A new 3D printed titanium metal trabecular bone reconstruction system for early osteonecrosis of the femoral head

Abstract

Presently, biomechanical support therapy for the femoral head has become an important approach in the treatment of early osteonecrosis of the femoral head (ONFH). Previous studies have reported that the titanium metal trabecular bone reconstruction systems (TMTBRS) achieved satisfactory clinical results for the treatment of early femoral head necrosis. Electron beam melting technology (EBMT) is an important branch of 3D printing technology, which enables the construction of an interface that is required for support of bone in-growth. However, the effect of TMTBRS created using EBMT for clinical applications for early ONFH is still unknown. At present, there are no reports on this topic worldwide. The purpose of this study was to assess the safety of a new 3D printed TMTBRS implant and to evaluate its clinical efficacy in early ONFH.Thirty patients who underwent surgery for ONFH were selected. The stages of ONFH were classified according to the Association Research Circulation Osseus (ARCO) classification. They were followed-up and radiological examination was performed at 6, 12, and 24 months post-surgery to assess TMTBRS stability and bone growth in the bone trabecular holder portion surface. To evaluate hip function, postoperative Harris and Visual Analogue Scale (VAS) scores were used.The postoperative Harris score increased significantly and VAS score decreased significantly at the 12-month follow-up compared to the 24-month follow-up, wherein the Harris score declined slightly and the VAS score was slightly elevated with the aggravation of ONFH. With the passage of time, postoperative improvement rates were 100% for IIA, 70% for IIB, and 0% for IIC. Hip-preserving rates were 100% for IIA, 100% for IIB, and 50% for IIC.The effect of TMTBRS treatment for early ONFH in ARCO IIA and ARCO IIB is satisfactory. However, it is not recommended for a relatively large area of necrosis such as in ARCO IIC.

Figure 1

Electron beam melting technology rapid prototyping equipment (A) and electron beam processing diagram (B).

Figure 2

Trabecular metal structure of titanium metal trabecular bone reconstruction system (A, B). A1 is the bone trabecular holder portion and A2 is the connecting rod.

Figure 3

The split design of the titanium metal trabecular bone reconstruction system. Its chemical composition is in line with the provisions of YY0117.2 (A) Titanium metal trabecular bone reconstruction system split design of the connecting rod with its chemical composition in line with GB/T 13810 in the grades specified by TC4ELI. (B) Titanium metal trabecular bone reconstruction system split design of the bone trabecular holder portion, the intermediate hollow design. Bone induction material with treatment can be implanted in the middle (C).

Figure 4

Trabecular metal-holder SEM Fig, 20× (A), 30× (B), 50× (C), 60× (D).

Figure 5

Physical appearance of bone trabecular holder portion (A) and titanium metal trabecular bone reconstruction system (B).

Figure 6

Anteroposterior (A) and lateral (B) views of the implanted bone in growth and evaluate stress shielding partition schematic.

Figure 7

Imaging evaluation method: according to the method previously proposed by the authors, evaluation was improved, primarily on the basis of necrosis and collapse of self-made 4 grades. THA = total hip arthroplasty.

Figure 8

Characteristics of the patient's condition. The patients included 19 males and 11 females (A) and 14 left hips and 16 right hips (A), with ages ranging from 22 to 54 years (average 41.72 ± 3.56 years). Patients’ ARCO staging indicated 2 hips of stage II A, 26 hips of stage II B and 2 hips of stage II C (B). ARCO = Association Research Circulation Osseus.

Figure 9

Harris and Visual Analogue Scale (VAS) scores. Hip joint function score in patients before and after treatment (A). VAS score in 2 groups of patients before and after treatment (B). Data are shown as means ± standard deviation at the 24^th month. ∗∗P < .01 vs. no treatment.

Figure 10

Preoperative and postoperative x-ray images staging and follow-up for 24 months. Radiographic assessment for 24 months showed that the level I patients are in better condition, and have not reached a final grade of IV.

Figure 11

The rate of improvement and hip preservation. The results showed that postoperative improvement rate was 100% of IIA, 70% of IIB, and 0% of IIC (A). Judging from the 2 sets of statistics, the improvement rate and protection of the hips of IIA and IIB patients were superior to IIC.