Insall et al. report the first 2-4 year clinical outcomes of the Posterior Stabilized (PS) condylar prosthesis, introduced in 1978 as a modification of the Total Condylar design. The PS implant replaces PCL function with a tibial polyethylene spine and transverse femoral cam. Results in 118 arthroplasties are compared against historical Total Condylar controls using identical HSS scoring methodology.
The Total Condylar prosthesis was already successful, but fewer than one-quarter of patients could climb stairs normally, and average ROM was only 90°. Those limitations drove Insall to redesign the implant around controlled femoral rollback.
This paper is why PS TKA became the default choice for knees with severe deformity, PCL deficiency, or cases where maximizing flexion and functional stair-climbing matters most. When you see a patient with a flexion contracture greater than 10-15° or significant coronal plane deformity requiring extensive ligament release, the PS design's cam provides a reliable stability backstop that the Total Condylar design cannot.
On the patella: the intercondylar box geometry and greater ROM both increase patellar loading. Use the smallest patellar button that provides adequate coverage, verify central tracking before closure (the patella should track without thumb pressure), and perform lateral release or proximal realignment proactively rather than reactively.
This paper directly launched the Insall-Burstein PS knee system and established the cam-spine mechanism as the defining feature of the PS design class still in use today.
The Posterior Stabilized Condylar Prosthesis: a Modification of the Total Condylar Design. Two to Four-Year Clinical Experience.
Radiological Assessment of Osteo-Arthrosis.
Mesenchymal Stem Cells.
Traumatic Arthritis of the Hip after Dislocation and Acetabular Fractures: Treatment by Mold Arthroplasty. an End-Result Study Using a New Method of Result Evaluation.
Bone: Formation by Autoinduction.
Treatment of Deep Cartilage Defects in the Knee with Autologous Chondrocyte Transplantation.
Interrater Reliability of a Modified Ashworth Scale of Muscle Spasticity
Osteoclast Differentiation Factor Is a Ligand for Osteoprotegerin/osteoclastogenesis-Inhibitory Factor and Is Identical to Trance/rankl.
Comparison of Upper Gastrointestinal Toxicity of Rofecoxib and Naproxen in Patients with Rheumatoid Arthritis. Vigor Study Group.
Magnetic Resonance Classification of Lumbar Intervertebral Disc Degeneration.
Novel Regulators of Bone Formation: Molecular Clones and Activities.
The Diagnosis of Osteoporosis.
"modes of Failure" of Cemented Stem-Type Femoral Components: a Radiographic Analysis of Loosening.
Biomechanical Measures of Neuromuscular Control and Valgus Loading of the Knee Predict Anterior Cruciate Ligament Injury Risk in Female Athletes: a Prospective Study.
Femoroacetabular Impingement: a Cause for Osteoarthritis of the Hip.
Prevention of Infection in the Treatment of One Thousand and Twenty-Five Open Fractures of Long Bones: Retrospective and Prospective Analyses.
The Variation in Isometric Tension with Sarcomere Length in Vertebrate Muscle Fibres.
Osteoarthritis: a Disease of the Joint as an Organ.
Radiological Demarcation of Cemented Sockets in Total Hip Replacement.
Ectopic Ossification Following Total Hip Replacement. Incidence and a Method of Classification.
The Operation of the Century: Total Hip Replacement.
Fatty Muscle Degeneration in Cuff Ruptures. Pre- and Postoperative Evaluation by CT Scan.
Osseointegrated Titanium Implants. Requirements for Ensuring a Long-Lasting, Direct Bone-To-Implant Anchorage in Man.
The Etiology of Chondromalacia Patellae.
Fracture and Dislocation Classification Compendium-2018.
The Three Column Spine and Its Significance in the Classification of Acute Thoracolumbar Spinal Injuries.
Dislocations after Total Hip-Replacement Arthroplasties.
Patient Satisfaction after Total Knee Arthroplasty: Who Is Satisfied and Who Is Not?
Problems in the Management of Type III (severe) Open Fractures: a New Classification of Type III Open Fractures.
The Value of Postural Reduction in the Initial Management of Closed Injuries of the Spine with Paraplegia and Tetraplegia. I.
Vacuum-Assisted Closure: a New Method for Wound Control and Treatment: Animal Studies and Basic Foundation.
A System for the Functional Evaluation of Reconstructive Procedures after Surgical Treatment of Tumors of the Musculoskeletal System.
A Controlled Trial of Arthroscopic Surgery for Osteoarthritis of the Knee
The Stabilizing System of the Spine. Part I. Function, Dysfunction, Adaptation, and Enhancement.
The Outcome and Repair Integrity of Completely Arthroscopically Repaired Large and Massive Rotator Cuff Tears.
The Tension-Stress Effect on the Genesis and Growth of Tissues. Part I. the Influence of Stability of Fixation and Soft-Tissue Preservation.
A System for the Surgical Staging of Musculoskeletal Sarcoma.
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Zoledronic Acid and Clinical Fractures and Mortality after Hip Fracture.
Factors of Patellar Instability: an Anatomic Radiographic Study.
Displaced Proximal Humeral Fractures. I. Classification and Evaluation.
Hip Morphology Influences the Pattern of Damage to the Acetabular Cartilage: Femoroacetabular Impingement as a Cause of Early Osteoarthritis of the Hip.
Porosity of 3D Biomaterial Scaffolds and Osteogenesis.
A Report: the Definition and Classification of Cerebral Palsy April 2006.
Clinician's Guide to Prevention and Treatment of Osteoporosis.
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Radiation Exposure from CT Scans in Childhood and Subsequent Risk of Leukaemia and Brain Tumours: a Retrospective Cohort Study.
Epidemiology of Adult Fractures: a Review.
Centers for Disease Control and Prevention Guideline for the Prevention of Surgical Site Infection, 2017.
Osteoblastic Cells Regulate the Haematopoietic Stem Cell Niche.
A Joint Coordinate System for the Clinical Description of Three-Dimensional Motions: Application to the Knee.
Consensus Statement on Concussion in Sport-The 5th International Conference on Concussion in Sport Held in Berlin, October 2016.
Oarsi Guidelines for the Non-Surgical Management of Knee Osteoarthritis.
Estimating the Prevalence of Limb Loss in the United States: 2005 to 2050.
Metastasis to Bone: Causes, Consequences and Therapeutic Opportunities.
Role of Proinflammatory Cytokines in the Pathophysiology of Osteoarthritis.
The Basic Science of Articular Cartilage: Structure, Composition, and Function.
Osteoporosis: Now and the Future.
Clinical Features of Metastatic Bone Disease and Risk of Skeletal Morbidity.
Transfusion of Plasma, Platelets, and Red Blood Cells in a 1:1:1 vs. a 1:1:2 Ratio and Mortality in Patients with Severe Trauma: the Proppr Randomized Clinical Trial
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Diagnosis and Management of Prosthetic Joint Infection: Clinical Practice Guidelines by the Infectious Diseases Society of America.
The Amazing Osteocyte.
Osteosarcoma Incidence and Survival Rates from 1973 to 2004: Data from the Surveillance, Epidemiology, and End Results Program.
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The 2018 Definition of Periprosthetic Hip and Knee Infection: an Evidence-Based and Validated Criteria.
Bone Quality--The Material and Structural Basis of Bone Strength and Fragility.
Prevalence of Muscular Dystrophies: a Systematic Literature Review.
Mechanisms of Bone Metastasis.
The Compressive Behavior of Bone as a Two-Phase Porous Structure.
Metastatic Bone Disease: Clinical Features, Pathophysiology and Treatment Strategies.
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Insall et al. report the first 2-4 year clinical outcomes of the Posterior Stabilized (PS) condylar prosthesis, introduced in 1978 as a modification of the Total Condylar design. The PS implant replaces PCL function with a tibial polyethylene spine and transverse femoral cam. Results in 118 arthroplasties are compared against historical Total Condylar controls using identical HSS scoring methodology.
The Total Condylar prosthesis was already successful, but fewer than one-quarter of patients could climb stairs normally, and average ROM was only 90°. Those limitations drove Insall to redesign the implant around controlled femoral rollback.
This paper is why PS TKA became the default choice for knees with severe deformity, PCL deficiency, or cases where maximizing flexion and functional stair-climbing matters most. When you see a patient with a flexion contracture greater than 10-15° or significant coronal plane deformity requiring extensive ligament release, the PS design's cam provides a reliable stability backstop that the Total Condylar design cannot.
On the patella: the intercondylar box geometry and greater ROM both increase patellar loading. Use the smallest patellar button that provides adequate coverage, verify central tracking before closure (the patella should track without thumb pressure), and perform lateral release or proximal realignment proactively rather than reactively.
This paper directly launched the Insall-Burstein PS knee system and established the cam-spine mechanism as the defining feature of the PS design class still in use today.