What are the limitations of the patellar instability severity score?

While the patellar instability severity score is highly validated, it should not replace clinical judgment. OpiCalc provides the latest evidence-based limitations for the patellar instability severity score to ensure safe bedside use and optimal diagnostic accuracy.

How does the patellar instability severity score compare to other SportsMedicine scores?

The patellar instability severity score is a gold-standard diagnostic tool. OpiCalc provides side-by-side clinical guidance to help clinicians choose the most specific evidence-based tool for their patient's presentation.

Is the patellar instability severity score free to use?

Yes. OpiCalc provides the patellar instability severity score completely ad-free and optimized for mobile bedside use, ensuring you can calculate medical risk swiftly and without distraction.

EVIDENCE SYNTHESIS

Clinical Reference Hub

Curated insights • How it Works • Practical Pearls • Evidence Base

CLINICAL INSIGHT

When to Use

Evaluating the risk of recurrent patellar dislocation after a primary event.
Guiding the decision between conservative vs. surgical management.
Screening for anatomical risk factors in patients with patellofemoral instability.

Clinical Objective

PISS quantifies the "anatomical risk" based on age and specific musculoskeletal parameters, providing a predictive score for recurrent failure.

CLINICAL INSIGHT

How it Works

The 6 Weighted Items

Age < 16 years

Bilateral Instability

Trochlear Dysplasia (High Grade)

Patella Alta (Caton-Deschamps >1.2)

TT-TG Distance > 20mm

Patellar Tilt

Total Score Range

The total score ranges from 0 to 7.

CLINICAL INSIGHT

Practical Pearls

Risk Thresholds

Score ≤ 3

Score ≥ 4

Clinical Pearls

Age is the single most powerful predictor of recurrence.
Trochlear dysplasia is weighted double (2 points) due to its profound impact on patellar tracking.
TT-TG (Tibial Tuberosity - Trochlear Groove) distance should be measured via CT or axial MRI.

CLINICAL INSIGHT

Next Steps

Management Decisions

Score ≥ 4: Discuss early surgical intervention (MPFL Reconstruction) to prevent progressive joint damage.
Score ≤ 3: Focus on progressive strengthening of the VMO and hip abductors.
High TT-TG (>20mm): Consider Tibial Tubercle Osteotomy (TTO) in addition to soft tissue stabilization.

Related Tools

CLINICAL INSIGHT

Evidence Base

Primary Reference

Patellar Instability Severity Score (PISS): A validation study.

Balcarek P, et al.Am J Sports Med2014

View Source

Clinical Evidence and Methodology

Clinical Reference Hub

When to Use

When to Use

Clinical Objective

How it Works

The 6 Weighted Items

Total Score Range

Practical Pearls

Risk Thresholds

Clinical Pearls

Next Steps

Management Decisions

Related Tools

Evidence Base

Primary Reference

Patellar Instability Severity Score

0 / 7

Age < 16 Years

Bilateral Instability

Trochlear Dysplasia (High Grade)

Patella Alta (Caton-Deschamps >1.2)

TT-TG Distance > 20mm

Patellar Tilt

Clinical Evidence and Methodology

Clinical Reference Hub

When to Use

When to Use

Clinical Objective

How it Works

The 6 Weighted Items

Total Score Range

Practical Pearls

Risk Thresholds

Clinical Pearls

Next Steps

Management Decisions

Related Tools

Evidence Base

Primary Reference

Patellar Instability Severity Score

0 / 7

Age < 16 Years

Bilateral Instability

Trochlear Dysplasia (High Grade)

Patella Alta (Caton-Deschamps >1.2)

TT-TG Distance > 20mm

Patellar Tilt