Aims

Current guidelines consider analyses of joint aspirates, including leucocyte cell count (LC) and polymorphonuclear percentage (PMN%) as a diagnostic mainstay of periprosthetic joint infection (PJI). It is unclear if these parameters are subject to a certain degree of variability over time. Therefore, the aim of this study was to evaluate the variation of LC and PMN% in patients with aseptic revision total knee arthroplasty (TKA).

Aims

To explore the clinical relevance of joint space width (JSW) narrowing on standardized-flexion (SF) radiographs in the assessment of cartilage degeneration in specific subregions seen on MRI sequences in knee osteoarthritis (OA) with neutral, valgus, and varus alignments, and potential planning of partial knee arthroplasty.

Introduction

The medial patellofemoral ligament (MPFL) is the main stabilizer of the patella and therefore mostly reconstructed in the surgical correction of patellofemoral dislocation. Various biomechanical and clinical studies have been conducted on MPFL reconstruction, while the patellofemoral contact pressure (PFCP) which is indicated as one of the predictors of retropatellar osteoarthritis was neglected. Therefore, the aim of this study was to investigate how different MPFL reconstruction approaches affect PFCP.

Introduction

With processing age, meniscus degeneration occurs which is often associated with osteoarthritis. Existing data about the influence of degeneration on the biomechanical properties of the meniscus are still contradictory, or completely unknown regarding the hydraulic permeability. Thus, the aim of this study was to characterise the biomechanical properties and structural composition of the meniscal tissue depending on its degree of degeneration.

Cartilage injury is generally associated with cytokine release and accumulation of reactive oxygen species. These mediators trigger pathologic behaviour of the surviving chondrocytes, which respond by excessive expression of catabolic enzymes, such as matrix metalloproteinase 13 (MMP-13), reduced synthesis of type II collagen (COL2A1) and apoptosis. In the long run, these pathologic conditions can cause a posttraumatic osteoarthritis. With the objective to attenuate the progressive degradation of the extracellular matrix and, what is more, promote chondroanabolic processes, a multidirectional treatment of trauma-induced pathogenesis was tested for the first time. Therefore, we evaluated the combinations of one anabolic growth factor (IGF-1, FGF18 or BMP7) with the antioxidant N-acetyl cysteine (NAC) in a human ex vivo cartilage trauma model and compared the findings with the corresponding monotherapy. Human cartilage tissue was obtained with informed consent from donors undergoing knee joint replacement (n=24). Only macroscopically intact tissue was used to prepare explants. Cartilage explants were subjected to a blunt impact (0.59 J) by a drop-tower and treated by IGF-1 [100 ng/mL], FGF18 [200 ng/mL] or BMP7 [100 ng/mL] and/or NAC [2 mM] for 7 days. Following parameters were analysed: cell viability (live/dead staining), gene expression (qRT-PCR) as well as biosynthesis (ELISA) of type II collagen and MMP-13. For statistical analysisKruskal-Wallis or One-way ANOVA was used. All data were collected in the orthopedic research laboratory of the University of Ulm, Germany.

Trauma-induced cell death was completely prevented by NAC treatment and FGF18 or BMP7 to a large extent, respectively (p<0.0001). IGF-1 exhibited only poor cell protection. Combination of NAC and FGF18 or BMP7 did not result in enhanced effectiveness; however, IGF-1 significantly reduced NAC-mediated cell protection. While IGF-1 or BMP7 induced collagen type II gene expression (p=0.0069 and p<0.0001, respectively) and its biosynthesis (p<0.0001 and p=0.0131, respectively), NAC or FGF18 caused significant suppression of this matrix component (each p<0.001). Although COL2A1 mRNA was significantly increased by NAC plus IGF-1 (p<0.0001), biosynthesis of collagen type II was generally abolished after multidirectional treatment. Except for IGF-1, all tested therapeutics exhibited chondroprotective qualities, as demonstrated by attenuated MMP-13 expression and breakdown of type II collagen. In combination with IGF-1, NAC-mediated chondroprotection was reduced.

Overall, both chondroanabolic and antioxidative therapy had individual advantages. Since adverse interactions were found by simultaneous application of the therapeutics, a sequential approach might improve the efficacy. In support of this strategy current experiments showed that though cell and chondroprotective effects of NAC were maintained after withdrawal of the antioxidant, type II collagen expression recovered by time.

Background

Femoroacetabular impingement due to a reduced femoral head-neck-offset or excessive acetabular coverage will lead to early cartilage lesions of the hip joint. The purpose of the present study was to analyze the relationship between the extent of bony deformity and the presence and extent of cartilage lesions in femoroacetabular impingement.

Reduction therapy in developmental dysplasia of the hip (DDH) is initialized in the newborn period. Harness treatment is continued until normal ultrasound-values are reached. Above the age of one year the assessment of DDH relies mainly on interpretation of plain radiographs of the pelvis. In order to rule out residual dysplasia after ultrasound controlled treatment radiological control is advised to the time children start walking. The purpose of this study is to evaluate the early radiological outcome after ultrasound controlled treatment of DDH and to examine whether there is a correlation between the initial severitiy of DDH, measured by ultrasound, and the severity of residual DDH on the radiograph at the time of the first follow-up.

A. p. pelvic radiographs of 90 children (72 girls, 18 boys, 180 hips) with DDH (29 unilateral, 61 bilateral) were reviewed retrospectively. To the beginning of the ultrasound surveilled therapy (mean age 7,2 weeks) the morphologic findings were staged according to the Graf classification. Ultrasound surveilled abduction treatment was continued until normal ultrasound findings were reached. To the time children started walking (mean age 14,8 months) an a. p. radiograph of the pelvis was performed. The acetabular index (AI) was measured and classified according to the normal values of the hip joint described by Tönnis. The initial ultrasound findings expressed by the Graf classification were compared with the AI in the radiographic follow-up and Tönnis’ normal values.

To simplify matters the 180 Graf-classified hips were distributed into 4 categories: Graf Ia/b=category 1, Graf IIa-D=category 2, Graf IIIa/b=category 3, Graf IV=category 4. The initially normal contralateral hips in ultrasound (n=29, category 1) presented in 37,9% a normal AI, in 41,4% with a mild dysplasia (between 1SD and 2SD) and in 20,7% with a severe dysplasia (beyond 2SD). The Graf type IIa-D hips (n=81, category 2) presented in 37% a normal AI, 32,1% showed a mild dysplasia and 30,9% a severe dysplasia. The Graf type III a/b hips (n=60, category 3) showed 35%, 30% and 35%, Graf type IV hips (n=10, category 4) 60%, 30% and 10%, respectively.

The mean AI in all four categories differed only marginally.

In our setting of patients different conclusions can be drawn:

Even after successful ultrasound guided therapy with a sonographically normal hip at the time bracing is finished there is a risk for residual dysplasia. Therefore radiological follow-up of every once treated hip is necessary.

We report on a patient with an unusual pulmonary infection after resection of a high-grade osteosarcoma. In March 2007 a 30-year old female with pain and swelling of the left proximal humerus was submitted to the orthopaedic department. Rx and CT revealed a tumour with destruction and invasion of the surrounding soft tissue.

Incision biopsy led to the diagnosis of osteoblastic osteosarcoma. She was enrolled into the EURAMOS protocol and received neoadjuvant chemotherapy. In July 2007 an extra-articular resection of the proximal humerus with modular endoprosthetic replacement was performed. The sarcoma had responded well to chemotherapy (regression grade 3 according to Salzer-Kunts-chik). Surprisingly, the resection specimen demonstrated a “skip lesion” of vital sarcoma in the resection line not been detected by preoperative PET or MRT. After consultation of the German study group she was stratified into the standard risk group.

12 months later a control CT revealed multiple foci in both lungs, which were highly suspicious for pulmonary metastases. All clinical parameters were normal. A lung biopsy was performed by thoracotomy and a granulomatous infection was diagnosed, which was suspicious for tuberculosis. Extended microbiological investigations by culture and PCR analysis revealed an infection by Myco-bacterium Xenopi, which is a rare form of an atypical mycobacteriosis. Since then she is treated accordingly, however the infection has progressed and involvement of the liver has been diagnosed by cutting needle biopsy.

Introduction: Whereas in traumatic avascular necrosis of the femoral head (ANFH) loss of the femoral head’s blood supply is due to a mechanical event, in non-traumatic AFNH it is the result of a wide variety of etiologies (e.g. alcoholism, hypercortisonism, etc.), which have in common that they lead to an intravascular complication with subsequent malperfusion of the femoral head. Additionally, for part of non-traumatic ANFH no causative factors are known, why they are called idiopathic. A mechanical cause for nontraumatic ANFH – as e.g. a repetitive trauma of the femoral head supplying deep branch of the medial femoral circumflex artery and its terminal branches by abutment of the femur against the acetabulum as in femoroacetabular impingement (FAI) – has not been discussed so far.

Methods: The anteroposterior and lateral radiographs of 118 hips in 77 patients, who were operated in our institution between January 1995 and December 2005 because of nontraumatic ANFH, were evaluated with respect to the configuration of the head-neck junction.

In a qualitative analysis the head-neck contour of all femora was assigned to one of the following four groups: regular waisting, mildly reduced waisting, reduced to distinctly reduced waisting or completely lacking waisting.

Results: In this retrospective analysis, for 44.1% of the hip joints hypercortisonism, for 40.7% alcoholism, for 12.7% hypercholesterinemia and for 11.0% no risk factors were found documented in the patients’ files. In AP and lateral radiographs a regular waisting was found in 60.2% and 9.3%, a mildly reduced waisting in 32.2% and 37.3%, a reduced waisting or distinctly reduced waisting in 7.6% and 35.6%, and a completely lacking waisting in 0% and 16.9%, respectively, and the mean angle alpha was 63° ± 18° and 67° ± 14°, respectively. On average, the (frontally projected) CCD angle was 133° ± 6°, the LCE angle 30° ± 7° and the acetabular index of the weightbearing zone 4° ± 5°.

Conclusion: Nötzli et al. found an angle alpha of 42° ± 2° for healthy individuals. A markedly increased angle alpha in both radiographic planes of the 118 investigated hips with nontraumatic ANFH was found, demonstrating a reduced shape of their head-neck junction in the anterior and lateral aspect. Together with the fact that no gross pathological deviations for the orientation of the femoral neck and the acetabulum were found, this may hint at cam-type FAI to occur in this hips and thus potentially at a mechanical (co-) factor in developing non-traumatic ANFH.

The non-invasive diagnosis of musculoskeletal infections remains a challenge. Recent studies have indicated that fluorine-18 fluorodeoxyglucosepositron emission tomography (FDG-PET) is a highly accurate imaging technique in selected patient groups with infected total hip replacement. The present study analyses the diagnostic accuracy in a consecutive series of patients with suspected musculoskeletal infections.

METHODS: 163 consecutive patients with suspected periprosthetic infections (40 THR, 46 TKR), discitis (22) or a suspected infection involving the peripheral skeleton (55) were studied with FDG-PET. In this retrospective study two independent nuclear medicine physicians interpreted the images solely based on the information provide at the time of investigation. The final diagnosis was based on histopathological studies or microbiological culture or on clinical findings after at least twelve months of follow-up.

Results: Based on the final composite assessment, 21/40 patients with THR, 15/46 with TKR, 22/55 with suspected infection in the peripheral skeleton and 10/22 with suspected discitis had infection. FDG-PET identified correctly 68/76 infections (sensitivity 89.5%) and demonstrated a negative predictive value of 81/87 (specificity 93.1%). FDG-PET was of different diagnostic value at different sites with sensitivity and specificity for suspected infections of THR (100/81.3), TKR (81.8/85.7) infections of the peripheral skeleton (90.9/100) and discitis (100/100).

DISCUSSION AND Conclusions: FDG-PET is highly accurate for the evaluation of musculoskeletal infections. While it correctly identified all patients with suspected discitis, it seems also be reliable to rule out infected THR. However, the specificity in suspected infections of THR and TKR is lower due to granulomatous tissue caused by wear-induced polyethylene particles in aseptic loosening.

Introduction: There is rather broad consent that mildly slipped capital femoral epiphyses (SCFE) should be treated by in situ fixation with wires or dynamic screws. There is recent evidence, however, that even mild slips lead to early damage of the acetabular labrum and cartilage by abutment of a prominent femoral metaphysis. It is therefore proposed that treatment of mildly slipped capital femoral epiphyses should not only prevent further slipping of the epiphysis, but also address potential femoro-acetabular impingement (FAI) by restoring the anatomy of the proximal femur. To find proof for this newly proposed therapeutical approach, we reviewed all patients treated in our department ten to twenty years ago for unilateral slipped capital femoral epiphysis by in situ fixation without restoration of the anatomy of the proximal femur.

Methods: From forty-four patients treated between October 1984 and December 1995, twenty-eight could be contacted and eighteen reviewed. Development of FAI was documented by clinical examination (range of motion, “impingement provocation test”) and radiological evaluation (AP radiographs of the pelvis and lateral cross-table radiographs of both hips). Statistical analysis was performed with paired t test and Wilcoxon matched-pairs signed-ranks test in case of numerical data, and Fisher’s Exact Test and Chi-squared Test for Independence in case of ordinal data. The level of significance was set at p < 0.05.

Results: Comparing involved to non-involved hips, mean internal rotation and abduction differed significantly (15° ± 7.9° vs. 21° ± 7.9° (p < 0.01) and 37° ± 7.7° vs. 42° ± 6.7° (p < 0.01), respectively), but the “impingement provocation test” was found positive in only four vs. six hips (p = 0.71). Radiological examination showed significantly difference with respect to waisting of the femoral neck (p < 0.01) and bony appositions at the femoral head neck junction (p < 0.01). No regular waisting was found in all involved hips, whereas it was present in nine non-involved hips. A distinctly reduced or absent waisting was seen in twelve of the involved hips but in only four of the non-involved hips. Bony appositions were found in fourteen of the involved hips, but in only four of the non-involved hips. Furthermore the angle α according to Nötzli et al. (2002) showed a significant difference in its mean on AP radiographs (84° ± 10° vs. 60° ± 15°, p < 0.01), not so, however, in lateral cross-table radiographs (50° ± 8° vs. 48° ± 11°, p = 0.3).

Conclusion: From a clinical point of view, in situ fixation may be sufficient in treating mildly SCFE, whereas radiological data suggest that restoration of the anatomy of the head-neck junction of the proximal femur might be sensible to prevent or delay FAI and thus development of osteoarthritis of the respective hip joint.

Conventional treatment of mild slipped capital femoral epiphysis consists of fixation in situ with wires or screws. Recent contributions to the literature suggest that even a mild slip may lead to early damage of the acetabular labrum and adjacent cartilage by abutment of a prominent femoral metaphysis. It has been suggested that the appropriate treatment in mild slipped capital femoral epiphysis should not only prevent further slipping of the epiphysis, but also address potential femoroacetabular impingement by restoring the anatomy of the proximal femur.

Between October 1984 and December 1995 we treated 16 patients for unilateral mild slipped capital femoral epiphysis by fixation in situ with Kirschner wires. In this study we have reviewed these patients for clinical and radiological evidence of femoroacetabular impingement. There was little clinical indication of impingement but radiological evaluation assessing the femoral head-neck ratio and measuring the Nötzli α angle on the anteroposterior and cross-table radiographs showed significant alterations in the proximal femur. None of the affected hips had a normal head-neck ratio and the mean α angle was 86° (55° to 99°) and 55° (40° to 94°) on the anteroposterior and lateral cross-table radiographs, respectively.

While our clinical data favours conventional treatment, our radiological findings are in support of restoring the anatomy of the proximal femur to avoid or delay the development of femoroacetabular impingement following mild slipped capital femoral epiphysis.

The current concepts of proximal femoral fixation in hip arthroplasty can be divided into three groups: the surface replacement concept, the femoral neck prostheses, and the short stems prostheses.

Between 1999–2004 more than 500 short stems prostheses (Mayoä) were implanted at the Orthopaedic department of the Martin-Luther-University, Halle, Germany.

To investigate the early functional results, a prospective randomized study was performed comparing 40 cementless short stem prostheses (Mayoä 1) with 40 cementless anatomical standard stem prostheses (ABGä 2) implanted in patients with unilateral hip osteoarthritis.

Age, gender, diagnoses, and body mass index showed no significant difference between both groups. In all patients, an uncemented acetabular press-fit cup was used. The implantations were performed by 4 orthopaedic consultants. A standardized anterolateral approach to the hip was used in all cases. In the short stem group, the femoral neck was preserved to achieve a multi-point fixation of the double-tapered stem in the intertrochanteric region.

The patients were followed clinically and radiographically at 3, 6, and 12 months postoperatively. Differences between both groups were tested using Student’s t-test. No specific complications occurred neither during surgery nor during the follow-up (FU). No patient was lost for FU. The radiograhic FU showed a correct implant position in all cases.

Concerning the Harris hip score (HHS), a statistically significant difference (< 0.01) was found at 3 months: the HHS for the short stem group averaged 93.87 points (range, 60–100 points), for the ABG group 87.02 points (range, 60–100 points). Preoperatively, at 6, and at 12 months, no statistically significant difference could be found between both groups.

In this study, patients having a short stem prosthesis returned faster to work and normal daily activities. We attribute this to the femoral neck approach without involvement of the greater trochanter and the abductor muscles. With its good functional results and its bone-saving concept, the short stem is an attractive design particularly for young patients.