Aims. Adenosine, lidocaine, and Mg. 2+. (ALM) therapy exerts differential immuno-inflammatory responses in males and females early after anterior cruciate ligament (ACL) reconstruction (ACLR). Our aim was to investigate sex-specific effects of ALM therapy on joint tissue repair and recovery 28 days after surgery. Methods. Male (n = 21) and female (n = 21) adult Sprague-Dawley rats were randomly divided into ALM or Saline control treatment groups. Three days after ACL rupture, animals underwent ACLR. An ALM or saline intravenous infusion was commenced prior to skin incision, and continued for one hour. An intra-articular bolus of ALM or saline was also administered prior to skin closure. Animals were monitored to 28 days, and joint function, pain, inflammatory markers, histopathology, and tissue repair markers were assessed. Results. Despite comparable knee function, ALM-treated males had reduced systemic inflammation, synovial fluid angiogenic and pro-inflammatory mediators, synovitis, and fat pad fibrotic changes, compared to controls. Within the ACL graft, ALM-treated males had increased expression of tissue repair markers, decreased inflammation, increased collagen organization, and improved graft-bone healing. In contrast to males, females had no evidence of persistent systemic inflammation. Compared to controls, ALM-treated females had improved knee extension, gait biomechanics, and elevated synovial macrophage inflammatory protein-1 alpha (MIP-1α). Within the ACL graft, ALM-treated females had decreased inflammation, increased collagen organization, and improved graft-bone healing. In articular cartilage of ALM-treated animals, matrix metalloproteinase (MMP)-13 expression was blunted in males, while in females repair markers were increased. Conclusion. At 28 days, ALM therapy reduces inflammation, augments tissue repair patterns, and improves joint function in a sex-specific manner. The study supports transition to human safety trials. Cite this article: Bone Joint Res 2024;13(6):279–293

Aims. The aim of this study was to describe the prevalence and patterns of neuropathic pain over one year in a cohort of patients with chronic post-surgical pain at three months following total knee arthroplasty (TKA). Methods. Between 2016 and 2019, 363 patients with troublesome pain, defined as a score of ≤ 14 on the Oxford Knee Score pain subscale, three months after TKA from eight UK NHS hospitals, were recruited into the Support and Treatment After Replacement (STAR) clinical trial. Self-reported neuropathic pain and postoperative pain was assessed at three, nine, and 15 months after surgery using the painDETECT and Douleur Neuropathique 4 (DN4) questionnaires collected by postal survey. Results. Symptoms of neuropathic pain were common among patients reporting chronic pain at three months post-TKA, with half reporting neuropathic pain on painDETECT (191/363; 53%) and 74% (267/359) on DN4. Of those with neuropathic pain at three months, half continued to have symptoms over the next 12 months (148/262; 56%), one-quarter had improved (67/262; 26%), and for one-tenth their neuropathic symptoms fluctuated over time (24/262; 9%). However, a subgroup of participants reported new, late onset neuropathic symptoms (23/262; 9%). Prevalence of neuropathic symptoms was similar between the screening tools when the lower cut-off painDETECT score (≥ 13) was applied. Overall, mean neuropathic pain scores improved between three and 15 months after TKA. Conclusion. Neuropathic pain is common in patients with chronic pain at three months after TKA. Although neuropathic symptoms improved over time, up to half continued to report painful neuropathic symptoms at 15 months after TKA. Postoperative care should include screening, assessment, and treatment of neuropathic pain in patients with early chronic postoperative pain after TKA. Cite this article: Bone Joint J 2024;106-B(6):582–588

Aims. The diagnosis of periprosthetic joint infection (PJI) can be challenging as the symptoms are similar to other conditions, and the markers used for diagnosis have limited sensitivity and specificity. Recent research has suggested using blood cell ratios, such as platelet-to-volume ratio (PVR) and platelet-to-lymphocyte ratio (PLR), to improve diagnostic accuracy. The aim of the study was to further validate the effectiveness of PVR and PLR in diagnosing PJI. Methods. A retrospective review was conducted to assess the accuracy of different marker combinations for diagnosing chronic PJI. A total of 573 patients were included in the study, of which 124 knees and 122 hips had a diagnosis of chronic PJI. Complete blood count and synovial fluid analysis were collected. Recently published blood cell ratio cut-off points were applied to receiver operating characteristic curves for all markers and combinations. The area under the curve (AUC), sensitivity, specificity, and positive and negative predictive values were calculated. Results. The results of the analysis showed that the combination of ESR, CRP, synovial white blood cell count (Syn. WBC), and polymorphonuclear neutrophil percentage (PMN%) with PVR had the highest AUC of 0.99 for knees, with sensitivity of 97.73% and specificity of 100%. Similarly, for hips, this combination had an AUC of 0.98, sensitivity of 96.15%, and specificity of 100.00%. Conclusion. This study supports the use of PVR calculated from readily available complete blood counts, combined with established markers, to improve the accuracy in diagnosing chronic PJI in both total hip and knee arthroplasties. Cite this article: Bone Jt Open 2023;4(11):881–888

Aims. Implantation of ultra-purified alginate (UPAL) gel is safe and effective in animal osteochondral defect models. This study aimed to examine the applicability of UPAL gel implantation to acellular therapy in humans with cartilage injury. Methods. A total of 12 patients (12 knees) with symptomatic, post-traumatic, full-thickness cartilage lesions (1.0 to 4.0 cm. 2. ) were included in this study. UPAL gel was implanted into chondral defects after performing bone marrow stimulation technique, and assessed for up to three years postoperatively. The primary outcomes were the feasibility and safety of the procedure. The secondary outcomes were self-assessed clinical scores, arthroscopic scores, tissue biopsies, and MRI-based estimations. Results. No obvious adverse events related to UPAL gel implantation were observed. Self-assessed clinical scores, including pain, symptoms, activities of daily living, sports activity, and quality of life, were improved significantly at three years after surgery. Defect filling was confirmed using second-look arthroscopy at 72 weeks. Significantly improved MRI scores were observed from 12 to 144 weeks postoperatively. Histological examination of biopsy specimens obtained at 72 weeks after implantation revealed an extracellular matrix rich in glycosaminoglycan and type II collagen in the reparative tissue. Histological assessment yielded a mean overall International Cartilage Regeneration & Joint Preservation Society II score of 69.1 points (SD 10.4; 50 to 80). Conclusion. This study provides evidence supporting the safety of acellular UPAL gel implantation in facilitating cartilage repair. Despite being a single-arm study, it demonstrated the efficacy of UPAL gel implantation, suggesting it is an easy-to-use, one-step method of cartilage tissue repair circumventing the need to harvest donor cells. Cite this article: Bone Joint J 2023;105-B(8):880–887

Aims. Distal femoral resection in conventional total knee arthroplasty (TKA) utilizes an intramedullary guide to determine coronal alignment, commonly planned for 5° of valgus. However, a standard 5° resection angle may contribute to malalignment in patients with variability in the femoral anatomical and mechanical axis angle. The purpose of the study was to leverage deep learning (DL) to measure the femoral mechanical-anatomical axis angle (FMAA) in a heterogeneous cohort. Methods. Patients with full-limb radiographs from the Osteoarthritis Initiative were included. A DL workflow was created to measure the FMAA and validated against human measurements. To reflect potential intramedullary guide placement during manual TKA, two different FMAAs were calculated either using a line approximating the entire diaphyseal shaft, and a line connecting the apex of the femoral intercondylar sulcus to the centre of the diaphysis. The proportion of FMAAs outside a range of 5.0° (SD 2.0°) was calculated for both definitions, and FMAA was compared using univariate analyses across sex, BMI, knee alignment, and femur length. Results. The algorithm measured 1,078 radiographs at a rate of 12.6 s/image (2,156 unique measurements in 3.8 hours). There was no significant difference or bias between reader and algorithm measurements for the FMAA (p = 0.130 to 0.563). The FMAA was 6.3° (SD 1.0°; 25% outside range of 5.0° (SD 2.0°)) using definition one and 4.6° (SD 1.3°; 13% outside range of 5.0° (SD 2.0°)) using definition two. Differences between males and females were observed using definition two (males more valgus; p < 0.001). Conclusion. We developed a rapid and accurate DL tool to quantify the FMAA. Considerable variation with different measurement approaches for the FMAA supports that patient-specific anatomy and surgeon-dependent technique must be accounted for when correcting for the FMAA using an intramedullary guide. The angle between the mechanical and anatomical axes of the femur fell outside the range of 5.0° (SD 2.0°) for nearly a quarter of patients. Cite this article: Bone Jt Open 2024;5(2):101–108

Aims. The aim of this study was to determine whether obesity had a detrimental effect on the long-term performance and survival of medial unicompartmental knee arthroplasties (UKAs). Methods. This study reviewed prospectively collected functional outcome scores and revision rates of all medial UKA patients with recorded BMI performed in Christchurch, New Zealand, from January 2011 to September 2021. Patient-reported outcome measures (PROMs) were the primary outcome of this study, with all-cause revision rate analyzed as a secondary outcome. PROMs were taken preoperatively, at six months, one year, five years, and ten years postoperatively. There were 873 patients who had functional scores recorded at five years and 164 patients had scores recorded at ten years. Further sub-group analysis was performed based on the patient’s BMI. Revision data were available through the New Zealand Joint Registry for 2,323 UKAs performed during this time period. Results. Obese patients (BMI > 30 kg/m. 2. ) were 3.1 years younger than non-obese patients (BMI < 30 kg/m. 2. ) at the time of surgery (mean age of obese patients 65.5 years (SD 9.7) and mean age of non-obese patients 68.6 years (SD 10.1)). Preoperatively, obese patients tended to have significantly lower functional scores than non-obese patients, which continued at five and ten years postoperatively. At these timepoints, obese patients had significantly lower scores for most PROMs measured compared to non-obese patients. However, there was no significant difference in the improvement of any of these scores after surgery between obese and non-obese patients. There was no significant difference in revision rates between obese and non-obese patients at any time. All-cause revision rate for obese patients was 0.73 per 100 observed component years compared to 0.67 in non-obese patients at ten years. There was also no significant difference in the aseptic loosening rate between groups. Conclusion. Our study supports the use of UKAs in obese patients, with similar benefit and survival compared to non-obese patients at ten years

Aims. This study examined windswept deformity (WSD) of the knee, comparing prevalence and contributing factors in healthy and osteoarthritic (OA) cohorts. Methods. A case-control radiological study was undertaken comparing 500 healthy knees (250 adults) with a consecutive sample of 710 OA knees (355 adults) undergoing bilateral total knee arthroplasty. The mechanical hip-knee-ankle angle (mHKA), medial proximal tibial angle (MPTA), and lateral distal femoral angle (LDFA) were determined for each knee, and the arithmetic hip-knee-ankle angle (aHKA), joint line obliquity, and Coronal Plane Alignment of the Knee (CPAK) types were calculated. WSD was defined as a varus mHKA of < -2° in one limb and a valgus mHKA of > 2° in the contralateral limb. The primary outcome was the proportional difference in WSD prevalence between healthy and OA groups. Secondary outcomes were the proportional difference in WSD prevalence between constitutional varus and valgus CPAK types, and to explore associations between predefined variables and WSD within the OA group. Results. WSD was more prevalent in the OA group compared to the healthy group (7.9% vs 0.4%; p < 0.001, relative risk (RR) 19.8). There was a significant difference in means and variance between the mHKA of the healthy and OA groups (mean -1.3° (SD 2.3°) vs mean -3.8°(SD 6.6°) respectively; p < 0.001). No significant differences existed in MPTA and LDFA between the groups, with a minimal difference in aHKA (mean -0.9° healthy vs -0.5° OA; p < 0.001). Backwards logistic regression identified meniscectomy, rheumatoid arthritis, and osteotomy as predictors of WSD (odds ratio (OR) 4.1 (95% CI 1.7 to 10.0), p = 0.002; OR 11.9 (95% CI 1.3 to 89.3); p = 0.016; OR 41.6 (95% CI 5.4 to 432.9), p ≤ 0.001, respectively). Conclusion. This study found a 20-fold greater prevalence of WSD in OA populations. The development of WSD is associated with meniscectomy, rheumatoid arthritis, and osteotomy. These findings support WSD being mostly an acquired condition following skeletal maturity. Cite this article: Bone Jt Open 2024;5(10):879–885

Aims. Periprosthetic joint infection (PJI) is a devastating complication following total knee arthroplasty (TKA). Two-stage revision has traditionally been considered the gold standard of treatment for established infection, but increasing evidence is emerging in support of one-stage exchange for selected patients. The objective of this study was to determine the outcomes of single-stage revision TKA for PJI, with mid-term follow-up. Methods. A total of 84 patients, with a mean age of 68 years (36 to 92), underwent single-stage revision TKA for confirmed PJI at a single institution between 2006 and 2016. In all, 37 patients (44%) were treated for an infected primary TKA, while the majority presented with infected revisions: 31 had undergone one previous revision (36.9%) and 16 had multiple prior revisions (19.1%). Contraindications to single-stage exchange included systemic sepsis, extensive bone or soft-tissue loss, extensor mechanism failure, or if primary wound closure was unlikely to be achievable. Patients were not excluded for culture-negative PJI or the presence of a sinus. Results. Overall, 76 patients (90.5%) were infection-free at a mean follow-up of seven years, with eight reinfections (9.5%). Culture-negative PJI was not associated with a higher reinfection rate (p = 0.343). However, there was a significantly higher rate of recurrence in patients with polymicrobial infections (p = 0.003). The mean Oxford Knee Score (OKS) improved from 18.7 (SD 8.7) preoperatively to 33.8 (SD 9.7) at six months postoperatively (p < 0.001). The Kaplan-Meier implant survival rate for all causes of reoperation, including reinfection and aseptic failure, was 95.2% at one year (95% confidence interval (CI) 87.7 to 98.2), 83.5% at five years (95% CI 73.2 to 90.3), and 78.9% at 12 years (95% CI 66.8 to 87.2). Conclusion. One-stage exchange, using a strict debridement protocol and multidisciplinary input, is an effective treatment option for the infected TKA. This is the largest single-surgeon series of consecutive cases reported to date, with broad inclusion criteria. Cite this article: Bone Jt Open 2021;2(5):305–313

Aims

The rate of day-case total knee arthroplasty (TKA) in the UK is currently approximately 0.5%. Reducing length of stay allows orthopaedic providers to improve efficiency, increase operative throughput, and tackle the rising demand for joint arthroplasty surgery and the COVID-19-related backlog. Here, we report safe delivery of day-case TKA in an NHS trust via inpatient wards with no additional resources.

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To identify variables independently associated with same-day discharge (SDD) of patients following revision total knee arthroplasty (rTKA) and to develop machine learning algorithms to predict suitable candidates for outpatient rTKA.

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This study aimed to explore the biological and clinical importance of dysregulated key genes in osteoarthritis (OA) patients at the cartilage level to find potential biomarkers and targets for diagnosing and treating OA.

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Aseptic loosening is the most common cause of failure following cemented total knee arthroplasty (TKA), and has been linked to poor cementation technique. We aimed to develop a consensus on the optimal technique for component cementation in TKA.

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With up to 40% of patients having patellofemoral joint osteoarthritis (PFJ OA), the two arthroplasty options are to replace solely the patellofemoral joint via patellofemoral arthroplasty (PFA), or the entire knee via total knee arthroplasty (TKA). The aim of this study was to assess postoperative success of second-generation PFAs compared to TKAs for patients treated for PFJ OA using patient-reported outcome measures (PROMs) and domains deemed important by patients following a patient and public involvement meeting.

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The metabolic equivalent of task (MET) score examines patient performance in relation to energy expenditure before and after knee arthroplasty. This study assesses its use in a knee arthroplasty population in comparison with the widely used Oxford Knee Score (OKS) and EuroQol five-dimension index (EQ-5D), which are reported to be limited by ceiling effects.

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To explore the efficacy of extracorporeal shockwave therapy (ESWT) in the treatment of osteochondral defect (OCD), and its effects on the levels of transforming growth factor (TGF)-β, bone morphogenetic protein (BMP)-2, -3, -4, -5, and -7 in terms of cartilage and bone regeneration.

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To map the Oxford Knee Score (OKS) and High Activity Arthroplasty Score (HAAS) items to a common scale, and to investigate the psychometric properties of this new scale for the measurement of knee health.

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This Delphi study assessed the challenges of diagnosing soft-tissue knee injuries (STKIs) in acute settings among orthopaedic healthcare stakeholders.

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Distal femoral osteotomies (DFOs) are commonly used for the correction of valgus deformities and lateral compartment osteoarthritis. However, the impact of a DFO on subsequent total knee arthroplasty (TKA) function remains a subject of debate. Therefore, the purpose of this study was to determine the effect of a unilateral DFO on subsequent TKA function in patients with bilateral TKAs, using the contralateral knee as a self-matched control group.

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We aimed to assess the reliability and validity of OpenPose, a posture estimation algorithm, for measurement of knee range of motion after total knee arthroplasty (TKA), in comparison to radiography and goniometry.

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While residual fixed flexion deformity (FFD) in unicompartmental knee arthroplasty (UKA) has been associated with worse functional outcomes, limited evidence exists regarding FFD changes. The objective of this study was to quantify FFD changes in patients with medial unicompartmental knee arthritis undergoing UKA, and investigate any correlation with clinical outcomes.