Gallery of uncommon orthopedic implants: a guide for emergency radiologist

The purpose of this gallery of orthopedic implants was to provide a reference for emergency radiologists to quickly identify uncommon devices in the shoulders, hips, and extremities. The cases presented in this exhibit will include unusual arthroplasties and prostheses as well as bone graft implants (including allograft and autograft). Bone grafts are frequently used for the treatment of bone defects, which may be caused by trauma, infection, or avascularity. Autogenous cancellous, corticocancellous, or cortical bone grafts are often used, either free or vascularized [1]. Alternative bone graft substitutes are also used. An obvious complication of bone grafts is the failure of incorporation. Joint arthroplasty is the most frequently performed orthopedic procedure after fracture fixation. Major indications include degenerative joint disease, inflammatory arthropathy, avascular necrosis, and complicated fractures [6]. Custom orthopedic implants are frequently used for less common indications or for patients with bone tumors. The common hardware complications are infections, loosening, small particle disease/osteolysis, periprosthetic fracture, hardware fracture or dislocation, and recurrent disease, especially in patients with tumors [1]. Many of the devices used by orthopedic surgeons are infrequently seen in everyday radiology practice. With such variations, correct recognition of the prosthetic devices and their complications is very important. The goal of this exhibit was to familiarize the radiologist with both the normal and abnormal appearance of many atypical orthopedic implants. It is important to understand the purpose and proper function of a device, but not necessarily important to describe every device by its proper brand name. Although this exhibit is not meant to be inclusive of every unusual orthopedic implant, we will present multiple examples of orthopedic hardware involving the shoulder, humerus, elbow, forearm, wrist, hand, pelvis, hip, femur, knee, tibia, ankle, and foot that are not likely seen in everyday practice [7]     

Coralline hydroxyapatite bone graft substitutes in a canine metaphyseal defect model: radiographic-biomechanical correlation

Radiographic and biomechanical assessment of a new type of bone graft substitute derived from reef-building sea coral was performed in a canine metaphyseal defect model. Blocks of this material and autogenous iliac crest graft were implanted, respectively, into the right and left proximal tibial metaphyses of eight dogs. Qualitative and quantitative radiographic evaluation was performed in the immediate postoperative period and at 6 months after surgery. Biomechanical testing was carried out on all grafts following harvest at 6 months, as well as on nonimplanted coralline hydroxyapatite and autogenous iliac cancellous bone. In contrast to autografts, incorporation of coralline implants was characterized by predictable osseous growth and apposition with preservation of intrinsic architecture. Greater percent increase in radiographic density, higher ultimate compressive strength, and lower stiffness with incorporation were documented advantages of coralline hydroxyapatite over autogenous graft. Densitometric measurements correlated moderately with strength for both types of graft material (r=-0.65). These promising results have important implications to the clinical application of coralline hydroxyapatite bone graft substitutes as an alternative to autogenous grafting.Presented in part at the 29th Annual Meeting of the Orthopaedic Research Society, Anaheim, California, March 8–10, 1983     

Lateral cephalometric radiograph for the planning of maxillary implant reconstruction

OBJECTIVE: To present a simple and objective method for the planning of maxillary implant reconstruction with autogenous bone graft in maxilla atrophy. METHODS: Lateral cephalometric radiographs were performed with a metallic marker placed inside an acrylic-coated model, followed by cephalometric studies, to predict the most adequate grafting method for maxillary reconstruction in 13 edentulous patients (2 males and 11 females) whose age ranged from 27 to 47 years (mean age 37.9 years). RESULTS: It was possible to predict the type of maxillary reconstruction in all patients. Onlay graft was used in 12 patients. One patient was submitted to LeFort I reconstruction with interpositional graft. After 8 months, the patients received a total of 95 standard implants. The success rate was 94.7% with loss of five implants. Rehabilitation was performed with protocol-type prostheses. All patients have been followed for more than 18 months since osseointegration. CONCLUSIONS: This simple and objective method provided a useful contribution to maxillary reconstruction, and to the functional and aesthetic rehabilitation of the patients.     

Tibial bone bridge and bone block fixation in double-bundle anterior cruciate ligament reconstruction without hardware: a technical note

Current techniques for tibial graft fixation in four tunnels double bundle (DB) anterior cruciate ligament (ACL) reconstruction are by means of two interference screws or by extracortical fixation with a variety of different implants. We introduce a new alternative tibial graft fixation technique for four tunnels DB ACL reconstruction without hardware. About 3.5 to 5.5 cm bone cylinder with a diameter of 7 mm is harvested from the anteromedial (and posterolateral) tibial bone tunnel (s) with a core reamer. The anteromedial (AM) and posterolateral (PL) hamstring tendon grafts (or alternatively tendon allografts) are looped over an extracortical femoral fixation device and cut in length according to the total femorotibial bone tunnel length. The distal 3 cm of each, the AM- and PL bundle graft are armed with two strong No. 2 nonresorbable sutures and the four suture ends of each graft are tied to each other over the 2 cm wide cortical bone bridge between the tibial AM and PL bone tunnel. In addition the AM- and/or PL bone block which was harvested at the beginning of the procedure is re-impacted into the two tibial bone tunnels. A dorsal splint is used for the first two postoperative weeks and physiotherapy is started the second postoperative day. The technique is applicable for four tunnels DB ACL reconstruction in patients with good tibial bone quality. The strong fixation technique preserves important tibial bone stock and avoids the use of tibial hardware which knows disadvantages. It does increase tendon to bone contact and tendon-to-bone healing and does reduce implant costs to those of a single bundle (SB) ACL reconstruction. Revision surgery may be facilitated significantly but the technique should not be used when bony defects are present. In case of insufficient bone bridge fixation or bone blocks hardware fixation can be applied as usual. Not supported by outside funding or grant(s): No benefits in any form have been received, or will be received, from a commercial party related directly or indirectly to the subject of this article. The study complies with the current laws of the country, in which it was performed.     

Comparison of polylactide screw and expansion bolt in bioabsorbable fixation with patellar tendon bone graft for anterior cruciate ligament rupture of the knee A preliminary study

In a preliminary study, 24 patients with rupture of the anterior cruciate ligament (ACL) were operated on using implants made of self-reinforced poly-l-lactide (SR-PLLA). The operation method was outside-in bone-tendon-bone reconstruction. In 10 patients the fixation was made with an SR-PLLA screw with a diameter of 6.3 mm, in 12 with an SR-PLLA expansion plug with a diameter of 6.0 mm, and in two cases both implants were used, but these cases were excluded from comparison. The purpose of the study was to evaluate and compare the use and fixation results of these two implants. The follow-up time averaged 3.2 years. Twenty patients attended follow-up. On subjective evaluations, seven of the eight patients following SR-PLLA screw fixation and six of the ten after expansion plug fixation regarded their knee as normal or nearly normal. Arthrometric testing showed the side-to-side difference to average 2. 9 mm following SR-PLLA screw fixation and 2.6 mm after expansion plug fixation (NS). Six of the patients had giving-way symptoms (two after screw fixation and four after plug fixation). The pivot shift test was slightly positive in two patients and positive in one patient after SR-PLLA screw fixation, and in three knees slightly positive and in another three knees positive following expansion plug fixation. Radiography showed variation in the location and orientation of the bone channels. Magnetic resonance imaging was performed in seven cases, and in two cases an edema was found in the tendon of the anterior cruciate ligament graft and in six cases the implants were visible. No statistical difference in results between the SR-PLLA screw and SR-PLLA expansion bolt was noted. Fixation with expansion plug seems technically more challenging, with a tendency to inferior results compared to screw fixation. In the absorbable fixation of a bone-tendon-bone graft there are no metallic artifacts on magnetic resonance imaging and no need to remove the fixation material regarding the revision surgery.     

Coralline hydroxyapatite bone graft substitutes in a canine diaphyseal defect model: radiographic features of failed and successful union

Radiographic and densitometric evaluation of a new type of bone graft substitute derived from reef-building sea coral via a hydrothermal chemical exchange process was undertaken in a canine diaphyseal defect model. Comparably sized blocks of this material and autogenous iliac cortical-cancellous graft were implanted into the respective radial diaphyses of seven dogs. Qualitative and quantitative radiographic assessment was performed during the immediate postoperative period and at 3 months following surgery. Significant complications were observed radiographically in over half of the coralline implanted limbs, including failed union, graft fracture, and loosening of internal fixation hardware. No significant difference was noted in degree of native osseous ingrowth between the implants and the autografts, and the latter exhibited a higher success rate. Radiographic film densitometry was found not to be reliably predictive of coralline implant behavior in the individual case. It is concluded that coralline hydroxyapatite bone graft substitutes appear to offer no particular advantage over autogenous grafts in the management of diaphyseal defects, although further investigation is warranted since other factors may be responsible for the unfavorable findings in this study.This work has been presented at the 34th Annual Meeting of The Association of University Radiologists. Hartford, Connecticut, May 4–9, 1986     

Augmentation procedures of the jaw in patients with inadequate bone for dental implants: radiographic appearance

Dental implants, metallic posts surgically imbedded in the jaw to support dental prostheses, have provided an attractive alternative to standard removable dentures. Some patients, however, have insufficient bone to accommodate these implants. In this setting, a number of surgical procedures are available to augment the bone in the jaw. It is important for radiologists to be familiar with these procedures because the altered anatomy can be a source of confusion to the unwary. The objective, therefore, was to describe these procedures and their radiographic appearances.     

Bone graft substitutes in sports medicine

Bone graft substitutes are used commonly in orthopedic surgery as an alternative to autograft bone. Autograft bone has the advantages of being osteoconductive, osteoinductive, and osteogenic. However, the quantity of autograft bone available is limited in a given patient and the harvest of autograft bone has been associated with significant morbidity. Bone graft substitutes have become available in an attempt to address these issues and have found widespread use in many areas of orthopedic surgery including sports medicine. The various categories of bone graft substitutes are reviewed here, with an examination of their biologic mechanism of action. Clinical evidence to support their use is also reviewed, with a focus on sports medicine applications.     

Bone tunnel enlargement after anterior cruciate ligament reconstruction: fact or fiction?

Radiographic enlargement of bone tunnels following anterior cruciate ligament (ACL) reconstruction has been recently introduced in the literature; however, the etiology and clinical relevance of this phenomenon remain unclear. While early reports suggested that bone tunnel enlargement is mainly the result of an immune response to allograft tissue, more recent studies imply that other biological as well as mechanical factors play a more important role. Biological factors associated with tunnel enlargement include foreign-body immune response (against allografts), non-specific inflammatory response (as in osteolysis around total joint implants), cell necrosis due to toxic products in the tunnel (ethylene oxide, metal), and heat necrosis as a response to drilling (natural course). Mechanical factors contributing to tunnel enlargement include stress deprivation of bone within the tunnel wall, graft-tunnel motion, improper tunnel placement, and aggressive rehabilitation. Graft-tunnel motion refers to longitudinal and transverse motion of the graft within the bone tunnel and can occur with various graft types and fixation techniques. Aggressive rehabilitation programmes may contribute to tunnel enlargement as the graft-bone interface is subjected to early stress before biological incorporation is complete. Further basic research is required to verify the effect of the various proposed factors on the etiology of bone tunnel enlargement. We recommend that routine follow-up examinations after ACL reconstruction should include the measurement of bone tunnel size in order to contribute to a better understanding of the incidence, time course, and clinical relevance of this phenomenon. Improved and more anatomical surgical fixation techniques may be useful for the prevention of bone tunnel enlargement.     

高原地区陈旧性腕舟状骨骨折治疗方法的选择

目的：在高原地区，选择更为有效的腕舟状骨陈旧性骨折的治疗方法。充分发挥骨膜移植的膜内化骨作用。方法：分别应用单纯植骨内固定，带血管蒂桡骨条移植内固定及带血管蒂骨膜面桡骨条髓内移植内固定方法（ｔｈｅｖａｓｃｕｌａｒｉｚｅｄｒａｄｉｕｓｅａｎｄｕｐｓｅｔｐｅｒｉｏｓｔｅａｌｆｌａｐｓｇｒａｆｔ，ＶＲＰＦＧ）治疗舟状骨陈旧性骨折８例，１２例及１６例，共３６例，并对上述方法的疗效进行了比较研究，结果：术后     

Bone graft materials and synthetic substitutes

Bone graft materials quickly are becoming a vital tool in reconstructive orthopedic surgery and demonstrate considerable variability in their imaging appearance. Functions of bone graft materials include promoting osseous ingrowth and bone healing, providing a structural substrate for these processes, and serving as a vehicle for direct antibiotic delivery. The three primary types of bone graft materials are allografts, autografts, and synthetic bone graft substitutes.     

Imaging of the postoperative spine

Spinal instrumentation techniques have expanded dramatically during the past several decades, but the search for the perfect operative approach and fixation system continues. Fixation devices are designed for the cervical, thoracic, lumbar, and sacral segments using anterior, posterior, transverse, videoarthroscopic, and combined approaches. In most cases, bone grafting also is performed, because instrument failure occurs if solid bony fusion is not achieved. Radiologists must understand the operative and instrumentation options. Knowledge of expected results, appearance of graft material, and different forms of instrumentation is critical for evaluating position of implants and potential complications associated with operative approaches and spinal fixation devices.     

Mandibular erosion from silastic implants: evaluation with a dental CT software program.

Silastic implants used to augment the chin during cosmetic surgery may cause erosive bone changes and complications. We describe the radiologic appearance of these changes and the dental CT reformatting programs by which they may be assessed. Multiplanar CT scans of four patients with Silastic chin implants were evaluated retrospectively for implant density, presence and size of bone defects, relationship of defects to root apices, relationship of defects to mental foramen, and associated findings. The dental CT software program was instrumental in delineating the relationship between the bone defects and the root apices.     

上颌种植体边缘骨吸收的RVG测量分析

目的 :探索放射直视影像 (RVG)对上颌种植体边缘骨吸收进行测量分析的临床应用。方法 :3 2例患者的 5 4枚上颌种植体 ,分别于负载前、负载后 1年和 2年拍摄RVG ,观察和测量种植体边缘骨吸收变化 ,统计学分析种植体在不同时期测量值的一致性。结果 :上颌种植体边缘水平骨吸收于负载后 1年平均 0 .3 6mm ,负载后 2年平均为 0 .87mm ;垂直骨吸收于负载后 1年平均为 0 .97mm ,负载后 2年平均为 1.18mm。t检验显示种植体在不同时期测量值两者间比较差异无显著性意义 (P >0 .5 )。结论 :RVG在对上颌种植体边缘骨吸收观察中的应用值得肯定     

Bone cysts containing silicone particles in bones adjacent to a carpal silastic implant

Silastic implants for a wide variety of medical purposes are in current and frequent use worldwide. Only recently there have been reports of the migration of silicone to the surrounding tissues via lymphatics. In the present material of nine cases with carpal implants followed for more than two years, bone cysts developed in the surrounding bones on five occasions. The only cysts so far investigated thoroughly contained foreign body reaction, and silicone could be detected by electron probe microanalysis. A long-term follow-up is suggested whenever these implants are used.     

牙种植体挤压植人后早期界面骨骨密度的X线影像分析

目的观察牙种植体挤压植入后界面骨的骨密度变化。方法在小型猪双侧前磨牙区挤压植入CompressR种植体(IGZ)。拍摄种植体/骨的数码X线根尖片影像。垂直于种植体长轴提取分析平面,统计分析基础骨密度分别与挤压后的骨密度和骨密度变化区域的相关性。结果挤压后的骨密度增加,基础骨密度与挤压后骨密度的相关系数r=0.8,P=0.00,与骨密度变化区域的相关系数r=-0.49,P=0.00;在同一分析平面种植体两侧的骨组织配对,基础骨密度与骨密度变化区域负相关占79.2%。结论骨挤压增加种植体界面骨的密度,提高初期稳定性。手术前的骨密度分析有助于种植方案的制定,植入前的基础骨密度影响种植体的稳定性;相同挤压距离下基础骨密度越大初期稳定性越好,但疏松骨质较密质骨能耐受更大的挤压距离。     

Sinus lift procedure of the maxilla in patients with inadequate bone for dental implants: radiographic appearance

OBJECTIVE: Dental implants have gained popularity for treating edentulism, but some patients develop jaw atrophy, which leaves insufficient bone for implants. To treat these patients, the sinus lift procedure, which augments bone, was developed. Altered anatomy from this procedure has an unusual radiographic appearance, confusing those unfamiliar with it. We describe the sinus lift procedure and its radiographic appearance. CONCLUSION: With knowledge of this surgery and some of its pitfalls, radiographs can be more easily and accurately interpreted.     

Graft choice and graft fixation in PCL reconstruction

Several grafts and several fixation techniques have been introduced for PCL reconstruction over the past years. To date, autograft and allograft tissues are recommended for PCL reconstruction, whilst synthetic grafts should be avoided. Autograft tissues include the bone-patellar tendon-bone graft, the hamstrings and the quadriceps tendon. Allograft tissues are increasingly being used for primary PCL reconstruction. The use of allograft tissues requires a number of formal prerequisites to be fulfilled. Besides the previous mentioned graft types allograft tissues include Achilles and tibialis anterior/posterior tendons. To date no superior graft type has been identified. Several techniques and devices have been used for fixation of a PCL replacement graft. Most of these were originally developed for ACL reconstruction and then adapted to PCL reconstruction. However, biomechanical requirements of the PCL differ substantially from those of the ACL. To date, requirements for PCL graft fixations are not known. From a systematic approach femoral graft fixation can either be achieved within the bone tunnel (nearly anatomic) with an interference screw or outside the bone tunnel on the medial femoral condyle using a staple, an endobutton or a screw. Tibial graft fixation can be achieved either with an interference screw in the bone tunnel or with a staple, screw/washer or sutures tied over a bone bridge outside the bone tunnel (extra-anatomic). An alternative fixation on the tibial side is the inlay technique that reduces the acute angulation of the graft at the posterior aspect of the tibia. Further research is necessary to identify the differences between the various fixation techniques.     

Autologous chondrocyte implantation in knee joint: MR imaging and histologic features at 1-year follow-up

PURPOSE: To evaluate magnetic resonance (MR) imaging features of autologous chondrocyte implantation (ACI) grafts and compare these with graft histologic features 1 year after ACI for treatment of femoral condylar defects. MATERIALS AND METHODS: This study was approved by the regional ethics committee, and all patients gave informed consent. Forty-one patients (mean age, 35 years; 30 men, 11 women) underwent ACI for treatment of femoral condylar defects. One year later, knee joint MR imaging and graft biopsy were performed. Graft biopsy results were categorized into those showing hyaline, mixed fibrohyaline cartilage, fibrocartilage, and fibrous tissue. Standard T1-, T2-, T2*-, and intermediate-weighted sequences were performed, as well as three-dimensional (3D) fast low-angle shot (FLASH) and double-echo steady-state sequences for cartilage assessment. ACI grafts were assessed for signal intensity (with FLASH sequence), thickness, overgrowth, surface smoothness, integration to adjacent cartilage and underlying bone, bone marrow edema underneath graft, and contour of bone underneath graft. MR images were assessed by two observers, first independently and then in consensus. MR imaging findings were correlated with histologic findings. RESULTS: All 41 grafts were present at 1-year follow-up. The graft consisted of hyaline cartilage in four, mixed fibrohyaline cartilage in 10, fibrocartilage in 25, and fibrous tissue in two cases. Graft signal intensity was virtually always lower than adjacent normal cartilage signal intensity, and there was no relationship between graft signal intensity and histologic appearance (P = .34). Graft thickness (P = .83), overgrowth (P = .69), surface smoothness (P = .28), and integration with adjacent cartilage and underlying bone (P = .90); edema in bone marrow underneath graft (P = .63); and bone contour underneath graft (P = .94) at MR imaging had no correlation with graft histologic appearance. Graft overgrowth (n = 16; 39%) and edema-like signal in bone marrow underneath graft (n = 23; 56%) were common. The origin of graft overgrowth remains unclear. CONCLUSION: With the methods presented here, MR imaging findings cannot predict ACI graft histologic features, and graft histologic appearance determined at biopsy was not related to graft signal intensity, graft thickness, overgrowth, surface smoothness, integration with adjacent cartilage or underlying bone, signal intensity change in underlying bone marrow, or underlying bone contour. Overgrowth and bone marrow changes underneath the graft were common.     

The pathology of total joint arthroplasty

The clinical results of total joint arthroplasty are usually excellent, but surgeons, radiologists, and pathologists are often called upon to evaluate, in one way or another, the stability of the implants. These evaluations are aided by an understanding of the basic pathophysiology of total joint arthroplasty. The first part of this two-part review, will summarize the mechanisms whereby total joint implants achieve fixation. The second part will describe and illustrate the most important mechanisms of implant loosening. The ”gold standard” for hip and knee arthroplasty is to use polymethylmethacrylate bone cement to anchor the implant to bone, but the optimal surface texture of cemented implants is controversial. Some surgeons advocate a rough implant texture to facilitate bonding between implant and cement; other surgeons prefer a smooth, polished implant to minimize abrasion of cement. Implant loosening can be initiated by particles of cement generated at either the implant/cement, or cement/bone interface. Uncemented implants with porous metal surfaces achieve a variable amount of bone ingrowth, but some designs have excellent clinical results. Maximal bone ingrowth usually occurs along surfaces that are relatively close to cortical bone. Implants with bioactive coatings, such as hydroxyapatite achieve rapid bone apposition. The amount of bone that persists on uncemented implants long-term is determined by many variables, inlcuding the quality of the coating, the overall implant design, and factors that influence local bone remodeling. Received: 29 March 1999 Revision requested: 5 May 1999 Revision received: 7 June 1999 Accepted: 9 June 1999