Proximal fibular osteotomy has been proposed as a simple and inexpensive alternative to high-tibial osteotomy and unicondylar knee arthroplasty and may be useful for low-income populations that cannot afford expensive treatment methods. However, there is no consensus existing regarding the mechanism by which it acts nor the outcome of this procedure. This study was performed to analyze the available evidence on the benefits of proximal fibular osteotomy and to understand the possible mechanisms in play. There are various mechanisms that are proposed to individually or collectively contribute to the outcomes of this procedure, and include the theory of non-uniform settlement, the too-many cortices theory, slippage phenomenon, the concept of competition of muscles, dynamic fibular distalization theory and ground reaction vector readjustment theory. The mechanisms have been discussed and future directions in research have been proposed. The current literature, which mostly consists of case series, suggests the usefulness of the procedure in decreasing varus deformity as well as improving symptoms in medial osteoarthritis. However, large randomised controlled trials with long-term follow-up are required to establish the benefits of this procedure over other established treatment methods.

1. Proximal Fibular Osteotomy
for Knee Osteoarthritis
- What is the evidence?
Dr Saseendar, MS, DNB, Dip SICOT,
FISOC (USA), FASS (Sing), FAPKASS, FASS (Korea),
Consultant Shoulder and Knee Arthroscopy Surgeon,
CARE Sports Injury, Chennai and Apollo Hospitals

2. https://kneesurgrelatres.biomedcentral.com/articles/10.1186/s43019-019-0016-0
Saseendar S, Kambhampati SBS, Samundeeswari S. Proximal fibular osteotomy in the
treatment of medial osteoarthritis of the knee – A narrative review of literature. Knee Surg &
Relat Res 31, 16 (2019) doi:10.1186/s43019-019-0016-0.

3. Medial osteoarthritis of the knee
• Knee - commonest site of osteoarthritis (OA)
• Significant research & advances in treatment of medial OA
• Surgical options for treatment
• High Tibial Osteotomy
• UKA
• TKA

4. Conservative options
PRP injection Hyaluronate
injection

5. Surgical options

6. Another school of thought
• Proximal fibular osteotomy or upper partial fibulectomy
to reduce knee pain in medial OA

7. Our Systematic Review
https://kneesurgrelatres.biomedcentral.com/articles/10.1186/s43019-019-0016-0

8. Aim
• Attempted to review existing literature
• To assess origin, biomechanics, indications & outcomes of this
procedure

9. Methodology
• Keyword: ‘proximal fibular osteotomy’
• Pubmed – 223
• Medline – 8
• Embase – 10
• Scopus – 204
• Cochrane Library – 7

10. Methodology
• Articles in English
• Articles which combined PFO with other surgical procedures (eg. HTO,
UKA) were excluded
• Bibliography of the articles were also searched
• Total ten articles that assessed clinical or biomechanical effects of PFO in
medial OA
• Outcomes and mechanisms proposed were studied
• Systematic review could not be done (few long-term studies)

11. RESULTS
• Origin
• Mechanisms and Outcomes
• Prognostic factors for better outcomes
• Surgical procedure
• Complications
• Future scope

12. Biomechanics of the varus knee
• Femur
• Functional decrease in femoral neck-shaft valgus
• Lateral bowing of the femoral shaft
• Reduction in the condylar shaft angle
• Mechanical axis shifts medially
Matsumoto T, Hashimura M, Takayama K, Ishida K, Kawakami Y, Matsuzaki T, et al. A radiographic
analysis of alignment of the lower extremities--initiation and progression of varus-type knee
osteoarthritis. Osteoarthr Cartil 2015;23(2):217-23.

13. Biomechanics of the varus knee
• Tibia
• Tibial plateau compression leads to steeping of medial plateau in early OA
• Bowing of tibia occurs later
• Mechanical axis shifts medially
Matsumoto T, Hashimura M, Takayama K, Ishida K, Kawakami Y, Matsuzaki T, et al. A radiographic
analysis of alignment of the lower extremities--initiation and progression of varus-type knee
osteoarthritis. Osteoarthr Cartil 2015;23(2):217-23.

14. Biomechanics of the varus knee
• Load-bearing in proximal tibia happens primarily in trabeculae rather than the peripheral cortex
Hvid I. Mechanical strength of trabecular bone at the knee. Dan Med Bull 1988;35(4):345-65.
Aging
Trabecular
osteopenia
Trabecular
collapse
Steeping
of medial
plateau

15. Origin of Proximal Fibular Osteotomy
• Yazdi et al (2014)
• Survey of joint reaction forces in cadaver knees after fibulectomy (fibula cuff resection for nonunion tibia, fibular tumor
resection, fibula graft harvest)
• Found decrease in the medial compartment pressure and
• Increase in the lateral compartment pressure
• Suggested that performing fibulectomy along with tibial osteotomies can have protective effect
Yazdi H, Mallakzadeh M, Mohtajeb M, Farshidfar SS, Baghery A, Givehchian B. The effect of partial fibulectomy
on contact pressure of the knee: a cadaveric study. Eur J Orthop Surg Traumatol 2014;24(7):1285-89.

16. Origin of Proximal Fibular Osteotomy
• Yang et al (2015)
• Published results of retrospective series of PFO surgeries performed since 1996
• Third Hospital of Hebei Medical University, Hebei, China
• Zhang, the senior surgeon attributes the idea to one of his students from a rural
hospital in China
Yang ZY, Chen W, Li CX, Wang J, Shao DC, Hou ZY, et al. Medial Compartment Decompression by Fibular
Osteotomy to Treat Medial Compartment Knee Osteoarthritis: A Pilot Study. Orthopedics 2015;38(12):e1110-4.

17. Rationale behind PFO
1. Concept of nonuniform settlement
2. Too many cortices theory
3. Slippage phenomenon
4. Concept of competition of muscles
5. Dynamic fibular distalisation theory

18. Concept of nonuniform settlement
• Term used in Architecture

19. Concept of nonuniform settlement
• Bone density of fibula higher than medial tibial plateau
• Osteoporosis leads to settlement
• However, fibular support does not allow lateral tibial plateau to settle
• Resultant varus deformity
Dong T, Chen W, Zhang F, Yin B, Tian Y, Zhang Y. Radiographic measures of settlement
phenomenon in patients with medial compartment knee osteoarthritis. Clin Rheumatol
2016;35(6):1573-78.

20. A - Normal knee
medial tibial load-bearing capacity =
cumulative lateral load-bearing capacity (tibial+fibular)
B – osteoporotic knee
medial tibial load-bearing capacity <
cumulative lateral load-bearing capacity (tibial+fibular)

21. Settlement value
• Height difference between highest point of lateral
tibial condyle and the lowest point of medial tibial
condyle
Dong T, Chen W, Zhang F, Yin B, Tian Y, Zhang Y. Radiographic measures of
settlement phenomenon in patients with medial compartment knee
osteoarthritis. Clin Rheumatol 2016;35(6):1573-78.

22. Settlement value
• positively related to knee varus
• positively related to Kellgren Lawrence grading of OA of the knee

23. • PFO - support of fibula is removed
• Lateral side “settles” down – Uniform settlement
C – Post PFO knee
medial tibial load-bearing capacity =
lateral load-bearing capacity (tibial + fibular)
B – osteoporotic knee
medial tibial load-bearing capacity <
cumulative lateral load-bearing capacity (tibial + fibular)
• Correction of deformity
• Relief in symptoms

24. Too many cortices theory
• Medial condyle - supported by one cortex
• Lateral condyle - supported by one tibial
cortex and two fibular cortices
• Leads to differential loading when medial
side collapses in a varus deformed knee
with intact fibula

25. Slippage phenomenon
• In varus knee, femur slides to the medial side - coronal tibiofemoral
subluxation or slippage phenomenon
• Maintains a high Knee Adduction Moment (KAM)
• Progression of varus deformity and pain

26. Concept of competition of muscles
• Uniform settlement after PFO takes time
• Can explain slow improvement in symptoms
• What is the reason for early symptomatic relief?
• Immediate improvement in HKA angle after high fibular osteotomy
• A rectified non-uniform settlement wouldn't be expected to be
evident immediately after a fibula resection

27. Concept of competition of muscles
• Nie et al analysed the activity of muscles after high fibular osteotomy
• increased in the long head of biceps femoris
• decreased in the peroneus longus
Nie Y, Huang ZY, Xu B, Shen B, Kraus VB, Pei FX. Evidence and Mechanism by which Upper
Partial Fibulectomy Improves Knee Biomechanics and Decreases Knee Pain of Osteoarthritis. J
Orthop Res 2018

28. Concept of competition of muscles
• Competition of muscles between Biceps femoris & Peroneus after
high fibular osteotomy created a vectior in the direction of valgus

29. Dynamic fibular distalisation theory
• Qin et al - 67 PFOs
• Clinical improvement proportional
• to distalisation of fibula and
• inclination angle of the proximal tibiofibular joint
• Compressive forces from distal fibula not transmitted to proximal fibula
Qin D, Chen W, Wang J, Lv H, Ma W, Dong T, et al. Mechanism and influencing factors of proximal
fibular osteotomy for treatment of medial compartment knee osteoarthritis: A prospective study. J Int Med
Res 2018;46(8):3114-23.

30. Dynamic fibular distalisation theory
• Muscles attached to proximal fibula (soleus, peroneus longus) pulled
fibular head in the distal direction - tensile force transmitted to LFC
through LCL
• Greater the distal displacement of the fibular head, better the correction
of varus deformity & the more significant the improvement in symptoms
Qin D, Chen W, Wang J, Lv H, Ma W, Dong T, et al. Mechanism and influencing factors of proximal fibular
osteotomy for treatment of medial compartment knee osteoarthritis: A prospective study. J Int Med Res
2018;46(8):3114-23.

31. More outcomes
• Huang et al – Valgus of 5-7 degrees at three months after the operation
• Most studies –
• increased valgus of knee
• improvement in medial joint space Radiographs at one year
• Wang et al24 - 46 patients with PFO, follow up of 12 months
• Significant decrease in VAS
• Improvement of knee and function subscores of American Knee Society Score
• Increase in medial joint space
Huang W, Lin Z, Zeng X, Ma L, Chen L, Xia H, et al. Kinematic Characteristics of an Osteotomy of the Proximal Aspect
of the Fibula During Walking: A Case Report. JBJS Case Connect 2017;7(3):e43.

32. Prognostic factors for better outcome
• Liu et al - 84 patients (111 knees)
• Patients with near-normal HKA Angle
(PFO can only partially correct varus deformity of tibial plateau)
• Patients with higher settlement value
(higher the settlement value, higher effect of lateral fibula support)
Liu B, Chen W, Zhang Q, Yan X, Zhang F, Dong T, et al. Proximal fibular osteotomy to treat medial compartment knee
osteoarthritis: Preoperational factors for short-term prognosis. PLoS One 2018;13(5):e0197980.

33. • Pre and postoperative radiographs
• female 63 years old
Utomo DN, Mahyudin F, Wijaya AM, Widhiyanto L. Proximal fibula osteotomy as an alternative to TKA and HTO
in late-stage varus type of knee osteoarthritis. J Orthop 2018;15(3):858-61.

34. • Improvement in axial alignment
• 79-year-old woman
Wang X, Wei L, Lv Z, Zhao B, Duan Z, Wu W, et al.
Proximal fibular osteotomy: a new surgery for
pain relief and improvement of joint function in
patients with knee osteoarthritis.
J Int Med Res 2017;45(1):282-89.

35. • Improvement in the joint space ratio
Wang X, Wei L, Lv Z, Zhao B, Duan Z, Wu W, et al. Proximal fibular osteotomy: a new surgery for pain relief
and improvement of joint function in patients with knee osteoarthritis. J Int Med Res 2017;45(1):282-89.

36. Surgical Procedure
• Resect a segment of the fibula
• 6-10 cm from the fibular head
• Nie et al – b/w extensor digitorum longus & peroneus longus/ peroneus
brevis
• Yang, Liu – b/w peronei & soleus

37. Surgical Procedure
• Influenced by common peroneal nerve and its branches
• Lower half of fibula – best
• Why proximal fibula, why not distal fibula?
• Incision in proximal half
• should be posterior to the coronal plane
• avoids peroneal nerve and its branches (lie in front of the coronal plane)
Ogbemudia AO, Umebese PFA, Bafor A, Igbinovia E, Ogbemudia PE. The level of fibula osteotomy and
incidence of peroneal nerve palsy in proximal tibial osteotomy. J Surg Tech Case Rep 2010;2(1):17-19.

38. Complications
• Peroneal Nerve palsy
• Yang et al
• 1.8% common peroneal nerve(CPN)
• 1.8% superficial peroneal nerve palsy which recovered completely between 3 and
10 months
• 14.5% had weakness which returned to normal within 4 weeks
Yang Z-YY, Chen W, Li C-XX, Wang J, Shao D-CC, Hou Z-YY, et al. Medial Compartment Decompression by Fibular Osteotomy
to Treat Medial Compartment Knee Osteoarthritis: A Pilot Study. Orthopedics 2015;38(12):e1110-4.

39. Scope for future research
• Double blinded RCTs
• Male vs female patients?
• Post traumatic varus deformity with medial osteoarthritis?
• Maximum varus angle until which the procedure can be successful?
• Combination strategies with?
• Cell-based regeneration strategies?
• Arthroscopy?
• Longevity of survival before needing TKA/ HTO/ UKA?

40. Saseendar S, Kambhampati SBS, Samundeeswari S. Proximal fibular osteotomy in the
treatment of medial osteoarthritis of the knee – A narrative review of literature. Knee Surg &
Relat Res 31, 16 (2019) doi:10.1186/s43019-019-0016-0.

41. THANK YOU!
Dr Saseendar,
MS, DNB, Dip SICOT, FISOC (USA), FASS (Sing), FAPKASS, FASS (Korea),
Consultant Shoulder and Knee Arthroscopy Surgeon,
Member of SICOT Education and Research Committees,
Apollo Hospital, Muscat,
Sultanate of Oman