Features of the Proximal Femoral Nail Antirotation (PFNA) Asia

The Proximal Femoral Nail Antirotation (PFNA), with its helical blade concept, is a state-of-the-art treatment method for proximal femoral fractures, providing rotational and angular stability with one single element. The intramedullary nail acts as an internal splint that controls but does not prevent micromovements of the bone fragments. The PFNA provides relative stability, leading to indirect healing through callus formation.

To help cope with the differences described above, an Asian version of the existing Proximal Femoral Nail Antirotation (PFNA) was developed and introduced into the market. The PFNA Asia (also known as PFNA II) (Fig 1) has a better fit to the smaller trochanteric area and narrower intramedullary canal of the Asian population. It features a lateral flat surface which makes insertion easier and lowers the pressure on the lateral cortex. The bend has been reduced to 5° versus 6° compared to the PFNA. The proximal diameter has been reduced to 16.5 mm (versus 17.0 mm). Furthermore, the spiral blade diameter has been reduced to 10.3 mm.

The PFNA Asian size comes in four different distal diameters from 9–12 mm, each in three lengths (170, 200, and 240 mm*). The long PFNA Asian size (260–340 mm, with 20 mm increments) is available in two distal diameters of 9 and 10 mm. Additional lengths of 340–420 mm in 40 mm increments are available with a distal diameter of 10 mm. The blade is available in lengths of 75–120 mm in steps of 5 mm. Two versions of Caput Collum Diaphyseal (CCD) angles of 125° or 130° are available. The nail is made out of titanium aluminum niobium (TAN) and sterile packaged.

In addition, some selected instruments have also been specifically designed for the smaller stature of the population and to the needs of the Asian surgeons.

The PFNA Asian size is indicated for pertrochanteric fractures (Müller AO Classification 31-A1 and 31-A2), intertrochanteric fractures (31-A3), and high subtrochanteric fractures (32-A1). The long version is indicated for low and extended subtrochanteric fractures, ipsilateral trochanteric fractures, combination fractures in the proximal femur, and pathological fractures.

*The 240 mm nail comes in two different distal diameters 9 and 10 mm only.

Japanese Proximal Femoral Nail (Antirotation) Study - The AOs First Completely Bilingual Study

AO Clinical Investigation (AOCID) has, in cooperation with Japanese colleagues, initiated the first multicenter study in orthopedic trauma in Japan in 2008. Among Japanese patients aged 65 years and older with proximal femoral fractures, the proportion of those aged 90 years and older has increased over the last decades from 3% in 1983 to nearly 20% in 2004. One reason for this is the increasing number of patients with osteoporosis in the older population. Compared to other ethnic groups, Asian people have the lowest bone mass.

Study background

The idea for the study came from the Asian Trauma Working Group (ASWG) because Asian people have different geometric proportions of the femoral bone compared to European or American populations. For example, studies have shown that Asian women have shorter femoral necks, smaller femoral neck angles, and a more anterior bowing of the shaft than white Americans. The new PFNA Asia has specially adapted sizes and geometry to better suit the local population. It boasts a flat lateral side, higher bending point of the nail resulting in a straighter tip point, a smaller medial-lateral bending of 5, and adapted surgical instruments. Japanese doctors were the driving force behind the development of the PFNA Asia and are pivotal to this study. In addition to the principal clinical investigator, Dr Takeshi Sawaguchi, Drs Tadashi Tanaka, Yasuhiro Nanri, and Atsushi Sakurai are also central to the study's success.

Although original PFNA have been in clinical use since 2005 in Japan, no data on the rate of mismatch are available yet. Therefore, one of the study's goals is to determine whether potential mismatch exists between the new PFNA Asia and Japanese patients, and whether both Japanese patients and surgeons needs will be met.

Objectives of the study

The primary objective of this prospective multicenter case series is to assess any fracture fixation complication and revision rates during the clinical use of the proximal femoral nail antirotation Asia (PFNA Asia) for the treatment of unstable, closed trochanteric fractures, classified according to the Müller AO Classification type 31-A2 or 31-A3. Fracture fixation complications include any bone/fracture- or implant/surgery-related event.

In addition to the assessment of potential mismatches of femoral medullary cavity and the PFNA Asia at the femoral great trochanter (lateral to blade insertion point), the middle medial portion and distal end of the nail are investigated: soft tissue, wound or general complications, prognostic factors for the occurrence of complications (eg, bone mineral density, dementia), length of hospital stay, walking ability, capacity to return to pre-injury status, quality of life, mortality, anatomical restoration (clinically and radiographically), length of surgery (skin to skin time) and operative handling of the implant and the instrumentation.

The follow-up schedule applying to this study includes initial hospitalization, as well as follow-up visits at 6 weeks, 12 weeks, 6 months and 12 months (these are the defined time intervals). The final evaluation of radiographs and complications will be performed by a study review board at the end of the study.

First completely bilingual study

Every document in the study is written in both Japanese and English. For example, every question on each case report form is asked in Japanese and English. The aim of this is to ease the filling out of the case report forms for Japanese colleagues. Additionally, for the first time, the OpVerdi database has been completely created in both languages. This naturally created a lot of work for the AOs team of computer specialists due to the different characters used in both languages. The key to success for the planning phase of this study was the close collaboration between the principle clinical investigator (PCI) in Japan and the responsible AOCID study manager, despite a distance of more than 10,000 kilometers between them.

Study conduct

The clinical investigation was performed in 20 Japanese hospitals over a three year period. The study population was 176 patients aged 65 years and older with a radiologically-confirmed, unstable, closed trochanteric fracture, sustained seven days or less before primary fixation treatment with the PFNA Asia.

Preliminary results and conclusion

Patient functional outcomes and health-related quality of life were similar between the pre-injury and final follow-up evaluations, and surgeons were highly satisfied with the implant and its handling. There is also a large societal benefit to enabling patients of advanced age that have sustained an unstable trochanteric fracture to return to their preinjury residential status.

The preliminary results from this study highlight the importance of having implants designed for older Asian patients available to surgeons in the region.

Full text and further information

Sawaguchi T, Sakagoshi D, Shima Y, Ito T, Goldhahn S. Do design adaptations of a trochanteric nail make sense for Asian patients? Results of a multicenter study of the PFNA-II in Japan, Injury, Volume 45, Issue 10, 2014, Pages 1624-1631, ISSN 0020-1383,

More information on the study methodology is available on www.ClinicalTrials.gov under the identifying number: NCT00873548.