Aims. The proximal tibia (PT) is the anatomical site most frequently affected by primary bone tumours after the distal femur. Reconstruction of the PT remains challenging because of the poor soft-tissue cover and the need to reconstruct the extensor mechanism. Reconstructive techniques include implantation of massive endoprosthesis (megaprosthesis), osteoarticular allografts (OAs), or allograft-prosthesis composites (APCs). Methods. This was a retrospective analysis of clinical data relating to patients who underwent proximal tibial arthroplasty in our regional bone tumour centre from 2010 to 2018. Results. A total of 76 patients fulfilled the inclusion criteria and were included in the study. Mean age at surgery was 43.2 years (12 to 86 (SD 21)). The mean follow-up period was 60.1 months (5.4 to 353). In total 21 failures were identified, giving an overall failure rate of 27.6%. Prosthesis survival at five years was 75.5%, and at ten years was 59%. At last follow-up, mean knee flexion was 89.8° (SD 36°) with a mean extensor lag of 18.1° (SD 24°). In univariate analysis, factors associated with better survival of the prosthesis were a malignant or metastatic cancer diagnosis (versus benign), with a five- and ten-year survival of 78.9% and 65.7% versus 37.5% (p = 0.045), while in-hospital length of stay longer than nine days was also associated with better prognosis with five- and ten-year survival rates at 84% and 84% versus 60% and 16% (p < 0.001). In multivariate analysis, only in-hospital length of stay was associated with longer survival (hazard ratio (HR) 0.23, 95% confidence interval (CI) 0.08 to 0.66). Conclusion. We have shown that proximal tibial arthroplasty with endoprosthesis is a safe and reliable method for reconstruction in patients treated for orthopaedic oncological conditions. Either modular or custom implants in this series performed well. Cite this article: Bone Jt Open 2022;3(9):733–740

Aims. This study aimed to identify the effect of anatomical tibial component (ATC) design on load distribution in the periprosthetic tibial bone of Koreans using finite element analysis (FEA). Methods. 3D finite element models of 30 tibiae in Korean women were created. A symmetric tibial component (STC, NexGen LPS-Flex) and an ATC (Persona) were used in surgical simulation. We compared the FEA measurements (von Mises stress and principal strains) around the stem tip and in the medial half of the proximal tibial bone, as well as the distance from the distal stem tip to the shortest anteromedial cortical bone. Correlations between this distance and FEA measurements were then analyzed. Results. The distance from the distal stem tip to the shortest cortical bone showed no statistically significant difference between implants. However, the peak von Mises stress around the distal stem tip was higher with STC than with ATC. In the medial half of the proximal tibial bone: 1) the mean von Mises stress, maximum principal strain, and minimum principal strain were higher with ATC; 2) ATC showed a positive correlation between the distance and mean von Mises stress; 3) ATC showed a negative correlation between the distance and mean minimum principal strain; and 4) STC showed no correlation between the distance and mean measurements. Conclusion. Implant design affects the load distribution on the periprosthetic tibial bone, and ATC can be more advantageous in preventing stress-shielding than STC. However, under certain circumstances with short distances, the advantage of ATC may be offset. Cite this article: Bone Joint Res 2022;11(5):252–259

µCT images are commonly analysed to assess changes in bone density and architecture in preclinical murine models. Several platforms provide automated analysis of bone architecture parameters from volumetric regions of interest (ROI). However, segmentation of the regions of subchondral bone to create the volumetric ROIs remains a manual and time-consuming task. This study aimed to develop and evaluate automated pipelines for trabecular bone architecture analysis of mouse proximal tibia subchondral bone. A segmented dataset involving 62 knees (healthy and arthritic) from 10-week male C57BL/6 mice were used to train a U-Net type architecture, with µCT scans (downsampled) input that output segmentation and bone volume density (BV/TV) of the subchondral trabecular bone. Segmentations were upsampled and used in tandem with the original scans (10µ) as input for architecture analysis along with the thresholded trabecular bone. The analysis considered the manually and U-Net segmented ROIs using two available pipelines: the ITKBoneMorphometry library and CTan (SKYSCAN). The analyses included: bone volume (BV), total volume (TV), BV/TV, trabecular number (TbN), trabecular thickness (TbTh), trabecular separation (TbSp), and bone surface density (BSBV). There was good agreement for bone measures between the manual and U-Net pipelines utilizing ITK (R=0.88-0.98) and CTan (R=0.91-0.98). ITK and CTan showed good agreement for BV, TV, BV/TV, TbTh and BSBV (R=0.9-0.98). However, a limited agreement was seen between TbN (R=0.73) and TbSb (R=0.59) due to methodological differences in how spacing is evaluated. This U-Net/ITK pipeline seamlessly automated both segmentation and quantification of the proximal tibia subchondral bone. This automated pipeline allows the analysis of large volumes of data, and its open-source nature may enable the standardization of stereologic analysis of trabecular bone across different research groups

The bone mineral density (BMD) can be measured by dual energy X-ray absorptiometry (DEXA) accurately and precisely. BMD measurements of proximal tibia, where the structure is dominantly trabecular bone, were made on 45 normal women, aged 24–91 (52.0±14.2) years, and on 46 normal men, aged 20–71 (53.7±15.5) years. The precision of BMD measurements of proximal tibia, expressed as the coefficient of variation, was smaller than 4%. Throughout this cross-sectional study, the following results were acquired. The mean BMD in male is higher than that in female. The BMD show a decrease with age at different rates in women and men. The BMD in both genders is found to increase with body weight. A positive correlation is found between the BMD and body height in women, not in men. In right proximal tibia, the BMD of medial regions are higher than that of lateral regions significantly. Our study also demonstrates that the excellent symmetry of the BMD of the bilateral proximal tibias in both genders, but not in men with age less than 50 years old. Through the study of BMD in proximal tibias using the DEXA, it may reflect the bone reactions to many factors, such as age, sex, body weight & height, and weight bearing etc. Such a kind of study might be an useful adjuvant tool to assess the bone remodelling around the knee joint following the different surgical procedures such as total knee arthroplasty or high tibial osteotomy and might predict the future surgical outcomes

Introduction. 47 yrs male patient had a prior history. 2005 Fx. proximal tibia (open Fx.). 2007 Metal removal. 2008 Arthroscopic debridement (2 times). He visited out hospital with severe pain and tenderness X-ray (Fig 1) and MRI (Fig 2) findings as follows. Conclusively, He had a chorinic osteomylitis of proximal tibia with soft tissue absess. 1st Surgery. I did arthroscopic debridement Arthroscopic finding shows synovitis, meniscus tear and chondromalacia. I did meticulous debridement (irrigation & curettage). 2nd Surgery. He did primary total knee arthro-plasty instead of two-stage exchange arthroplasty in may, 2010 at the another hospital. 3rd Surgery. After 7 months since he had did total knee arthroplasty, he visited to my hospital again with sudden onset of painful swelling & heating sensation. 4th Surgery. I did second stage reimplantation for infected total Knee arthroplasty after 7 weeks. Now he got a pain relief & ROM restroration. Results. Follow up 12 months X-ray showing all implants to be well-positioned and stable. Clinically, there was no implant considered to be loose. In this study, the knee society and functional scores at final follow up were 82 and 68. Conclusion. The infection after sequales of open proximal tibia fracture is treated by two-stage exchange total knee arthroplasty instead of primary total knee arthroplasty. Two-stage reimplantation of an infected total knee arthroplasty using a static antibiotic-cement spacer achieved an infection control and improvement in the clinical result 3). We use an antibiotic-loaded cement spacer(ALACS) preserved knee function between stages, resulting in effective treatment of infection, facilitation of reimplantation, and improved patient satisfaction 1). The principle surgical technique used for two-stage revision of infected total knee including: (1) exposure, (2) implant removal and debridement, and (3) construction of both static and mobile antibiotic spacers 2

Pupose: The purpose of this study was to analyze the outcome of proximal tibia osteoarticular allografts after tumor resections. Material amd Methods: We performed a retrospective study over 58 patients in which a proximal tibia allograft reconstruction was undertaken. All patients were followed for a minimum of 5 years and allografts survival from the date of implantation to the date of revision or the time of the latest follow-up was determined with the use of the Kaplan-Meier method. In all patients, the patellar tendon from the host was reattached by suturing to overlapped donor flaps. Patients were clinically evaluated with the MSTS score system. Results: The global rate of allograft survival was 65% +/− 12% (+/− 2 SE) at five and ten years, with no significant difference between patients who received chemotherapy and those who did not. Allografts needed to be removed in twenty patients due to 12 infection, 4 local recurrences and 4 fractures. Active knee extension was restored in all patients with an average functional score of 26.3 points. Discussion: Survival analysis showed that 65% of proximal tibia osteoarticular allograft reconstructions remain stable at five and ten years. Patellar tendon reconstruction with allogeneic tissue in proximal tibia allograft restores active knee extension with an excellent functional result. Despite the incidence of complications, proximal tibia osteoarticular allografts continue to be a very valuable reconstructive procedure for large defects after resection of bone tumors

Introduction. Precise implant matching with a resected bony surface is a crucial issue to ensure a successful total knee arthroplasty (TKA). Extremely undersized or oversized components should be avoided. Therefore, we should measure the exact anthropometric data of the resected bony surface preoperatively or intraoperatively. The purpose of this study was to intraoperatively analyze the exact anthropometric proximal tibial data of Japanese patients undergoing TKA and correlate these measurements to the dimensions of current prosthetic systems. Patients and Methods. Three hundred and seventy-three knees in 299 Japanese patients were included in this study. There were 246 women and 53 men with a mean age of 74 (range: 63–85) years. All TKAs were performed by 3 senior surgeons (TS, AK, and NM). The bone cut in the proximal tibia was made perpendicular to the longitudinal axis of the tibia in the frontal plane. Intraoperative measurements of the proximal tibial cut surface were taken after proximal tibial preparation. Akagi's line (center of the posterior cruciate ligament tibial insertion to the medial border of the patellar tendon attachment) was adopted as the anteroposterior axis line of the proximal tibia. A mediolateral (ML) line was drawn perpendicular to Akagi's line. Then, anteroposterior (AP), lateral anteroposterior (lAP), and medial anteroposterior (mAP) lines were drawn as shown in Figure 1. Results. There was a significant positive correlation between lAP and ML dimensions. Although there also was a significant positive correlation between lAP and mAP dimensions, individual knees presented much scatter (Figure 2). The lAP dimension was smaller than the mAP dimension in all knees by a mean of 4.5 ± 1.9 mm. The proximal tibia exhibited asymmetry between the lateral and medial plateaus. The recent data of 177 knees indicated that Akagi's line was located 1.0 ± 1.2 mm medial to the AP line. A comparison of the morphologic data and the dimensions of the implants, one of which was a symmetric tibial component (NexGen: Zimmer, Warsaw, Indiana), and the other asymmetric (Genesis II: Smith & Nephew, Memphis, Tennessee), indicated that an asymmetric tibial component could be beneficial in maximizing the coverage of the tibial plateau. However, the size variation of the asymmetric tibial component was poor and the lAP and mAP dimensions showed much scatter; thus, we should measure the proximal tibia and choose the proper tibial component during surgery. Conclusions. This study provides important reference data that may be useful for designing proper tibial components for Japanese patients

Aim. In patients with bone sarcoma, placing mega prostheses in the proximal tibia is associated with high rates of infection. In studies with small numbers of patients and short follow-up periods, silver-coated mega prostheses have been reported to lead to reduced infection rates. To the best of our knowledge, this study is the largest one that has compared the infection rates with titanium versus silver-coated mega prostheses in patients treated for sarcomas in the proximal tibia. Method. The infection rate in 98 patients with sarcoma or giant cell tumour in the proximal tibia who underwent placement of a titanium (n = 42) or silver-coated (n = 56) mega prosthesis. *. was assessed, along with the treatments administered for any infection. Results. As the primary end point of the study, the rates of infection were 16.7% in the titanium group and 8.9% in the silver group, resulting in 5-year prosthesis survival rates of 90% in the silver group and 84% in the titanium group. Overall, seven of 56 patients in the silver group (12.5%) developed periprosthetic infection. Two patients became infected after revision surgery due to mechanical failure of the prosthesis. In the titanium group, one patient developed a periprosthetic infection after revision surgery (which was carried out in 50% of patients) due to a mechanical prosthetic failure, leading to an overall infection rate of 19.0% (eight of 42). Overall, nine of 12 (75%) periprosthetic infections in the two groups occurred within the first 2 years postoperatively, if later revision surgery due to mechanical failure was not necessary. Whereas three of the eight patients in the titanium group (37.5%) ultimately had to undergo amputation due to infected proximal tibia replacement, these mutilating surgical procedures were necessary in the silver group in only one patient (14.3%). In the titanium group, two-stage revision surgery with a temporary antibiotic-impregnated cement spacer was ultimately successful in four of eight patients (50.0%), but this procedure was necessary in only one patient in the silver group (14.3%). Conclusions. The use of silver-coated prostheses reduced the infection rate in a relatively large and homogeneous group of patients. In addition, less aggressive treatment of infection was possible in the group with silver-coated prostheses

To try to find a solution to the high complication rate associated with harvesting bone graft from the iliac crest, a retrospective and prospective study was undertaken to document bone grafting from the proximal tibia in 37 adult patients undergoing a variety of foot procedures. The hospital charts of 17 patients were evaluated retrospectively for complications (mean follow-up of 27 months), while 20 patients were assessed prospectively by means of a questionnaire (mean follow-up of 7 months). There was an overall complication rate of 10.8%, 5.8% in the retrospective group and 15% in the prospective group. All complications were minor and resolved. Although our overall complication rate is slightly higher than in similar studies, ours is the only prospective study that actively followed the healing of patients’ donor sites. We recommend the proximal tibia as an alternative harvest site. Contrary to popular belief, the proximal tibia provides a large volume of cancellous graft material

Introduction: The use of allograft prosthetic composite (APC) of the proximal tibia offers advantages over prosthetic replacement or osteoarticular graft with a better functional outcome since the possibility of a careful soft tissue reconstruction;. Materials and Methods: From 1994 to 2002, 62 APC of the proximal tibia were performed in our department after bone tumor resection (56 malignant bone tumors, 4 cases of previously failed knee implant and 2 stage 3 benign tumors). The patients median age was 18 yrs (range: 11–77 yrs) and the mean resected length was 13.2 cm (range: 8.5–28 cm). The median follow up was 59 months (range: 13–137 months). Results: In three patients (4,8%) a recurrence was reported at 22, 33 an 40 months and amputation was performed. Infection was reported in 15 patients (24.2%): 2 early infections (healed with surgical debridment), 1 femoral stem septic loosening (treated with early revision with cemented stem); in 8 cases removal of the infected APC was required followed by implant of a new prosthetic device after cement spacer; two infections did not healed and patient underwent amputation; in two cases a good functional result was achieved removing the infected graft and covering the proximal tibia with cement and no other surgery was required. Non union of the graft was observed in 8 patients (12.9%): in 4 patients autologous bone grafting was necessary to heal the osteotomy line. In other 3 cases non union was associated with graft fracture. In one case non union was associated with tibial stem loosening and revision of the whole implant was done. Polyethylene wear was assessed in 5 patients (8%) and revision of the polyethylene components was always required. Nine patellar tendon rupture (14.5%) were assessed and repaired was performed in seven cases. The functional outcome of 42 patients with more than two years of follow up was excellent in 25 cases, good in 13, fair in 2 and poor in 2. Discussion: APC of the proximal tibia is an effective alternative to osteoarticular graft and modular prosthesis because it allows good to excellent results in most of the patients (90.4%). The major concern is infection rate (24.2%) that usually lead to amputation (80%). Non union does not usually represent a problem because it’s tendency to spontaneous or bone grafting induced healing. Aseptic loosening of the tibial or femoral stem is rare. Patellar tendon rupture rate (14.5%) is similar to modular prosthetis rate and can be lowered using a femoral component with patellar groove

Since the introduction of carving skis, the injuries of the tibia is changing from simple fractures of the diaphyse to complex fractures of the epiphyses, according to high energy traumas. There are no studies about results of the treatment and consequences after winter sport accidents. Method: Prospective documentation of all proximal tibia fractures after winter sport accidents, which were treated between 01.12.2006 and 31.04.2009 in the Trauma Department of the Klinikum Garmisch-Parten-kirchen, Germany. X-Rays and CT scans were classified according to the AO –Classification. Operations, complications, co-injuries and the hospital stay were analysed. We performed the Lysholm score, WOMAC Knee-score and the Tegner-index on the day of injury, 6 months, 12 months, and 2 years after injury. Results: 78 patients had a proximal tibia fracture following a skiing accident, 36 Male and 42 female. All except two patients had a monotrauma of the proximal tibia. Mean age 46 ± 15 years. 17 types A.1.3, 41 types B and 18 types C3 fractures. 4 patients developed a compartment syndrome, one patient had a lesion of the n. peroneus. 65 patients were operated in our hospital. In 8 patients we performed a conservative treatment. The mean hospital stay was 12 ± 7.5 days. In 15 patients a menisci reconstruction was necessary. 6 patients had a postoperative complication: 3 thromboses, 2 cardiac decompensations, 1 wound healing problems. By now 42 patients were ready for follow-up. So far the mean follow-up time is 13.8 months. The Lysholm score was at 12 months (n= 22) 78 ± 20 points. The Tegner score was pre-injury 6.2 ± 1.1 and 12 months post-injury 4.1 ± 1,8. The results of the WOMAC score show an improvement in the subcategories pain and function in all patients. In the subcategory stiffness only the type A and B fractures show an improvement during the follow-up. Conclusion: The proximal tibia joint fractures are a serious injury. The most patients’ activity level is tremendously reduced. The major problem after one year seems to be the ligament instability of the knee. A beginning knee arthritis after one year becomes relevant only in the type C fractures. More effort for the prevention of the proximal tibia fractures while skiing is necessary

Modular endoprostheses are commonly used for reconstruction of proximal tibia defects after bone tumor resection and patellar tendon reattachment directly on the prosthesis represent an issue frequently ending in extension lag. Allograft-prosthesis composite implants theoretically provide the advantages of prosthetic implants (joint stability, mechanical resistance and long term durability) and the advantages of massive allograft reconstruction (bone stock mantainance and biologic reattachment of patellar tendon). From 1997 to 2007 19 patients (mean age: 39±16 years old) underwent proximal tibia oncologic intra-articular resection with wide margins. Primary diagnosis included giant cell tumor, osteosarcoma, chondrosarcoma and a failed osteoarticular allograft in 10, 4, 3 and 2 patients respectively. Tibial resection length was 10.4±3.4 cm in 18 knees. In one patient with chondrosarcoma the entire tibia was resected. Three patients received preoperative and postoperative chemotherapy, one only postoperative. Reconstruction was performed with an allograft-prosthesis composite implant and direct suture of the host patellar tendon to the allograft one. Fresh frozen allograft and modular Link prosthesis were used for reconstruction. Five to six weeks of knee immobilization in extension followed the operation. A transient peroneal nerve palsy was observed in three patients. Two patients with a stiff knee underwent an open release after less than one year from index surgery. One patient had a local recurrence from osteosarcoma and underwent an above knee amputation. No patient developed distant metastasis at follow-up. After 59±37 months none of the patients had implant revision for mechanical complications. One patient had 2-stage implant revision for deep infection. A minor allograft resorption with aseptic drain was observed in one patient who underwent surgical debridement. One other patient had a moderate allograft resorption. Knee flexion was 96±12 degrees. All the patients but two could reach complete knee extension and only two had a minor extensor lag (less than 15 degrees). In conclusion intrarticular tibia resection and allograft-prosthesis composite replacement ensures satisfactory oncologic and functional results at a mid-term follow-up

As for the number of patients who requires total knee arthroplasty (TKA), Asian-Pacific countries will be the most important market. However, due to the paucity of anthropometric data on the proximal tibia in this population, many prostheses designed for Caucasian knees have been introduced without specific modification.The aim of the current study was to analyze the geometry of the proximal tibia to design the optimum component for the Japanese population. Anthropometric data on the proximal tibia of 100 knees in 80 patients undergoing TKA was obtained. Briefly, anterior-posterior (AP) and medial-lateral (ML) lengths were measured with a combination of two different methods, namely on the computed tomography (CT) images obtained preoperatively and intraoperative direct measurement on tibial resection surface. Reproducible measurement was possible only when the intraoperative measurement was combined with the corresponding CT images while the direction of measurements being aligned to the epicondylar axis of the femur. It was shown that smaller components with an ML of around 60 mm were rarely required. Tibial component size variation should focus on an ML length of 65 to 75 mm because 76 of 100 knees (76 %) fell into this size range. When the subjects were confined to women, 70 of 77 knees (91%) were included in this size range. The intraoperative AP to ML ratio had a negative correlation with the ML length (r = −0.412, P < 0.0001) indicating that bigger knees were shallower in the AP direction. The size variation of currently popular pros-theses were not in accordance with the geometry of the tibial resection surface shown in this study. The results of this study applied to a cross-section of the Japanese population can be used by manufacturers to create a prosthesis suitable for most of the Asian-Pacific population

Introduction: Fresh autogenous cancellous bone graft is the material of choice in reconstruction and fusion procedures in foot and ankle surgery. There are many potential donor sites for graft harvest, all with recognised minor and major complications. The proximal tibia is one such potential site, and is particularly suited to foot and ankle surgery being within the operative field and under tourniquet control. Purpose: To assess pain, morbidity and ability to weight bear in a large group of patients undergoing foot and ankle surgery utilising cancellous bone graft from the proximal tibia. Method: A retrospective audit was undertaken of 148 procedures performed over a period of five years. Minimum follow-up was 3 months. Data were obtained from operation notes and patient interview. Results: Most patients had no pain (78%) or very mild pain (20%) at the site of graft harvest immediately following surgery. At review, 96% had no pain; 4% had very mild pain with certain activities such as kneeling. There were no major complications. 4 patients (2.7%) had persisting areas of parasthaesia at review, but none were troubled by it. One patient had a superficial wound problem that resolved. The ability to bear weight was dictated by the primary procedure. Usually this was from 2–3 weeks. There were no complications related to early weight bearing in this series. Conclusion: The proximal tibia is a suitable and safe site for bone graft harvest for foot and ankle surgery. There is no need for additional restriction in weight bearing following this procedure

Abstract. Objectives. This study aids the control of remodelling and strain response in bone; providing a quantified map of apparent modulus and strength in the proximal tibia in 3 anatomically relevant directions in terms of apparent density and factor groups. Methods. 7 fresh-frozen cadaveric specimens were quantified computed tomography (qCT) scanned, segmented and packed with 3 layers of 9mm side length cubic cores aligned to anatomical mechanical axes. Cores were removed with printed custom cutting and their densities found from qCT. Cores (n = 195) were quasi-statically compression tested. Modulus was estimated from a load cycle hysteresis loop, between 40% and 20% of yield stress. Sequential testing order in 3 orthogonal directions was randomised. Group differences were identified via an analysis of variance for the factors density, age, gender, testing order, subchondral depth, condyle and sub-meniscal location. Regression models were fit for significant factor sub-groups, predicting properties from density. Results. Axial modulus was 1.5 times greater than the two transverse directions (p<0.001), between which no difference was found. For all test directions, differences were quantified for density and modulus across all subchondral depths (p<0.001). 60% of transverse modulus variation was explained by density within subgroups for each subchondral depth. Medial axial modulus was 1.3 times greater than the lateral side (p = 0.011). Lateral axial modulus halved over a 25mm depth whilst remaining constant for the medial side. Density explained 75% of variation when grouped by subchondral depth and condyle. Yield strength was well predicted across all test directions, with density explaining 81% of axial strength variation and no differences over subchondral depth. Conclusions. The quantification of bone multiaxial modulus based on condyle and subchondral depth has been shown for the first time in a clinically viable protocol using conventional CT. Accounting for spatial variation improves upon literature property prediction models. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Introduction: ACL reconstruction with PTFE grafts enjoyed a brief period of popularity approximately a decade ago but early failures led to the technique being largely abandoned for primary reconstruction. We present a case where a patient presented several years after initial reconstruction because of an increase in pain. Case Report: A 43 year old man presented to the clinic because of an increase in knee symptoms without a specific history of trauma. He had previously undergone a PTFE reconstruction of his acl. X-rays at the time revealed a large, expanding cyst in his proximal tibia which was approximately 5x3x3cm. Management: In view of the increasing bone loss it was decided to manage this case surgically. After thorough debridement of the cavity in the proximal tibia morcellised bone was grafted into the defect on the tibial side. The femoral side of the graft was removed but no further treatment was required. Histology of the lesion revealed copious amounts of PTFE debris. Outcome: After 3 years of follow up the tibial graft has incorporated and radiologically the proximal tibia has consolidated well. Symptomatically the patient is improved and there have been no problems relating to instability. Conclusion: Autologous grafting of the proximal tibia is a useful technique in this unusual circumstance. With the increase in synthetic graft use on the continent it is possible that more similar cases will present

Aims: Severe proximal tibia fractures, which include intra- and extraarticular fractures with metaphyseal-diaphyseal dissociation, pose a difþcult treatment problem for the surgeon with signiþcant complication rates. The aim of this study is to report the experience with a series of consecutive severe proximal tibial fractures treated with hybrid external þxators. Methods: Between 1997 and 2001, we treated 118 cases of proximal tibia fractures of which 52 were treated with hybrid external þxation. Inclusion criteria for hybrid treatment was severe soft-tissue injury, intra-articular displacement, and unstable fracture patterns involvment. In addition to routine demographic data, objective data collected included healing, deformity, complications, and motion. Patient were also evaluated with an SF-36 12 months after healing. Results: All proximal tibial fractures healed without additional procedures. Most patients demonstrated healing by 16 weeks. Accuracy of redution was 0–1mm in 28 patients, 2–3 mm in 19 patients, and 4–5 mm in 4 patients and greater than 5 mm in one patient. Only 5 (10%) of the 52 patients had an angular malunion greater than 6û. One case had a loss of reduction. Four patients developed a mild varus deformity. Radiographic and clinical evidence of degenerative arthritis was seen in 12/52 (23%) patients 18 months after healing. The SF-36 proþlese were health state/rate, daily activity, work activity, emotional problems, pain. Conclusion: We found that hybrid external þxation is a good alternative method for treatment of meta- and/or epiphiseal fractures. The technique and post-op management we describe respects soft-tissue and bone biology and allows early articular mobilization

Introduction: Despite advances in limb-sparing techniques, the proximal tibia remains a difficult area in which to perform a wide resection of extensive bone tumors due to the intimate relationship to the nerves and blood vessels, inadequate soft-tissue coverage, and the need to reconstruct the extensor mechanism. The current long-term follow-up study, based on the experience with 55 patients who underwent proximal tibia endoprosthetic reconstruction emphasizes reconstruction of the extensor mechanism. Materials and Methods: Between 1980 and 1997, 55 patients underwent proximal tibia resection with endoprosthetic reconstruction. There were 34 males and 21 females whose age ranged from 8 to 56 years (median, 27 years. Diagnoses were: primary bone sarcomas – 48, benign aggressive lesions – 6, and failure of previous osteoarticular allograft reconstruction – 1. Intra-articular resection with en bloc removal of the tibial tuberosity was performed in all cases. Endoprosthetic reconstruction was performed with 39 modular, 16 custom-made prostheses. Reconstruction of the extensor mechanism included reattachment of the patellar tendon to the prosthesis with a Dacron tape and reinforcement with a gastrocnemius flap and bone grafting of the patellar tendon-prosthesis interface. Rehabilitation emphasized prolonged immobilization of knee joint in full extension. Results: All patients were followed for a minimum of 2 years (range 24–235 months, median – 75.5 months). Full extension to extension lag of 20° was achieved in 44 patients (78%), extension lag of 20° to 30° was found in 10 patients (19%), and extension lag of 40° was found in 1 patient (3%). Eight patients required an additional procedure which involved reinforcement of the patellar tendon with either combined quadriceps tendon and Goretex graft construct (seven patients) or simple plication of the tendon (one patient). Seven of these patients gained an extension lag of less than 20°. Overall, function was estimated to be good to excellent in 48 patients, fair in 6, and poor in one patient. Discussion: Extension lag of up to 20° is considered compatible with activities of daily living. Emphasis on reattachment of the patellar tendon to the prosthesis and its reinforcement with a gastrocnemius flap and bone graft achieved that goal in the majority of the patients. Secondary reinforcement of the patellar tendon is recommended for extension lag of more than 20°

Osteoarthritic (OA) changes to the bone morphology of the proximal tibia may exhibit load transfer patterns during total knee arthroplasty not predicted in models based on normal tibias. Prior work highlighted increased bone density in transverse sections of OA knees in the proximal-most 10mm tibial cancellous bone. Little is known about coronal plane differences, which could help inform load transfer from the tibial plateau to the tibial metaphysis. Therefore, we compared the cancellous bone density in OA and cadaveric (non-OA) subjects along a common coronal plane. This study included nine OA patients (five women, average age 59.1 ± 9.4 years) and 18 cadaver subjects (four women, average age 39.5 ± 14.4 years). Patients (eight with medial OA and one with lateral OA) received pre-operative CT scans as standard-of-care for a unicompartmental knee replacement. Cadavers were scanned at our institution and had no history of OA which was confirmed by gross inspection during dissection. 3D reconstructions of each proximal tibia were made and an ellipse was drawn on the medial and lateral plateau using a previously published method. A coronal section (Figure 1) to standardize the cohort was created using the medial ellipse center, lateral ellipse center, and the tibial shaft center 71.5mm from the tibial spine. On this section, profile lines were drawn from the medial and lateral ellipse centers, with data collected from the first subchondral bone pixel to a length of 20mm. The Hounsfield Units (HU) along each profile line was recorded for each tibia; a representative graphical distribution is shown in Figure 2. The Area Under the Curve (AUC) was calculated for the medial and lateral sides, which loosely described the stiffness profile through the region of interest. To determine differences between the medial and lateral subchondral bone density, the ratio AUC[medial] / AUC[lateral] was compared between the OA and cadaver cohorts using a two-sample t-test. Data from the sole lateral OA patient was mirror-imaged to be included in the OA cohort. The majority of the OA patients appeared to have higher subchondral bone density on the affected side. Figure 3 compares the medial and laterals sides of each group using the AUC ratio method described above. For the cadaver group the AUC was 1.2 +/− 0.22, with a median of 1.1 [0.9 1.6], smaller than the mean AUC for the OA group, which was 1.4 +/− 0.39, with a median of 1.6 [0.93 2.1]. The p-value was 0.06. The increased density observed in OA patients is consistent with asymmetric loading towards the affected plateau, resulting in localized remodeling of cancellous bone from the epiphysis to metaphysis. From the coronal plane, bone was often observed in OA patients bridging the medial plateau to the metaphyseal cortex. Although the cadaver subjects were normal from history and gross inspection, some subjects exhibited early bone density changes consistent with OA. Future work looks to review more OA scans, extend the work to the distal femur, and convert the HU values to bone elastic moduli for use in finite element modelling

Abstract. Approximately 20% of primary and revision Total Knee Arthroplasty (TKA) patients require multiple revisions, which are associated with poor survivorship, with worsening outcomes for subsequent revisions. For revision surgery, either endoprosthetic replacements or metaphyseal sleeves can be used for the repair, however, in cases of severe defects that are deemed “too severe” for reconstruction, endoprosthetic replacement of the affected area is recommended. However, endoprosthetic replacements have been associated with high complication rates (high incidence rates of prosthetic joint infection), while metaphyseal sleeves have a more acceptable complication profile and are therefore preferred. Despite this, no guidance exists as to the maximal limit of bone loss, which is acceptable for the use of metaphyseal sleeves to ensure sufficient axial and rotational stability. Therefore, this study assessed the effect of increasing bone loss on the primary stability of the metaphyseal sleeve in the proximal tibia to determine the maximal bone loss that retains axial and rotational stability comparable to a no defect control. Methods. to determine the pattern of bone loss and the average defect size that corresponds to the clinically defined defect sizes of small, medium and large defects, a series of pre-operative x-rays of patients with who underwent revision TKA were retrospectively analysed. Ten tibiae sawbones were used for the experiment. To prepare the bones, the joint surface was resected the typical resection depth required during a primary TKA (10mm). Each tibia was secured distally in a metal pot with perpendicular screws to ensure rotational and axial fixation to the testing machine. Based on X-ray findings, a fine guide wire was placed 5mm below the cut joint surface in the most medial region of the plateau. Core drills (15mm, 25mm and 35mm) corresponding to small, medium and large defects were passed over the guide wire allowing to act at the centre point, before the bone defect was created. The test was carried out on a control specimen with no defect, and subsequently on a Sawbone with a small, medium or large defect. Sleeves were inserted using the published operative technique, by trained individual using standard instruments supplied by the manufacturers. Standard axial pull-out (0 – 10mm) force and torque (0 – 30°) tests were carried out, recording the force (N) vs. displacement (mm) curves. Results. A circular defect pattern was identified across all defects, with the centre of the defect located 5mm below the medial tibial base plate, and as medial as possible. Unlike with large defects, small and medium sized defects reduced the pull-out force and torque at the bone-implant interface, however, these reductions were not statistically significant when compared to no bony defect. Conclusions. This experimental study demonstrated that up to 35mm radial defects may be an acceptable “critical limit” for bone loss below which metaphyseal sleeve use may still be appropriate. Further clinical assessment may help to confirm the findings of this experimental study. This study is the first in the literature to aim to quantify “critical bone loss” limit in the tibia for revision knee arthroplasty. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest