Mayo Private Hospital Specialist Suites, 2 Potoroo Drive

Forster

Dolphin Suites Consulting Rooms, 33 Breckenridge Street

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