1. Anterior Knee Pain Syndrome
James Barsi, MD
Assistant Professor of Orthopaedic Surgery
June 14, 2013

2. Anterior Knee Pain Syndrome
Pain with prolonged knee flexion or stairs
Vague, localized in peripatellar area

3. Background Diagnosis and treatment is challenging
“Anterior knee pain syndrome” groups together different but related pathologic entities

4. Anterior Knee Pain Syndrome
Activity Related
Patella tendonitis
ITB syndrome
Plica syndrome
Fat pad syndrome
Arthosis
Chondromalacia
Inflammatory arthritis
Constant Pain, not activity related:
Sympathetic dysfunction
Neuroma
Referred radicular pain
Secondary Gain
Anterior Knee Pain Syndrome
Sharp, intermittent pain:
Loose bodies
Unstable chondral damage
Patella Instability
Malalignment Syndromes

5. Pain
Free nerve endings are concentrated in the patella tendon, retinaculum, fat pad1
Patients with AKPS have perivascular proliferation of nociceptive axons in retinaclum2
Substance P nerve fibers are widespread within the soft tissues around the knee (retinaculum, synovium, fat pad). In patients with AKPS, more Substance P fibers were found in the fat pad and retinaculum3
(1) Biedert et al. Am J Sports Med 1992; 20: 430.
(2) Sanchis-Alfonso et al. Am J Sports Med 1998; 26;703
(3) Witonski et al. Knee Surg Sports Traumatol Arthrosc 1999; 7:

6. Clinical Evaluation
Not all anterior knee pain associated with patella alignment abnormalities
Radiographic findings not pathologic if patient not symptomatic

7. Physical Examination Observation Alignment Varus/Valgus Rotational
Patella tracking
Pes planus

8. Physical Exam Patella apprehension Tight lateral retinaculum
Quadriceps and hamstring tightness
Hip strength

9. Radiographs AP, lateral, Merchant axial view
Patella sitting centered in trochlea
Tilt
Trochlea morphology

10. 1. Witvrouw et al. Am J Sports Med 2000; 28: 480.
Predictors of Pain
282 adolescents
10% Patellofemoral Pain
Predictors of developing pain:
Decreased flexion of quadriceps, gastrocnemius
Increased VMO response time
Decreased explosive strength
Increased thumb to forearm mobility
1. Witvrouw et al. Am J Sports Med 2000; 28: 480.

11. 1. Zhang et al. Med Sci Sports Exer 2000; 32: 812.
Role of the Hip
Hip extensors absorb 25% energy during landing
Deficits in hip strength add to load on the knee.1
1. Zhang et al. Med Sci Sports Exer 2000; 32: 812.

12. Nonsurgical Management
Physical Therapy
Knee Brace
Orthotics

13. 1. Witbrouw et al. Am J Sports Med 2000; 28: 687.
Physical Therapy
Traditional concept of trying to achieve isolated VMO strength not supported by literature.
Closed vs open chain:
Both types produced improvements in strength, pain relief and return to function1
1. Witbrouw et al. Am J Sports Med 2000; 28: 687.

14. Does Physical Therapy Help?
84% of patients improved after 8 weeks of quadriceps & hip rehabilitation.
75% of patients maintain improvement 6 months to 7 years2
1. Doucette et al. Am J Sports Med 1992: 20: 434.
2. Kannus et al. JBJS 1999; 81:

15. Physical Therapy Attention should be paid to quadriceps flexibility
Strengthening done without causing pain
Emphasis on hip strengthening
Continued until plateau reached

16. Surgical Management Surgery is not necessary in most cases
Successful surgical treatment requires an accurate diagnosis (patella instability or patellofemoral malalignment)
Normal alignment and no instability may be symptomatic from tendinosis in the quadriceps or patella tendons, pathologic hypertrophy and inflammation in the medial plica
Damage to the articular surface may also cause pain

17. Chondroplasty
Arthroscopic debridement of grade 2 and 3 chondral lesions can be useful
58% good or excellent results with traumatic onset
41% good or excellent results with atraumatic onset1
1. Federico et al. Am J Sports Med 1997; 25:

18. Lateral release
Effective in treating a well-defined subset of patients
Mechanism
relieves pressure in lateral retinaculum
divides neuromatous nerves in the retinaculum
relieves pressure on the lateral facet of the patella

19. Lateral Release Ideal patient No instability Tight lateral retinaculum
Outcome related to chondral damage
59% satisfactory with >grade 31
92% good to excellent with < grade 22
1. Aderinto et al. Arthroscopy 2002; 18:
2. Shea et al. Arthroscopy 1992; 8:

20. Complications of Lateral Release
Persistent pain
Worsening instability
Suspect medial subluxation in any patient reporting persistent pain after lateral release
Test in decubitus with lateral knee up, patella sags medially from gravity
Patient unable to flex knee

21. Tibial tubercle transfer
Lateral patellar tilt and subluxation
Results correlated to location of patella chondral lesions
global and proximal lesions did less well
Biomechanical studies show that transfer while decreasing overall load, transfers it disproportionally to proximal patella

22. Cartilage Restoration
OATS and autologous chondrocyte implantation
Small numbers have been reported and reports are mixed
Less aggressive procedures (chondroplasty, microfracture or abrasion) may be equally effective

23. Patellofemoral Arthroplasty
Low demand patients
Care at the time of surgery to ensure extensor mechanism is aligned

24. Summary Important to establish accurate diagnosis
Non-surgical management remains the most predictable method of treatment

25. Thank You