Bone defect map of the true acetabulum in hip dysplasia (Crowe type II and III) based on three-dimensional image reconstruction analysis

The high hip center technique (HHC) is considered to be feasible for acetabular reconstruction in patients with DDH, but there is little in-depth study of its specific impact on Crowe type II and III DDH. The purpose of this study was to simultaneously analyze the effect of HHC on bone coverage of the cup (CC) in the acetabular reconstruction of type II and III DDH patients and to propose a map of acetabular bone defects from the perspective of the cup. Forty-nine hip CT data of 39 patients with DDH (Crowe type II and III) were collected to simulate acetabular reconstruction by cup models of different sizes (diameter 38mm–50 mm, 2 mm increment) with the HHC technique. The frequency distribution was plotted by overlapping the portions of the 44 mm cups that were not covered by the host bone. The mean CC of cups with sizes of 38 mm, 40 mm, 42 mm, 44 mm, 46 mm, 48 mm, and 50 mm at the true acetabula were 77.85%, 76.71%, 75.73%, 74.56%, 73.68%, 72.51%, and 71.75%, respectively, and the maximum CC increments were 21.24%, 21.58%, 20.86%, 20.04%, 18.62%, 17.18%, and 15.42% (P < 0.001), respectively, after the cups were elevated from the true acetabula. The bone defect map shows that 95% of type II and III DDH acetabula had posterosuperior bone defects, and approximately 60% were located outside the force line of the hip joint. Acetabular cups can meet a CC of more than 70% at the true acetabulum, and approximately 60% of Crowe type II and III DDH patients can obtain satisfactory CC at the true acetabulum by using a 44-mm cup without additional operations.

Inverted reamer technique for bone grafting of the acetabulum: technical note

Background Socket fixation with bone grafting for dysplastic hips is technically demanding, and inadequate coverage of the socket may cause poor results in patients with severely dysplastic hips. An accurate technique to form a bone graft to fit into the defect is necessary. We aim to introduce the simple method of bone grafting, “inverted reamer technique” in cemented total hip arthroplasty (cTHA). Methods After acetabular preparation with a normal acetabular reamer, the bone graft was prepared from the resected femoral head with the inverted reamer. The graft can be press-fit into the defect of the acetabulum with good compatibility through this method. Then, the bone graft was fixed with 1–3 screws and the socket was implanted with bone cement. Results The “inverted reamer technique” can easily and automatically create a well-fit graft. This method is simple and technically less demanding; it can be performed by every surgeon, including trainee and inexperienced surgeons. Conclusion This method can improve the outcome of cTHA for dysplastic hips by preserving bone stock and increasing bone coverage of the socket implanted in the anatomic position.

Impacted Upper Central Incisors – Frequency and Factors Complicating the Treatment Protocol

Introduction: Eruption of central incisors occurs at a time when the mixed dentition starts to develop and their impaction is mostly a severe esthetic problem.Aim: Our aim was to assess the frequency of impaction of an upper central incisor and to analyse the factors which affect the successful outcome and the protocols for orthodontic treatment in cases of impacted upper central incisors.Materials and methods: In the present study, we used all medical records of 651 patients treated in our private practice over the last 3 years and also the medical records of 18 patients we diagnosed and treated for this problem over the last 8 years.Results: We found the ratio of impacted upper central incisors to be 1.4% as there were more male than female patients affected. There were 2.8% male patients and 0.7% female patients. The most frequent cause of impaction of the upper central incisor was the presence of mesiodentes and supernumerary teeth (55.5%), followed by presence of follicular cysts (44.4%) and odontoma collections (22.2%) or a combination of these.Several approaches have been used in treating the different positions of impacted incisors. It is necessary first to rotate the axle of the incisor and assure its root full bone coverage. We used directly TPA for support. In other patients, we waited for the spontaneous eruption after removal of the etiological factor and in another patient, we used conventional fixed techniques.Conclusions: It is important that dental doctors should monitor the formation of the dentition so that they detect the impacted tooth early in its development.

Bone Coverage around Hydroxyapatite/Poly(L-Lactide) Composite Is Determined According to Depth from Cortical Bone Surface in Rabbits

Composites of unsintered hydroxyapatite (HA) and poly(L-lactide) (PLLA) reinforced by compression forging are biodegradable, bioactive, and have ultrahigh strength. However, foreign body reactions to PLLA and physical irritation can occur when not covered by bone. We aimed to confirm the relationships between the depth of the implanted HA-PLLA threaded pins and the new bone formation. We inserted HA-PLLA composite threaded pins (diameter: 2.0 or 4.5 mm) into the femoral and tibial bones of 32 mature male Japanese white rabbits (weight 3.0–3.5 kg) with the pin head 1 or 0 mm below or protruding 1 or 2 mm above surrounding cortical bone. Eight euthanized rabbits were radiologically and histologically assessed at various intervals after implantation. Bone bridging was complete over pins of both diameters at ~12 weeks, when inserted 1 mm below the surface, but the coverage of the pins inserted at 0 mm varied. Bone was not formed when the pins protruded >1 mm from the bone surface. No inflammation developed around the pins by 25 weeks. However, foreign body reactions might develop if composites are fixed above the bone surface, and intraosseous fixation would be desirable using double-threaded screws or a countersink to avoid screw head protrusion.

Neutralized Dicalcium Phosphate and Hydroxyapatite Biphasic Bioceramics Promote Bone Regeneration in Critical Peri-Implant Bone Defects

The aim of this study was to evaluate the efficacy of bone regeneration in developed bioceramics composed of dicalcium phosphate and hydroxyapatite (DCP/HA). Critical bony defects were prepared in mandibles of beagles. Defects were grafted using DCP/HA or collagen-enhanced particulate biphasic calcium phosphate (TCP/HA/Col), in addition to a control group without grafting. To assess the efficacy of new bone formation, implant stability quotient (ISQ) values, serial bone labeling, and radiographic and histological percentage of marginal bone coverage (PMBC) were carefully evaluated four, eight, and 12 weeks after surgery. Statistically significant differences among the groups were observed in the histological PMBC after four weeks. The DCP/HA group consistently exhibited significantly higher ISQ values and radiographic and histological PMCB eight and 12 weeks after surgery. At 12 weeks, the histological PMBC of DCP/HA (72.25% ± 2.99%) was higher than that in the TCP/HA/Col (62.61% ± 1.52%) and control groups (30.64% ± 2.57%). After rigorously evaluating the healing of biphasic DCP/HA bioceramics with a critical size peri-implant model with serial bone labeling, we confirmed that neutralized bioceramics exhibiting optimal compression strength and biphasic properties show promising efficacy in fast bone formation and high marginal bone coverage in peri-implant bone defects.

Postoperative radiographic evaluation and simulation study for optimal cup placement in high-hip centre total hip arthroplasty

Background: Achieving favourable outcomes in high-hip centre reconstruction in hip dysplasia requires the optimal cup height and size, which can provide sufficient bone coverage for stable cup fixation that fits the anteroposterior acetabular rim without increasing the cup height more than necessary. Methods: We retrospectively reviewed 214 patients who underwent primary total hip arthroplasty (THA) and identified 30 hips with Crowe II ( n = 15) or III ( n = 15) developmental dysplasia of the hip (DDH). We measured the cup-centre-edge angle (cup-CE) and the vertical and horizontal distances from the teardrop. In a simulation study, we examined the cup-CE and optimal cup size by changing the cup height in 5-mm increments over a distance of 15–40 mm above the inter-teardrop line using a 3-dimensional template system. Results: Postoperative radiographic evaluation revealed a mean cup-CE of 19.9° in Crowe II hips and 15.2° in Crowe III hips; the respective mean vertical distances were 26.6 mm and 27.6 mm ( p = 0.511). There was no evidence of cup loosening or lateralisation at a minimum of 7 years (7–11 years) follow-up. Simulation showed that the hip centre needed to be elevated to 20 mm to acquire a cup-CE of more than 0°. More than 10° of cup-CE could be expected by elevating the hip centre to 25 mm in both Crowe II and III. Conclusions: Even in severe DDH, a high-hip centre positioned approximately 25 mm superior to the inter-teardrop line was sufficient to achieve optimal bone coverage, which could lead to more secure cup fixation.

Bone regeneration after alveolar dehiscence due to orthodontic tooth movement – A case report

This article presents the orthodontic treatment of a 15 year old male patient with an Angle class I malocclusion with a class II skeletal base, lower incisor proclination along with a hyperdivergent facial pattern. Such situations that involve camouflage treatment, usually results in further lower incisor proclination which can be reduced to an extent by adding buccal root torque. Placement of additional torque in this case however, resulted in positioning of the root apex of the lower right lateral incisor outside the alveolar housing, although no gingival signs were present. The mechanics were then reversed and at the end of 21 months of treatment, the apices were back within the alveolar housing. A 4-year post-treatment cone-beam computed tomography showed normal bone coverage of the affected tooth; and no clinical signs of gingival pathology were present. Orthodontists should be aware of possible complications of excessively torqueing lower incisors in order to prevent proclination. If root apices are inadvertently moved through the cortex, a good long-term prognosis is possible using orthodontics alone by reversing the mechanics, if no gingival complications are present.