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Objectives: Baker's cysts are not uncommon in patients eligible for total knee arthroplasty (TKA). There is a paucity of medium-term studies that assess the natural course of Baker's cyst following TKA. In this study, we report the one and five year outcome of patients to elucidate the state[for full text, please go to the a.m. URL], Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2019)

Mechanical axis of the lower limb assessed in standing long-leg radiographs was demonstrated to change within the first three postoperative months after total knee arthroplasty (TKA). The underlying mechanism including the influence of limb loading for the change in mechanical axis alignment after TKA has not been evaluated so far. Mechanical axis of the lower limb and limb loading were evaluated in 115 patients 10 days and 12 weeks after TKA. Mechanical axis was measured in standing long-leg radiographs while limb loading was simultaneously assessed using a scale. Absolute and relative limb loading with their correlation to the mechanical axis were calculated. Mechanical axis in patients with postoperative complete extension (n = 100) changed from an initial -0.82° ± 1.9° valgus alignment to a varus axis of +0.6° ± 1.5 (p < 0.01). This change in alignment was accompanied by an increased limb loading from 89.9% 10.7% to 93.0% 7.0% (p < 0.01). The mechanical axis highly/significantly correlated with relative limb loading in both measurements (r = 0.804, p < 0.001 respectively r = 0.562, p < 0.001). These alterations and distinctions were much more pronounced in patients with postoperative incomplete extension. Mechanical axis of the leg significantly changes while limb loading increases within the first three postoperative months after TKA. The postoperative alignment highly correlates with the loading of the lower limb. Therefore, the actual mechanical axis can only be assessed at physiological limb loading in long-leg radiographs at complete extension with full weight bearing.

Aims and Objectives: Baker’s cysts are common in knees with degenerative changes. Common opinion is that most them vanish after treatment of the intraarticular knee disorder. The present study aimed to evaluate the fate of Baker’s cyst and its associated symptoms after TKA. Materials and Methods: In this prospective study, 105 patients with a MRI verified Baker’s cyst, primary OA and an appointment for TKA were included. Three patients were lost to follow-up (two died and one septic TKA removal). Mean age was 70.1 ± 7 years. Ultrasound was performed to evaluate the existing and the gross size of the cyst was performed before and one year (mean 12.3 ± 1.1 months) after TKA. Additionally, Baker’s cyst associated symptoms were recorded Results: After one year, Baker’s cysts were still detected in 85.3% of the patients (n = 87). There was a significant reduction in Baker’s cyst associated symptoms from before (70.6%) to after surgery (31.4%; p < 0.0001). No patients developed new Baker’s cyst associated symptoms. However, out of the 72 patients that reported preoperatively about Baker’s cyst associated symptoms, one year after surgery 44.4% (n = 32) of the patients still complained about Baker’s cyst associated symptoms. The size of Baker’s cysts decreased significantly from pre- (mean 1447 mm2) to postoperative (969 mm2) ultrasound assessment (p < 0.0001). Conclusion: Baker’s cysts vanished only in a small amount of patients (15%) one year after TKA. Nevertheless in this in general considered successful surgery, in close to half of the patients (44.4%) with preoperative Baker’s cyst associated symptoms, these symptoms did not vanish until one year after TKA. Thus, it might be worthwhile to evaluate its treatment options and include them in future treatment plans.

A bi-cruciate stabilized (BCS) guided-motion total knee arthroplasty (TKA) design was introduced to improve knee kinematics by more closely approximating those of a normal knee. Previous studies have shown a high incidence of complications with this implant type, which led to recent modifications of the design by the manufacturer. The current study was undertaken to assess whether the use of a guided-motion knee system with an extension-first surgical technique is associated with a similar rate of short-term adverse outcome as reported in literature. The secondary aim was to assess if there were any differences between the original and modified implant designs. This retrospective study enrolled 204 consecutive patients (204 knees) undergoing TKA for osteoarthritis of the knee, with the first 154 receiving cemented Journey BCS I implants and the remaining 51 receiving cemented Journey BCS II implants when these became available. At follow-up, patients were tested for the presence of iliotibial friction syndrome (ITB-F) and midflexion instability. Knee score and function score were taken preoperatively, at one year, and at final follow-up. Outcome data between the two implant types were compared using the Mann-Whitney test. No patients were lost to follow-up. Mean follow-up time for the cohort was 24.5 ± 7.8 months (range, 12 - 36 months). There were no cases of stiffness (flexion < 90°). Incidence of ITB-F syndrome was considered low: three (2.0%) knees in the BCS I group and two (3.9%) in the BCS II group (p = 0.367). Five (2.5%) knees presented with mild instability in midflexion, three (2.0%) in the BCS I group and two (3.9%) in the BCS II group (p = 0.367). One patient with a BCS I implant required reoperation for aseptic loosening 23 months postoperatively. At one-year follow-up, there were no significant differences in range of motion, knee score, or function score. When used in combination with an extension-first surgical technique, good early functional results with an acceptable rate of complications were obtained with both the original and the updated Journey BCS knee implant. Long-term follow-up studies are needed to confirm our findings.

Aims and Objectives: The use of patient-specific instruments (PSI) in total knee arthroplasty (TKA) has seen growing interest over the past years. A potential disadvantage of PSI is that functional implant alignment is not applicable in this technique. This study therefore aimed to develop a surgical technique for ligament-balanced implant alignment based on PSI, and to present the results obtained using this technique. Materials and Methods: 25 patients were included in this prospective study. PSI was used for the resection of the extension gap. Ligament tension was measured after removal of all accessible osteophytes. In the event of asymmetry, the distal femur resection was adjusted up to 2.5° using an adjustable cutting block. The aim was to achieve a symmetrical extension gap without release, not a neutral leg axis. Femoral rotation was aligned on the basis of ligament tension. Patients were followed up 3 months postoperatively. Results: The postoperative whole-leg axis was 2.8°±1.6° varus. Patients achieved a flexion of 118.9°±9°, a Knee Score of 91.5±3.2 and a Function Score of 86.8±8.3 points. Conclusion: For the first time, the new surgical technique described here permits a functional, ligament-balanced implant alignment based on PSI. It was shown to be safe, with encouraging clinical and radiological results.