No abstract

Introduction Acetabular cup placement is an important modifiable factor determining complication rates like aseptic loosening and hip dislocation related to faulty cup placement, which by standard method is largely dependent upon eyeballing and surgeon's judgment. We evaluated a self-designed, low-cost, patient-specific acetabular jig to guide cup placement in total hip arthroplasty in comparison to conventional technique. Methods It was a prospective randomized control study. Thirty-six patients were categorized into group-A & group-B. In group-A, virtually designed acetabular jig was 3 Dimensional (3D) printed and used intra-operatively to guide cup placement. In group-B, the standard method of cup placement was used. Acetabular cup placement was evaluated on postoperative x-rays and compared between two groups. Results In group-A, angle of anteversion were significantly in centre of range of safe zone as compared to group B in which hip is maximally stable with more precision in creating hip centre as compared to group-B without any significant(p = 0.325) increase in surgical time or blood loss. Conclusion Computed tomography (CT) scan based virtual pre-operative templating and cup placement guided by virtually designed, patient-specific acetabular jig is a low-cost tool with a short learning curve which can be designed and made available easily. It is a useful tool in decreasing chances of malpositioning of cup and recreates hip centre close to anatomical one especially in cases where anatomy has been distorted such as bony ankylosis and developmental dysplasia of hip.

Surgical treatment of femoroacetabular impingement (FAI) focuses on improving the clearance for hip motion and alleviation of femoral abutment against the acetabular rim. Cam type of impingement is managed by performing an osteochondroplasty to remove the excess impinging bone from the head neck junction, thus improving the head neck offset. This procedure can be done by safe surgical dislocation, arthroscopy assisted mini-open method or all arthroscopy technique. Whatever be the approach, adequate excision of the Cam deformity is necessary to avoid suboptimal results. Under-excision leads to persistent symptoms and progression of disease, while over-excision can lead to weak bone vulnerable to fracture or disturb the labral seal. Various techniques utilized for intra-operative evaluation of amount of excision required described in literature are fluoroscopy, spherometer gauges, intra-operative Computed Tomography (CT) scan, navigation etc. Rapid prototyping, also called as three dimensional (3D) printing, is a technology to create dimensionally accurate model from a computer-assisted design. Accurate physical models can be designed from the medical imaging data like CT scans and 3D printed to aid in various medical applications. Its application in orthopaedic field is on a rise, recently. However, there is no report on utilization of this technique in surgeries for FAI. We have reported a case of Cam type FAI in an eighteen year old boy, which we treated surgically by performing osteochondroplasty using safe surgical dislocation. We did CT based virtual surgical planning to design femoral head and neck jigs, which were 3D printed and used intra-operatively to guide for adequate and optimum excision of bone at head neck junction. We found these customized jigs accurate and useful for the surgery. However, a comparison study with various other techniques is warranted for a detailed research on its usefulness and challenges. The main purpose of this article is to elaborate on the technical steps for designing of jigs for 3D printing to guide in osteochondroplasty surgery for FAI.

Pedicle screws are one the commonest used modality in spinal instrumentation. However, the method of pedicle screw fixation in cervical spine as compared to thoracic and lumbar spine is still technically demanding because it carries the risk of catastrophic damage to the surrounding neurovascular structures We have utilized virtual planning and 3D (3-dimension) printing to develop a patient specific jig to guide the accurate placement of pedicle screws. A patient with bifacetal dislocation C7 over D1 classified as flexion-distraction injury type 3 who was planned for decompression and fusion by posterior instrumentation at C6, C7, D1 and D2 was selected. A CT scan with 1 mm cuts was used to produce DICOM images of the same. Using these DICOM images virtual planning was done on MIMICS and 3 MATICS software to create patient specific jigs. These jigs were then 3D printed using a 3D printer and used for accurate placement of pedicle screws intra-operatively after adequate sterilization. Our procedure is low cost but high technology based. It is simple, accurate, and very cost effective. The technology transfer is very easy and can be adopted easily.

This was a pilot study and we need a large sample size to study accuracy of our acetabular plate design which might avoid intra-operative contouring, decreasing morbidity of patient and prevent wastage of resources in pre-operative planning and computer designing.